Shortening of patellar tendon after total knee arthroplasty (TKA) was previously reported by several studies. Its etiology still remains controversial. Patellar tendon shortening, a direct cause of patella baja, has a dramatic negative impact in terms of clinical outcomes after TKA. Main objective of this study is to assess the feasibility of utilizing a different technique with Ultrasound that is easy to use, cost-effective and able to eliminate the problem of differential magnification occurring in other techniques which count on standard x-rays and to establish the correlation between clinical outcomes and changes in patellar tendon length and thickness after TKA. The study was designed as prospective cohort and, after a minimum of 4-year-follow up period, 47 knees of 24 patients who had undergone primary TKA without patellar resurfacing were included in the study. All patients were scored with Kujala and HSS scores and all patellar tendons were evaluated with USG regarding their length and thickness. We used conventional grey-scale ultrasound imaging (US) to determine any changes in patellar tendon morphology. All cases were evaluated by the same radiologist. The patellar tendon was examined with the knee in 30° flexion. The flexion angle helped to stretch the extensor mechanism and avoid anisotropy (concavity) of the patellar tendon. The transducer was placed along the long axis of the tendon. The patellar tendon was initially examined in the longitudinal plane in order to measure the total length. Then, total length was divided into three parts and sagittal thickness was calculated at the proximal, median, and distal thirds of the patellar tendon. Both the length and thickness of the tendon were measured before surgery and at the 4th year of follow-up. Of the 47 knees that were included in our study, the mean pre-operative and postoperative length of the patellar tendon was 40.78±6.15 mm and 35.93±4.52 mm. Our results suggested significant shortening of the patellar tendon after primary TKA surgery (p<0.05). Intergroup analysis suggested that reduced sagittal thickness in the proximal third of the tendon was more strongly correlated with an increase in functional outcomes (p<0.05). Our results suggested no significant difference in clinical outcome scores between patients with increased or decreased length of the patellar tendon after TKA (p>0.05). We suggest that determining morphologic changes in sagittal thickness as well as length is important in explaining some of the ambiguous causes of anterior knee pain and impaired clinical outcomes after TKA. More accurate documentation of morphologic changes in the patellar tendon after TKA will certainly help to develop new techniques by surgeons or avoid some existing routines that may harm the tendon. USG is a feasible method for evaluating patellar tendon morphology after TKA but more future studies are needed

An understanding of the remodelling of tendon is crucial for the development of scientific methods of treatment and rehabilitation. This study tested the hypothesis that tendon adapts structurally in response to changes in functional loading. A novel model allowed manipulation of the mechanical environment of the patellar tendon in the presence of normal joint movement via the application of an adjustable external fixator mechanism between the patella and the tibia in sheep, while avoiding exposure of the patellar tendon itself. Stress shielding caused a significant reduction in the structural and material properties of stiffness (79%), ultimate load (69%), energy absorbed (61%), elastic modulus (76%) and ultimate stress (72%) of the tendon compared with controls. Compared with the material properties the structural properties exhibited better recovery after re-stressing with stiffness 97%, ultimate load 92%, energy absorbed 96%, elastic modulus 79% and ultimate stress 80%. The cross-sectional area of the re-stressed tendons was significantly greater than that of stress-shielded tendons. The remodelling phenomena exhibited in this study are consistent with a putative feedback mechanism under strain control. This study provides a basis from which to explore the interactions of tendon remodelling and mechanical environment

Introduction: Patellar tendon is one of the main donor sites for graft. Postoperatively, during the healing procedure there are changes, which we recorded and combined them with the clinical image respectively. Material and Methods: During the period 1998–2001 in Sports Injury Unit, we operated for Anterior Cruciate Ligament insufficiency with autologous Bone Patellar Tendon Bone (BPTB) graft 265 patients. We used autologous BPTB graft from the middle third. We got near the two parts after taking the graft and we sewed very well the peritendon fascia. All patients, with few differentiations, followed the same rehabilitation program. Seventy -seven of them (44 men and 33 women ranging from 17 to 44 years -mean: 24,3 years), were imaged postoperative with MRI at specific intervals from the operation between 3–36 months. In the same time we checked the patients clinically. Results: No one study can answer which is the exact time of satisfying or complete healing. Our study shows elements of scar tissue in the middle third of patellar tendon which is decreasing given time. After the 12th month, the proportion between healthy and scar tissue changes and healthy tissue become dominant. But in some cases scar is still existing even after 36 months. The clinical problems such as anterior knee pain are not existed after the 8th postoperative month. Conclusion: In conclusion, we can say that “regeneration” and healing of patellar tendon occurs mainly during the first postoperative year, but it doesn’t stop after this time. So, we couldn’t recommend this donor site for revision reconstruction before the completion of one year postoperatively

We compared the biological characteristics of extrinsic fibroblasts infiltrating the patellar tendon with those of normal, intrinsic fibroblasts in the normal tendon in vitro. Infiltrative fibroblasts were isolated from the patellar tendons of rabbits six weeks after an in situ freeze-thaw treatment which killed the intrinsic fibroblasts. These intrinsic cells were also isolated from the patellar tendons of rabbits which had not been so treated. Proliferation and invasive migration into the patellar tendon was significantly slower for infiltrative fibroblasts than for normal tendon fibroblasts. Flow-cytometric analysis indicated that expression of α5β1 integrin at the cell surface was significantly lower in infiltrative fibroblasts than in normal tendon fibroblasts. The findings suggest that cellular proliferation and invasive migration of fibroblasts into the patellar tendon after necrosis are inferior to those of the normal fibroblasts. The inferior intrinsic properties of infiltrative fibroblasts may contribute to a slow remodelling process in the grafted tendon after ligament reconstruction

Introduction: Anterior cruciate ligament (ACL) rupture impairs knee stability. Reconstruction of the ACL is therefore performed to restore knee stability and avert risk of subsequent ligament and meniscal injury. Bone-patellar tendon-bone autograft is the most commonly employed technique for ACL reconstruction and considered the “gold standard”. Although 10% postoperative patellar tendon shortening has been reported with this technique, there are no systematic studies assessing the effect of this shortening on patellofemoral joint (PFJ) biomechanics under loading conditions simulating normal physiologic activity. The purpose of this study was to determine if 10% shortening of the patellar tendon affected PFJ biomechanics. Methods: Patellofemoral contact characteristics were evaluated in cadaveric knees before and after patellar tendon shortening. Tendon shortening was performed using a specifically designed device that shortened the tendon without interfering with its anatomic and physiologic integrity. Conditions simulating light physical activity such as level walking were recreated by applying physiological quadriceps loads and corresponding angles of tibial rotation to the PFJ at 15°, 30° and 60° of knee flexion. PFJ contact areas were measured at each position of knee flexion before and after patellar tendon shortening using the silicone oil-carbon black powder suspension squeeze technique (3S technique, . Yao & Seedhom, . Proc Instn Mech Engrs. 1991. ;. 205. :. 69. –72. ). Differences were compared using the Wilcoxon signed rank t-test, with p< 0.05 required for statistical significance. Results: Twelve unembalmed cadaveric knees (median age 81.8 years, 8 female: 4 male) were available for study. Five knees had evidence of osteoarthritic changes, and were rejected. The remaining 7 knees were macroscopically intact and were considered adequate for the experimental procedure. The mean patellofemoral contact areas and stresses determined preoperatively were comparable to those reported in normal knees in previous studies. Following patellar tendon shortening, PFJ contact areas were displaced superiorly on the patellar articular surface and distally on the femoral articular surface. Although the PFJ contact area increased by 17% at 15° of knee flexion (p=0.04), no significant change occurred at 30° or 60° of knee flexion (p> 0.05). Patellofemoral contact stress did not differ before and after patellar tendon shortening (p> 0.05) at any angle of knee flexion. Conclusions: Our results suggest that with light activity such as level walking, a 10% postoperative shortening of the patellar tendon does not alter patellar tracking (in particular contact stresses) and therefore may not impact biomechanics of the patellofemoral joint. Extrapolating these results to the clinical scenario, deleterious consequences on the patellofemoral joint are unlikely after bone-patellar tendon-bone autograft reconstruction of the ACL despite the possibility of postoperative patellar tendon shortening

Introduction: Patients with neglected patellar tendon ruptures present with weakness, instability, extensor lag and sometimes pain. Reports in the literature describe autograft and allograft reconstruction and sometimes quadricepsplasty. Post-operative splintage with a cast or brace is often recommended. Aim: To describe a simple effective method of surgical treatment for neglected ruptures of the patellar tendon. Method: Patients who were included all had neglected patellar tendon ruptures that were initially misdiagnosed or had failed other treatment. Through a midline incision scar tissue was excised and two or three strong cerclage wires were used to approximate the patella and ruptured tendon. The wires were passed from the quadriceps tendon to the absorbable sutures in the tibia. No quadricepsplasty was necessary. Following the surgery immediate mobilisation was initiated without the use of a brace. The wires were removed six months following surgery. Results: Four patients were treated at an average of 29 months following the initial injury. The average follow- up was 26 months (range: 13 to 42 months). The average range of motion was 110 degrees. All patients had improved quadriceps strength, no extensor lag and had returned to work. Conclusion: We have described a simple effective method of treatment without the use of autograft or allograft. The strong cerclage wires allowed immediate mobilisation

Purpose of study. To study the effect of different shoes and orthotics have on patellar tendon tensile forces. Patellar tendinopathy is an overuse injury that affects tennis players and in high impact sports like basketball, volleyball and running has an incidence of 20%. The tensile forces in the patellar tendon can be reliably measured with an intratendinously placed fibre optic tube and wireless transmission device allows for dynamic testing. The biggest strain differentials have been confirmed in jumps from 30cm height. Tennis is played on 3 major different court surfaces and there is a variety of commercially designed tennis shoes on the market. Materials and methods. 6 male tennis players, ages 18–49 were enrolled for this study. A fibre optic cannula was placed in the middle of the proximal pole of patella tendon from lateral to medial direction in the dominant knee. The patellar tendon tensile forces deform the fibre optic cannula in turn modulating the light signal passing through the optic cannula. The drag in the fibre optic sensor signal was used to measure the tensile forces in the patellar tendon. MLTS 700 goniometer were utilized to measure and record the amount of flexion with each jump to standardize results for different shoes and orthotics. Results. The results of patellar tendon tensile forces measurements for different players, different shoes and orthotics showed no trend or statistical difference for any particular shoe or orthotic. Conclusions. Fibre optic measurements of the effect of different shoes on patellar tendon tensile forces did not show a distinct advantage for any shoe above another. 1 DISCLOSURE

In order to clarify the role of cytokines in the remodelling of the grafted tendon for ligament reconstruction we compared the responses to interleukin (IL)-1β, platelet-derived growth factor (PDGF)-BB and transforming growth factor (TGF)-β1 of extrinsic fibroblasts infiltrating the frozen-thawed patellar tendon in rats with that of the normal tendon fibroblasts, in regard to the gene expression of matrix metalloproteinase (MMP)-13, using Northern blot analysis. We also examined, immunohistologically, the local expression of IL-1β, PDGF-BB, and TGF-β1 in fibroblasts infiltrating the frozen-thawed patellar tendon. Northern blot analysis showed that fibroblasts derived from the patellar tendon six weeks after the freeze-thaw procedure in situ showed less response to IL-1β than normal tendon fibroblasts with respect to MMP-13 mRNA gene expression. The immunohistological findings revealed that IL-1β was over-expressed in extrinsic fibroblasts which infiltrated the patellar tendon two and six weeks after the freeze-thaw procedure in situ, but neither PDGF-BB nor TGF-β1 was over-expressed in these extrinsic fibroblasts. Our findings indicated that IL-1β had a close relationship to matrix remodelling of the grafted tendon for ligament reconstruction, in addition to the commencement of inflammation during the tissue-healing process

We performed a biomechanical and histological study to clarify the effect of stress enhancement on the in situ frozen-thawed patellar tendon of the rabbit as a tendon autograft model. We used 48 Japanese White rabbits divided into three groups. In group 1, the patellar tendon underwent in situ freeze-thaw treatment with liquid nitrogen to kill intrinsic fibroblasts. In group 2, after similar treatment, the medial and lateral portions were resected so that the cross-sectional area was reduced by a third. In group 3, after treatment, the cross-sectional area was reduced by a half. In groups 2 and 3, the stress in the tendon was calculated theoretically to be 150% and 200% of the physiological stress during locomotion. Eight rabbits in each group were killed at three and six weeks, respectively. At three weeks, the mean values for the tensile strength of groups 2 and 3 were 113.7% and 75.7% of that of group 1, and at six weeks 101.2% and 57.4%, respectively. The tensile strength in group 3 was significantly lower than that in groups 1 and 2. The histological findings in group 2 were similar to those in group 1, although an acellular area appeared to be wider in the core portion compared with group 1 at each period. In group 3, the collagen bundles of the tendon were less organised than those of groups 1 and 2. Our findings showed that stress enhancement affects the remodelling of the frozen-thawed patellar tendon and that excessively high stress reduces the mechanical properties of the tendon. This indicates that high stress on the patellar tendon autograft should be avoided during ligament reconstruction

Obesity decreases patellar tendon stiffness in females but not males Introduction Patellar tendon (PT) injuries are frequent due to excessive mechanical loading during strenuous physical activity. PT injury incidence is higher in females and obese individuals. The reason behind higher tendon injury incidence in females and obese individuals might be structural changes in tendons such as stiffness or elasticity. Tendon stiffness can recently be quantified using shear wave elastography (SWE). We aimed to examine the stiffness of PT in healthy sedentary participants using this new technology. This prospective study was carried out with 58 (34 female, 24 male) healthy sedentary participants between the ages of 18–44 years (27.5±7.7 years). Body mass and body fat percentage were measured with the Bioelectrical Impedance method using Tanita BC-418 MA Segmental Body Composition Analyser (Tanita Corporation, Tokyo, Japan). Participants were subsequently categorized into ‘normal-weight’ (BMI < 23 kg/m2) and ‘obese’ (BMI>27.5 kg/m2). SWE of the PT was measured with the ACUSON S3000 (Siemens Medical Solution, Mountain Wiew, CA, USA) ultrasound device using the Siemens 9L4 (4–9 MHz) linear-array probe with the Virtual Touch Imaging Quantification® method. The measurement was performed by placing the US probe longitudinally on patellar tendon with knee flexed at 30°. The region between about 1 cm distal of patellar bone-tendon junction and 1 cm proximal of bone-tendon junction of tibia was used for PT stiffness measurement (Figure 1). Average of three successive measurements at 10 sec intervals was recorded as PT stiffness. PT stiffness was quantified with MATLAB Version 2015 (Mathworks, Massachusetts, USA) by converting colour data into numbers. PT stiffness, in males, in females, in normal males, in obese males, in normal females, and in obese females was 8.6±1.0 m/sec, 7.4±1.1 m/sec, 8.6±1.1 m/sec, 8.5±1.0 m/sec, 7.9±0.9 m/sec, and 6.2±0.9 m/sec, respectively. Average body fat percentage in males, in females, in normal males, in obese males, in normal females, and in obese females was 20.1±7.4 kg/m2, 30.1±8.1 kg/m2, 15.4±5.2 kg/m2, 24.7±4.6 kg/m2, 25.6±5.5 kg/m2, and 38.1±5.0 kg/m2, respectively. Males PT stiffness was higher when compared to that of females (p=0.000). PT stiffness was similar in obese and normal males (p=0.962) but obese females had lower PT stiffness compared to normal females (p=0.001). PT stiffness of females was lower than males and obesity decreased PT stiffness in females but not in males. The possible explanation of lower PT stiffness in females might be due to their higher estrogen levels that lead to a decrease in estradiol level and collagen synthesis. Lower tendon stiffness in obese females might be metabolic effects due to the increased adipose tissue that contains proteins such as adipokinome, chemerin, lipocalin 2, serum amyloid A3 and adiponectin. These proteins lead to disturbance of tendon homeostasis and decreased collagen content. Altered tendon homeostasis and decreased collagen content may lead to a decrease in tendon stiffness. Decreased PT stiffness in especially in obese women might be associated with increased risk of PT injury

Abstract. Objectives. The need for gender specific knee arthroplasty is debated. This research aimed to establish whether gender differences in patellar tendon moment arm (PTMA), a composite measure that characterises function of both the patellofemoral and tibiofemoral joints, are a consequence of knee size or other variation. Methods. PTMA about the instantaneous helical axis was calculated from positional data acquired using optical tracking. First, data post-processing was optimised, comparing four smoothing techniques (raw, Butterworth filtered, generalised cross-validation cubic spline interpolated and combined filtered/interpolated) using a fabricated knee. Then PTMA was measured during open-chain extension for N=24 (11 female) fresh-frozen cadaveric knees, with physiologically based loading and extension rates (420°/s) applied. Gender differences in PTMA were assessed before and after accounting for knee size with epicondylar width. Results. Combined smoothing enabled sub-mm accuracy (root-mean-squared (RMS) error 0.16mm, max error 0.47mm), whereas large errors were measured for raw (RMS 3.61mm, max 23.71mm), filtered-only (RMS 1.19mm, max 7.38mm) and interpolated-only (RMS 0.68mm, max 1.80mm) techniques. Before scaling, average PTMA throughout knee flexion was 46mm and mean, maximum, and minimum absolute values of PTMA were larger in males (mean differences >8mm, p<0.001), as were the PTMAs at terminal extension and flexion, and the change in PTMA from peak to terminal extension (differences >4mm, p<0.05). After scaling, the PTMA in deep flexion and the change in PTMA from peak to terminal extension were still larger in male knees (differences >2mm, p<0.05). The flexion angle of peak PTMA, unaffected by scaling, was closer to terminal extension for female knee (female 15°, male 29°, p<0.05). Conclusion. Gender differences in PTMA were identified both before and after accounting for knee size, with implications for gender-specific arthroplasty and musculoskeletal models. The developed measurement framework could also be applied in vivo for accurate measurement of the PTMA. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Two men, aged 21 and 50 years, were seen with ossification of the patellar tendon after injury to the knee in adolescence. They complained of pain and had patella alta. Large bony masses were excised from below the affected patellae. The patellar tendon was then reconstructed using a Leeds-Keio ligament. The results at six and ten years, respectively, were good, with neither patient having pain or an extension lag

Tendons and ligaments are similar in composition but differ in function. Simple anatomical definitions do not reflect the fact individual tendons and ligaments have unique properties due to their adaptation to a specific role. The patellar tendon is a structure of particular clinical interest. A null hypothesis was declared stating that the patellar tendon is not significantly different in terms of matrix composition and collagen fibril diameter to other tendons. The lateral and medial collateral ligaments (LCL, MCL), anterior and posterior cruciate ligaments (ACL, PCL), together with the long digital extensor, superfi-cial digital extensor and patellar tendons (LDET, SDFT, PT) were harvested from 3 cadaveric ovine hindlimbs. The extracellular matrix was assessed in terms of water, collagen and total sulphated glycosaminoglycan (GAG) content. The organisation of the collagen component was determined by an ultrastructural analysis of collagen fibril diameter distributions using electron microscopy, together with values for the collagen fibril index (CFI) and mass-average diameter (MAD). There were significant differences between ligaments and tendons. The PT had a bimodal collagen fibril diameter distribution with CFI72.9%, MAD 202nm, water content 53.1%, GAG content 2.3 g/mg and collagen content 73.7%, which was not significantly different from the other tendons. The results of this study support the null hypothesis suggesting that the patellar tendon is similar to other tendons and demonstrate that tendons have different characteristics to ligaments

We studied changes in patellar tendon length after reconstruction of the anterior cruciate ligament using either the medial third of the patellar tendon as a graft (n = 40) or a Leeds-Keio artificial ligament (n = 40). Both types of ligament replacement had been supplemented with a MacIntosh extra-articular lateral substitution. The mean change in length in the tendon graft group was 6% (SD 5.39); in the Leeds-Keio group it was 2.4% (SD 4.93). The change in length was significant in both groups, but shortening was more frequent and more severe in the tendon graft group. There was shortening of 10% or more in 25% of knees after patellar tendon graft and 7.5% after use of a Leeds-Keio prosthesis

We describe a new method for reconstructing the patellar tendon following combined injury to the patellar tendon and anterior cruciate ligament (ACL). Combined injuries to the patellar tendon and the ACL represent a rare and potentially serious injury pattern. The injury to the patellar tendon can often go undiagnosed at primary presentation. Reconstructive options for the patellar tendon are described but can be technically difficult, particularly if ipsilateral hamstring has been used for anterior cruciate ligament reconstruction. Evidence suggests combined injuries generally lead to poor long term outcome. We describe a case of a 26 year old male who presented with a reconstructed ACL and a patellar tendon deficient knee. Diagnosis was confirmed on Magnetic Resonance Imaging (MRI). Ipsilateral hamstrings had been used as donor for ACL reconstruction. An Achilles tendon allograft with distal bone block was used in combination with contralateral semitendinosus and gracilis autograft to reconstruct the three bundles of the patellar tendon. The patient experienced no postoperative complications and was followed up radiologically and clinically. Computer Topography imaging performed at 6 months post-operatively showed union of the bony Achilles tendon block. MRI performed 1 year post-operatively showed good incorporation of the tendinous grafts and no evidence of degeneration or tearing. Oxford knee score at 6 months post-operatively was 31/48. One year post-operatively full pre-injury activity level had been achieved. We believe this method to provide adequate strength and integrity, enabling early rehabilitation following this rare injury. It has also been shown to give a good functional outcome

Patella infera can cause knee pain and lead to patellofemoral osteoarthritis. Treatment is usually unsatisfactory. We describe a case of severe patella infera after operative treatment for fracture of the patella. We used Ilizarov external fixation and gradual lengthening of the patellar tendon. The patellar height was restored and the patient’s symptoms were much improved

Aims: To evaluate the morphologic changes in the patellar tendon 10 years after harvesting its central third for reconstruction of the anterior cruciate ligament, and examine the association between the morphologic changes and the occurrence of anterior knee pain of the patients. Methods: Thirty-one patients who had undergone an anterior cruciate ligament reconstruction using central-third bone-patellar tendon-bone autograft with a closure of the patellar tendon defect were included in this study. An ultrasonographic and Power Doppler examination was performed at a mean follow-up of 10 years. Results: Ultrasonography of the harvested patellar tendon showed intratendinous calcification in 9 patients, hypoechoic lesion in 20 patients, hyperechoic lesion in one patient, and peritendinous changes in one patient. No abnormality was visible in the contralateral (normal) patellar tendons of the 31 patients. The harvested patellar tendon was significantly thicker than the contralateral patellar tendon both at the proximal third (p=0.017) and at the distal third (p=0.020) of the tendon. Patellar osteophytes were more common in patients with anterior knee pain than without it (p=0.05). Conclusions: Sonographic morphologic changes of the patellar tendon were common 10 years after the harvesting procedure. Also, the harvested patellar tendon was significantly thicker than the normal patellar tendon

Introduction: Patello-femoral instability (PFI) and pain may be caused by anatomical abnormality. Many radiographic measurements have been used to describe the shape and position of the patella and femoral trochlea. Some are difficult to apply when dysplasia is present. This paper describes a simple new MRI measurement of the axial patellar tendon angle (APTA), and compares this angle in patients with and without patello-femoral instability. Method: Axial MRI images of the knee of 20 patients with PFI and 20 normal knees (isolated acute ACL rupture) were used for measurement. The angle between the patellar tendon and the posterior femoral condylar line was assessed at three levels from the proximal tendon to its insertion. Results: In normal knees, the APTA is 11 degrees of lateral tilt at all levels from the proximal tendon to its distal insertion. In PFI knees, the APTA is 32 degrees at the proximal tendon, 27 degrees at the joint line and 22 degrees at the distal insertion. The difference is significant (p< 0.001) at all levels. Discussion: Measurement of the APTA is reproducible and is easier than many other indices of patello-femoral anatomy. In PFI, the APTA is increased by 21 degrees at the proximal tendon and by 11 degrees at its distal insertion. In PFI, the patella is commonly tilted laterally. This is matched by the orientation of the patellar tendon. The increased tilt of the tendon is only partially corrected at its distal insertion with an abnormal angle of tibial attachment. When performing distal realignment procedures, angular correction as well as displacement may be appropriate

Objective: The aim of this study was to compare different patellar tendon repair constructs. Materials and Methods: Eight pairs of cadaveric legs were used to compare metal suture anchor repair with “standard” Krakow tendon suture through patella bone tunnels and steel box wire augmentation loop repair. Each leg was retested with box wire augmentation loop and simple 2/0 polyglactin suture repair. The repairs were tested by mounting the legs on a specially designed rig on a materials testing machine which allowed the leg to be cycled from 90° knee flexion to full extension. The specimens were cycled 1000 times at 0.25Hz or until the repair failed. Optical markers were attached to the leg which enabled the repair gap and knee angle to be monitored during testing (Smart Capture and Analyser Tracking system, Padua, Italy). Results: Six out of eight suture anchor repairs failed, all suture bone tunnel repairs with augmentation loops completed 1000 cycles. One out of 16 augmentation loop with simple 2/0 suture repair failed. For all specimens regardless of repair type that completed 1000 cycles there was no significant difference in repair gap distance. Conclusion: Suture anchors alone do not provide a strong enough construct for patellar tendon repair. The box wire augmentation loop is key to maintaining patellar tendon repair. Krakow tendon sutures secured through patellar bone tunnels do not provide additional benefit to a simple appositional suture and box wire augmentation loop

Patella infera may occur after reconstruction of the anterior cruciate ligament (ACL), high tibial osteotomy and total knee replacement (TKR). Restriction of movement of the knee and pain may result. Our aim was to compare the incidence and to assess the effects of patella infera after TKR and unicompartmental knee replacement (UKR). We reviewed radiographs of the knees of 84 patients who had had either TKR or UKR as part of a randomised, controlled trial. The length of the patellar tendon was measured on serial radiographs taken before, at eight months and at five years after operation. There was no significant change in the length of the patellar tendon after UKR, but a significant reduction was observed after TKR. Five years after the operation, the shortening of the tendon had increased to a mean of 3.5 mm. Of the knees with TKR reviewed at five years, 34% developed patella infera, defined as 10% or more of shortening, compared with 5% of those with UKR. Shortening was greatest in those knees which had required a lateral release; in this subgroup the mean shortening was 7.2 mm. Shortening correlated with restriction of movement and pain in the knee. Our study has shown that patella infera develops in most patients after TKR with lateral release, and in approximately 25% of patients after TKR without this additional procedure. Patella infera rarely occurs after UKR. It is associated with restriction of movement and pain in the knee. It may be an effect of the more extensive exposure required to perform TKR and may, in part, explain the better clinical results of UKR

Purpose of the study: The issue of which graft to choose for anterior cruciate ligament (ACL) reconstruction is still a matter of debate. An analysis of the literature reveals the difficulty encountered when performing comparative trials. It is also difficult to demonstrate significant differences with results obtained with an insufficient number of patients. We propose here a meta-analysis in order to combine the results obtained with different comparative studies. Material and methods: The literature search (Medline 1990–2005) was based on the following selection criteria: ACL reconstruction, patellar tendon (PT), gracilis and semitendinous (four-strand hamstring) reconstruction and comparative prospective study. Studies were retained with: > 30 patients per group, minimum follow-up 24 months, IKDC score. Evaluation criteria retained were: anterior pain, resumed activity, IKDC score, differential laxity. The relative risk (RR) statistical method with 95% confidence interval (CI) was applied. Means were calculated and the chi-square and z-tests were applied. Results: Thirteen studies satisfied our inclusion criteria. These studies had included more than 1300 transplants. Mean rate of anterior pain was 23.2% with PR and 17.3% with hamstring reconstructions. The RR was 0.73 with a CI different from 1. The difference was significant. Resumption of sports activities at the same level, subjective assessment, number of failures, and overall IKDC score were not statistically different between the two types of transplants. The IKDC laxity score was not different but the residual maximal manual differential laxity was greater in the hamstring patients than in the patellar patients in 80% of the cases. Conclusion: At the observed follow-up, free grafting with a four-strand hamstring tendon or a patellar tendon is an effective method for reconstruction of the ACL. Anterior pain is more frequent with the patellar tendon method and residual laxity is greater with the hamstring method. The long-term outcome will determine whether the residual laxity observed with the hamstring graft has a deleterious effect on the meniscocartilaginous structures. This criteria would minimize the advantage of this technique over the patellar tendon technique concerning the initial anterior pain

INTRODUCTION. Patellar tendon (PT) autograft is an excellent choice repairing anterior cruciate ligament (ACL) ruptures. Published studies testing the biomechanical characteristics after plasty usually refer to grafts with 10mm wide. The thickness of PT and geometry of the patella have been overlooked. The purpose of this study was to understand the geometry of PT and patella in our population, regarding their use in Bone - Patellar Tendon - Bone (BTB) technique, in order to evaluate their biomechanical efficiency and study their relationship with anthropometric parameters. MATERIAL. 100 individuals (50/50) who underwent knee MRI (3-Tesla). Ages between 18–65years. METHODS. Retrospective study. Standardized protocol for measuring the PT and patella based in MRI images. Interview to obtain personal data. Statistical analysis using SPSS®. RESULTS. Sample (mean ±SD): age 41 ±14years, weight 73 ±12kg, height 167 ±10cm, BMI 26,04 ±4,13; length PT/patella −41,3 ±6,1mm/29,6 ±4,2 mm, width PT/patella −25,3 ±3,2mm/43,4 ±4,14mm; thickness PT −3,79 ±1,01mm/22,8 ±2,2mm; Men have thicker and wider patella and PT than women (p<0.001). The patella is also longer in males (p<0.001). There is statistical significant relationship between weight and height to width, thickness and length of PT and patella (p<0.01). Body Mass Index (BMI) doesn't have statistical correlation with geometry of the PT and patella. DISCUSSION. The PT remains as an excellent option in ACL repair. The anatomy and quality of the graft are essential to achieving good functional results. The choice of middle third tendon to the BTB plasty does not always correspond to the 10mm width, as used in most biomechanical tests. Also patellar integrity can be at risk (when collecting the bone block) if patella geometry is not considered. To our knowledge, there is only one similar study in literature, preformed in Asian individuals. CONCLUSION. Preoperatively accessing the geometry of Patella and PT can be crucial in obtaining efficient grafts and decreasing morbidity over the extensor mechanism

As treatments of knee osteoarthrosis are continually refined, increasingly sophisticated methods of evaluating their biomechanical function are required. Whilst TKA shows good preoperative pain relief and survivorship, functional outcomes are sub-optimal, and research focus has shifted towards their improvement. Restoration of physiological function is a common design goal that relies on clear, detailed descriptions of native biomechanics. Historical simplifications of true biomechanisms, for example sagittal plane approximation of knee kinematics, are becoming progressively less suitable for evaluation of new technologies. The patellar tendon moment arm (PTMA) is an example of such a metric of knee function that usefully informs design of knee arthroplasty but is not fully understood, in part due to limitations in its measurement. This research optimized PTMA measurement and identified the influence of knee size and sex on its variation. The PTMA about the instantaneous helical axis was calculated from optical tracked positional data. A fabricated knee model facilitated calculation optimization, comparing four data smoothing techniques (raw, Butterworth filtering, generalized cross-validated cubic spline-interpolation and combined filtering/interpolation). The PTMA was then measured for 24 fresh-frozen cadaveric knees, under physiologically based loading and extension rates. Sex differences in PTMA were assessed before and after size scaling. Large errors were measured for raw and interpolated-only techniques in the mid-range of extension, whilst both raw and filtered-only methods saw large inaccuracies at terminal extension and flexion. Combined filtering/interpolation enabled sub-mm PTMA calculation accuracy throughout the range of knee flexion, including at terminal extension/flexion (root-mean-squared error 0.2mm, max error 0.5mm) (Figure 1). Before scaling, mean PTMA throughout flexion was 46mm; mean, peak, and minimum PTMA values were larger in males, as was the PTMA at terminal flexion, the change in PTMA from terminal flexion to peak, and the change from peak to terminal extension (mean differences ranging from 5 to 10mm, p<0.05). Knee size was highly correlated with PTMA magnitude (r>0.8, p<0.001) (Figure 2). Scaling eliminated sex differences in PTMA magnitude, but peak PTMA occurred closer to terminal extension in females (female 15°, male 29°, p=0.01) (Figure 3). Improved measurement of the PTMA reveals previously undocumented characteristics that may help to improve the functional outcomes of knee arthroplasty. Knee size accounted for two-thirds of the variation in PTMA magnitude, but not the flexion angle at which peak PTMA occurred, which has implications for morphotype-specific arthroplasty and musculoskeletal models. The developed calculation framework is applicable both in vivo and vitro for accurate PTMA measurement and might be used to evaluate the relative performance of emerging technologies. For any figures or tables, please contact the authors directly

Introduction: Patello-femoral instability (PFI) and pain may be caused by anatomical abnormality. Many radiographic measurements have been used to describe the shape and position of the patella and femoral trochlea. This paper describes a simple new MRI measurement of the axial patellar tendon angle (APTA), and compares this angle in patients with and without patello-femoral instability. Method: Axial MRI images of the knee of 20 patients with PFI and 20 normal knees (isolated acute ACL rupture) were used for measurement. The angle between the patellar tendon and the posterior femoral condylar line was assessed at three levels from the proximal tendon to its insertion. Results: In normal knees, the APTA is 11 degrees of lateral tilt at all levels from the proximal tendon to its distal insertion. In PFI knees, the APTA is 33 degrees at the proximal tendon, 28 degrees at the joint line and 22 degrees at the distal insertion. The difference is significant (p< 0.001) at all levels. Discussion: Measurement of the APTA is reproducible and is easier than many other indices of patello-femoral anatomy. In PFI, the APTA is increased by 21 degrees at the proximal tendon and by 11 degrees at its distal insertion. In PFI, the patella is commonly tilted laterally. This is matched by the orientation of the patellar tendon. The increased tilt of the tendon is only partially normalized at its distal insertion with an abnormal angle of tibial attachment. When performing distal realignment procedures, angular correction as well as displacement may be appropriate

Patello-femoral instability (PFI) and pain may be caused by anatomical abnormality. Many radiographic measurements have been used to describe the shape and position of the patella and femoral trochlea. This paper describes a simple new MRI measurement of the axial patellar tendon angle (APTA), and compares this angle in patients with and without patello-femoral instability. Method: Axial MRI images of the knee of 20 patients with PFI and 20 normal knees (isolated acute ACL rupture) were used for measurement. The angle between the patellar tendon and the posterior femoral condylar line was assessed at three levels from the proximal tendon to its insertion. Results: In normal knees, the APTA is 11 degrees of lateral tilt at all levels from the proximal tendon to its distal insertion. In PFI knees, the APTA is 33 degrees at the proximal tendon, 28 degrees at the joint line and 22 degrees at the distal insertion. The difference is significant (p< 0.001) at all levels. Discussion: Measurement of the APTA is reproducible and is easier than many other indices of patello-femoral anatomy. In PFI, the APTA is increased by 21 degrees at the proximal tendon and by 11 degrees at its distal insertion. In PFI, the patella is commonly tilted laterally. This is matched by the orientation of the patellar tendon. The increased tilt of the tendon is only partially normalized at its distal insertion with an abnormal angle of tibial attachment. When performing distal realignment procedures, angular correction as well as displacement may be appropriate

Introduction and Aims: We present the preliminary results of patellar tendon shortening (PTS), for severe crouch gait in children with spastic cerebral palsy who were household ambulators. Method: We performed bilateral patellar tendon shortening in 15 patients with severe spastic diplegia between May 1996 and January 2002. The majority had acquired crouch gait because of isolated lengthening of the Achilles tendons in childhood and presented with anterior knee pain and rapidly deteriorating gait and function. The PTS procedure included dividing the patellar tendon in its mid portion, and performing an overlapping repair by suturing the distal tendon to the distal pole of the patella and the proximal segment to the tibial tubercle. The corrected position of the patella was maintained by a K-wire passed transversely through the patella and incorporated into a cylinder plaster, with the knee in extension, for a period of six weeks. Correction of knee flexion deformity was achieved by transfer of semitendonosis to the distal femur or extension osteotomy of the distal femur. Results: Rehabilitation was predictably slow but all patients regained their pre-operative mobility status within one year and the majority surpassed their pre-operative functional level by two years after surgery. There were no tendon ruptures or growth disturbance in the proximal tibia. Average age at the time of surgery was 14.2 years (10–19 years). Mean follow-up was 27 months (12–48 months). Pre- and post-operative Insall index in 17 knees was 0.68cm (0.46 to 1.07cm, SD=0.16cm) and 0.85cm (0.56 to 1.08cm, SD=0.20) respectively (p< 0.001 Students-t test). Pre-operatively, only three sides had a normal index, but post-operatively 14 sides had a normal index. Crouch gait improved in all patients who were reclassified as community ambulators. Thirteen patients still needed crutches. One patient continued to complain of bilateral knee pain 12 months after surgery, had insufficient correction according to the Insall index (0.58cm on the left 0.56cm on the right). Conclusion: Severe crouch gait after appropriate surgical and orthotic management, maybe due to patella alta, quadriceps and ankle plantarflexors insufficiency. We present preliminary results of a salvage procedure, patellar tendon shortening, which seems a reasonable option to treat complex crouch gait in selected patients with cerebral palsy

It appears that double bundle anterior cruciate ligament reconstruction can reproduce the original anatomy of the ligament, restoring normal kinematics and rotational control of the tibia. But an anatomical single bundle reconstruction may present very similar results, with minor technical difficulties and lower costs. We compared two groups of 25 patients each, that underwent ACL reconstruction by the same surgeon, with a follow-up of 12–36 months. One group had double bundle reconstruction with hamstring and the other had single bundle anatomical reconstruction with patellar tendon. Patients underwent a subjective evaluation and clinical testing with instrumented laxity with Rolimeter, and the data entered in the IKDC 2000 scale Double tunnel hamstring Vs bone-tendon-bone: Functional outcome of 85.6% Global Class A and B vs. 82.1% Class A and B. The subjective outcome (IKDC 2000) was 90.93 vs. 91.47. Pivot-shift test with 87% patients in class A and class B at 9.7% Vs 75% patients in class A, 21.4% for class B. The Rolimeter gave an average Lachman value of 2,56 and anterior drawer test of 2,88 Vs average Lachman value of 3.59 and anterior drawer test of 2.92. One leg hop test showed 85.7% knees class A, 9.5% knees class B vs. 90.4% knees class A and, 2.8% knees class B. The subjective score was slightly higher in the single bundle anatomical reconstruction with patellar tendon, despite the overall functional outcome being higher in the double tunnel technique with hamstrings. The average Lachmann in the patellar tendon group was 1 mm higher. The rotational stability in the double tunnel was higher. The same surgeon had better results in the double tunnel hamstrings technique, despite less experienced with this technique, which is more demanding, probably reflecting objective advantages over the single bundle reconstruction with patellar tendon

Purpose: This study sought to compare clinical outcomes and return to activity in high-demand patients following ACL reconstruction with either autograft or allograft patellar tendon using a matched-pairs case-control experimental design. Method: Nineteen matched pairs were obtained based on gender (36.8 % female), age (27.9±8.1yrs autograft versus 28.1±9.1 allograft), and length of follow-up (9.1±2.7yrs autograft versus 10.3±2.6 allograft). All patients reported participating in very strenuous (soccer, basketball etc.) or strenuous (skiing, tennis etc.) sporting activity 4–7 times/ week prior to their knee injury. Patient-reported outcomes included the IKDC Subjective Knee Form, Activities of Daily Living (ADLS) and Sports Activity Scales (SAS) of the Knee Outcome Survey and SF-36. Range of motion, laxity, and functional strength were also assessed. Results: There were no significant differences in patient-reported or clinical outcome measures. Sixteen (84.2%) subjects undergoing autograft reconstruction and 12 (63.2%) subjects reconstructed with allograft were able to participate in strenuous or very strenuous sporting activity at follow-up (p=.34). Similar percentages of subjects were able to return to their pre-injury level of sports activity [12 (63.2%) autograft vs. 11 (57.9%) allograft; p=1.0]. Fewer subjects undergoing reconstruction with autograft reported instability with very strenuous activity [5 (26.3%) autograft vs. 12 (63.2%) allograft], but this difference was not significant (p=.07). Conclusion: While autograft and allograft patellar tendon ACL reconstruction exhibit similar clinical outcomes in high-demand individuals, autogenous patellar tendon grafts may be indicated to allow patients to return to very strenuous levels of activity

The February 2023 Knee Roundup. 360. looks at: Machine-learning models: are all complications predictable?; Positive cultures can be safely ignored in revision arthroplasty patients that do not meet the 2018 International Consensus Meeting Criteria; Spinal versus general anaesthesia in contemporary primary total knee arthroplasty; Preoperative pain and early arthritis are associated with poor outcomes in total knee arthroplasty; Risk factors for infection and revision surgery following patellar tendon and quadriceps tendon repairs; Supervised versus unsupervised rehabilitation following total knee arthroplasty; Kinematic alignment has similar outcomes to mechanical alignment: a systematic review and meta-analysis; Lifetime risk of revision after knee arthroplasty influenced by age, sex, and indication; Risk factors for knee osteoarthritis after traumatic knee injury

Purpose of the study: For medial osteoarthritis with chronic anterior laxity, we propose an original technique combining subtraction osteotomy and extra-articular ligmentoplasty using the lateral quarter of the patellar tendon. Material and methods: WE report a retrospective review of 29 patients (11 males/18 females) aged 29–51 years treated from May 1996 to October 2002. Time from rupture of the anterior cruciate ligament (ACL) and the operation was 17.5 years (range 13–22 years). These patients had had 52 prior operations (more than one per knee). All presented functional instability, a positive pivot test, and anterior laxity measured at 8 mm on average (range 5–10 mm) on KT1000. Pain in the medial compartment was observed in all patients with osteoarthritis noted grade II in 7, grade III in 18 and grade IV in 4. Radological varus measured 5–15°. Lateral subtraction osteotomy fixed with a plate was performed in combination with a patellar tendon autograft using the lateral quarter of the patellar tendon. Immediate mobilization with complete weight bearing was the rule. Results: A mean 5–year follow-up (range 18 months to 9 years). According to the IKDC subjective score, 26 patients were satisfied or very satisfied and 22 of them had resumed their sports activities. Instability persisted in one patient and pain in two. Varus was corrected in three patients but the medial degradation progressed. Anterior laxity measured with KT1000 was 1–6 mm (mean 2 mm). The pivot test was positive in one knee, negative in 18 and revealed slight displacement in 10. Excluding the radiological aspect, the overall IKDC score was 2A, 21B, 6C, 1D. Conclusion: This combined method is particularly interesting for stabilizing chronic ACL instability causing secondary medial degeneration. It treats two conditions with the same approach with an acceptable rate of satisfaction

Purpose: Patellar tendonitis (i.e. jumper’s knee) commonly affects young adult athletes who use their knee extensor mechanism in a repetitive and/or intense manner, such as in basketball and volleyball. There is a small but significant percentage of patients with persistent symptoms despite at least a six-month course of conservative management. For these patients, we perform knee arthroscopy and open patellar tendon debridement. This study presents the indications, technique, and clinical results of open patellar debridement. Method: We investigated the clinical outcomes of 38 consecutive cases of open patellar tendon debridements (3 were bilateral) in 35 patients without previous open ipsilateral knee surgery over 7 years. Results: Two patients (2 knees) were lost to follow-up (94% follow-up rate). The average age at surgery was 29 (SD 10, range 14–51). There were 21 males and 12 females. At an average follow-up of 43 months (SD 21, range 15–92 months), the Lysholm score showed 27 knees with good or excellent results, 4 fair, and 2 poor. The average post-operative IKDC score was 79 (SD 14, range 41–100). When compared to the pre-operative value, the post-operative Tegner Activity Scores showed no change (average change 0, SD 2, p=0.20), and Visual Analog Pain Scores decreased by an average of 6 points (SD 3, p< 0.001). Twenty-seven patients were completely or mostly satisfied with the surgical outcome, 4 were somewhat satisfied, and 2 were dissatisfied. Twenty-seven patients (82%) said that they would have the surgery performed again for the same problem. Conclusion: Patellar tendon debridement significantly reduces knee pain in patellar tendonitis patients without significantly affecting their activity level; the great majority of patients are satisfied with the results of the procedure

Purpose of the study: to prospectively evaluate if day surgery influences post-operative rehabilitation time in sportsmen. Material and Methods. 122 young sportsmen underwent a reconstruction of the ACL with patellar tendon. They were randomly divided up into two groups. Group A (62 patients, mean age 28 years) Day Surgery and Group B (60 patients, mean age 30 years) staying one or two nights in the clinic. In all the same surgical technique by the same surgeon was performed. Peripheral anaesthesia was used in the majority of them. 15% of the subjects in Group A and 17% of the subjects in Group B chose general anaesthetic. The same rehabilitation protocol was applied to all of the subjects. Results were evaluated with the IKDC form. Furthermore, the time crutches were used, the time needed in order to recover complete ROM and the time lapse from surgery to resuming running and sports activities were evaluated. The results were analysed statistically ( paired Student t test). Mean follow up 75 months. Results. The two groups were classified according to the IKDC form:Group A: 53 A , 6 B , 3 C . Group B: 44 A , 14 B, 2 C. The time crutches were used (mean 10 days in both groups) and the average time needed for the recovery of complete mobility was 88 days in Group A and 105 days in Group B. 8% of Group A and 3% of Group B did not recover flection completely (< 5). Patients in Group A started running after an average time of 92 days, and in Group B after an average time of 110 days. 87% in Group A and 83% in Group B resumed sports activities after 161 and 179 days respectively. No statistical difference was evidenced in any parameter evaluated. 97% in group A declared that they were satisfied with the day surgery. Conclusions and Significance. Day surgery ACL reconstruction does not jeopardize the rehabilitation time of sportsmen

Introduction. Tendon injuries remain challenging, secondary healing and prolonged immobilisation result in suboptimal outcome. Previous study by our group showed that demineralised bone matrix (DBM) can result in faster healing of a tendon enthesis. The aim of this study is to test different ways augmenting tendon with DBM to enhance tendon repair and regeneration. Methods. DBM strips were prepared from tibias of mature ewes. Patella, patellar tendon and tibias were dissected and the distal 1 cm of the patellar tendon was excised. 4 models were designed;. Model-1, DBM strip was used to bridge the gap between the tendon and the tibial tuberosity. The DBM strip was stitched to the tendon using one bone anchor. Model-2, similar to model 1 with the use of 2 anchors. Model-3, similar to model 2, construct was off loaded by continuous thread looped twice through bony tunnels sited in the patella and in the tibial tuberosity. Model-4, similar to model 3 with 3 threads as off loading loop. All models were tested for pullout force and mode of failure. Results. The median failure force for model-1 (N=5) was 250N while for model-2 (N=5) was 290N. In model-3 and model-4 failure of the off loading loop was used as end point, 6 samples were tested in each model. Median failure force of model-3 was 767N and for model-4 was 934N. There was no statistical significance between model-1 and model-2 (p=0.249), however statistical significance was found between other models (p=< 0.006). Discussion. A study published in 1996 proved that cortical DBM can be used as ACL graft with evidence of ligamentisation. DBM provides a biologic scaffold with potential for use as ligament and tendon replacement. Our study shows that a tendon rupture can be augmented with DBM giving intial appropriate mechanical strength suitable for in-vivo use

Aim: To determine the short to mid-term outcome differences between patellar tendon (PT) and hamstring (HS) autograft in anterior cruciate ligament (ACL) reconstructions. Methods: Sixty-five patients undergoing primary ACL reconstruction were randomised to receive either a PT or a quadruple HS autograft. Post operatively patients undertook a standard “accelerated” rehabilitation protocol. Patients were reviewed at four and eight months and then after one, two and three years. Results: Anterior knee pain was significantly more common in the PT group at eight months, and again at two years, but not at other times. Pain on kneeling was significantly greater in the PT group at four months and this difference persisted at three years. There was a significantly greater incidence of effusion in the PT group at eight months. Extension deficits were significantly greater in the PT group at eight months and this continued unchanged at three years. Active flexion deficits were significantly greater in the hamstring group at one and two years but not at three years. KT-1000 side to side differences in anterior knee laxity were significantly greater in the HS group from four months through to three years. There were significantly greater peak quadriceps torque deficits in the PT group at four months and at eight months. Sports activity levels were significantly higher in the PT group at four months but this difference had resolved by eight months. Cincinnati scores were significantly higher in the HS group at one year but not thereafter. There was no difference in IKDC ratings between the two groups. Radiographic femoral tunnel widening was significantly more prevalent and greater in the HS but did not correlate with any clinical differences. Radiographic tunnel widening was present at four months and did not change significantly thereafter. Conclusions: Overall, HS autografts were associated with less morbidity but increased anterior knee laxity and radiographic femoral tunnel widening compared with PT autografts. From a functional point of view, there was no significant difference between the two graft types at three years

Ligamentoplasty resorting to autogenous bone-tendon-bone grafts represents an effective long-lasting remedy to the anterior instability of the knee. If this indication has proved effective regarding the stability, the sampling of a piece of the extensor system often brings about a certain morbidity. Various approaches have been advocated concerning the tendinous site: some leave it open, others suture one of the peripheral thirds of the remaining tendon to the other. These various technical choices are likely to alter the morbidity and the patellar level, together with the tissue nature of the site of sampling. The purpose of this study was to assess the effect of the suture of the site of sampling on the patellar level, after a ligament plastic surgery resorting to a bone-tendon-bone graft. To this end, a group of 40 patients whose tendinous site of sampling had been left open was compared to another group of patients whose peripheral thirds of the remaining patellar tendon had been sutured one to the other. The patellar level was assessed with Caton’s, Black-burne’s and Insall and Salvati’s methods on x-rays first taken before and then 6 months after the operation. To analyse the results, we resorted to the reduced gap method and the Student-Fisher one for the comparison between quantitative and qualitative variables, and to the correlation coefficient method for the comparison between quantitative variables. The post-operative values of Caton’s, Blackburne’s and Insall and Salvati’s indexes were respectively 1.002, 0.844, and 1.188 for patients whose patellar tendon had been left open, and 1.023, 0.882, and 1.184 for patients whose tendinous edges had been sutured up. The discrepancy between those values had no statistical significance. Suturing the site of sampling in a bone-tendon-bone ligament plastic surgery has no effect on the patellar level

We have reviewed 40 patients after replacement of a ruptured anterior cruciate ligament with a free graft of the medial third of the patellar tendon, combining this in 17 of the cases with a MacIntosh extra-articular tenodesis. The average age of the patients at operation was 25.4 years; instability of the knee had been present for 1.5 to 9 years, and the mean follow-up was 2.9 years. The results, assessed on subjective stability, were good in 29 patients, over half being able to return to their original sport, and fair in eight. The technique of operation for free patellar tendon grafting is described in detail and the indications for this and for an additional MacIntosh tenodesis are discussed

At the time of publication sixty-three additional patients have been fitted with the patellar tendon bearing prosthesis. Twenty of these were new amputees, and forty-three were old amputees who had previously worn a conventional limb. Of this group, nine were considered failures. The contra-indications for fitting now include: 1) coincident knee derangement such as cruciate or collateral ligament laxity (the trauma that causes the amputation often produces knee injuries as well; in this event the side irons of the conventional prosthesis help to support the knee); 2) scars in the popliteal fossa, such as those produced by exploration of the popliteal vessels; 3) marked variation in stump size such as in rapidly growing children or obese people; and 4) labourers obliged to work on rough ground, which places additional strain on the knee

Introduction and Aims: Some authors have suggested that, in females, the results of ACL reconstruction using hamstring tendon (HS) grafts are inferior to those using patellar tendon (PT) grafts, while others have suggested that HS grafts may be preferable. This study compared the mid-term results of ACL reconstruction in females using both graft types. Method: Sixty-six females who had undergone primary ACL reconstruction using either HS (n=43) or PT autograft (n=22) were evaluated at a mean 3.7 years follow-up (range 2.6–5.5). All procedures were performed by the same experienced knee surgeon using an arthroscopically assisted, single-incision technique, with Endobutton femoral fixation and interference screw tibial fixation. The same rapid rehabilitation protocol (immediate full extension and weight-bearing; no brace) was used for all patients. Assessment was performed by an independent orthopaedic surgeon and included IKDC 2000, SF-36 and Cincinatti Sports Activity scores and measurements of anterior knee pain (AKP), kneeling pain and anterior knee laxity (KT-1000). Results: The overall results in both groups were good. One PT patient sustained a traumatic graft rupture. The HS patients had higher Cincinnati Sports Activity Scores (HS: 83 vs. PT: 72, p< 0.05), but there was no difference in IKDC subjective scores (HS: 89.6 vs. PT: 85.7). For the SF-36, the HS group scored significantly higher on Physical Functioning (HS: 95.4 vs. PT: 89.8, p< 0.01) and General Health subscales (HS: 87.5 vs. PT: 78.4, p< 0.05), but there were no differences for the other subscales. Although there was no significant difference in AKP between the two groups (HS: 1.3/10 vs. PT: 1.7), there was a significantly greater mean kneeling pain in the PT group (PT: 4.0/10 vs. HS: 1.3, p< 0.001). There was no difference between the groups in side to side difference in anterior knee laxity at 134N (HS: 1.7mm vs. PT: 1.8mm). Seventy percent HS and 71% PT patients had a difference of < 3mm, with all remaining patients having 3–5mm difference. There was no difference in terms of overall IKDC knee examination grade, but the HS group had a lesser (hyper)extension deficit (HS: 1.0° vs. PT: 1.8°, p< 0.05). Conclusion: Both PT and HS ACL reconstructions appear to provide satisfactory results in females, but HS grafts are associated with fewer symptoms, a greater return to pre-injury level of activity and higher quality of life scores

We performed MRI on 16 patients who had had reconstruction of the anterior cruciate ligament (ACL) with a mid-third bone-patellar-tendon-bone autograft. Our aim was to assess the tendon and the site of its insertion at an average of seven years after the original operation. In four of these patients biopsies were taken from the donor site when they had revision of their original operation. MRI showed reconstitution of the tendon into the patellar defect with no evidence of bone formation. Six patients had a persistent defect in the patellar tendon itself. Histological examination of the biopsies of the donor site showed an indirect pattern of insertion with absence of the normal fibrocartilage zone. These morphological changes may adversely affect the biomechanical properties of the healed donor site and we suggest that another graft taken from this site may not be suitable for use in a further operation for reconstruction of the ACL

Purpose: Free patellar tendon plasty is classically used for the treatment of chronic anterior instability of the knee. Good functional results may however be compromised by invalidating anterior pain. The purpose of this randomised trial was to obtain a prospective comparison of outcome after hamstring plasty or patellar tendon plasty. Material and methods: One hundred patients with an isolated tear of the anterior cruciate ligament were included in the study between May 1998 and 2001. Exclusion criteria were history of fracture, grade II laxity, and tear of the contralateral ACL. Patients were assigned to one of the treatment arms in random order in the operating room: Group A: arthroscopic free patellar tendon-bone graft; Group B: arthroscopic free four-strand hamstring graft. Two metal interference screws were used for fixation in all cases. The Aglietti method was used to calculate the position of the bore holes in all cases. The same rehabilitation protocol, in the same centre, was applied in all cases. The two groups were comparable for epidemiological, clinical, radiological, and instrumental laxity (KT1000®) data. IKDC criteria, activity level (sports), and instrumental measurement of laxity (KT1000® Medtronic) were used to assess outcome. Differences were considered significant for p < 0.05. Results: At mean follow-up (24 months, range 6 – 38) groups A and B were not significantly different for delay to resumed sports activity at the initial level, motion, clinical examination of ligaments, IKDC global score, and radiological evolution. At six months, 30% of the patients in group A complained of anterior pain; 20% of the patients still complained of pain at one year. In group B, femoropatellar pain or pain at the harvesting site was reported by 8% of the patients at six months and 4% at one year (p = 0.0005). These differences were no longer present at two years. The instrumental differential laxity was 0.66±1.1 mm in group A and 1±1.5 mm in group B (p =0.20). Two repeated trauma-induced tears were observed in group B. Conclusion: The preliminary results of this prospective randomised trial confirm the low morbidity of the harvesting site for hamstring grafts and the reliable stability of hamstring repair of isolated ACL laxity. A longer follow-up is however needed for long-term validation, particular concerning secondary distension of hamstring grafts as is frequently reported in the literature and which we have also observed in certain patients treated before this series

In the last few years the number of women who practise sport activities has substantially increased and this has led to an increase in the incidence of ACL tear in females. The aim of this study is to assess outcome differences at a minimum 3-year follow-up after ACL reconstruction in women using either a patellar tendon (BPTB) or a quadrupled-looped hamstring (DSTG) autograft fixed with modern devices. Fifty women with a chronic, isolated ACL tear were randomised to receive a DSTG or BPTB graft for ACL reconstruction. Both groups were comparable as to age, injury-surgery, activity level, meniscal tears, surgical technique and reabilitation. All patients were prospectively evaluated by an independent observer using the IKDC form, the FKSAKP Score, the KT-1000 arthrometer and the Cybex NORM dynamometer. A radiographic study was performed to investigate tunnel widening. All but two patients were satisfied with the reconstruction. The average side-to-side difference in anterior tibial translation was 2.4 mm in the BPTB group and 2.5 mm in the DSTG group. The final result was A (normal knee) in 56% and in 60% of the BPTB and the DSTG knees, respectively. A failure (4%) was present in each group. Muscle strength deficits at 60°/s, 120°/s and 180°/s were within 10% for extensors and within 5% for flex-ors in both groups. No statistically significant differences were found in terms of subjective satisfaction, objective evaluation, knee stability and muscle strength recovery. The BPTB group showed a higher incidence of postoperative kneeling discomfort (p< 0.05) and a larger area of decreased skin sensitivity (p< 0.001). The DSTG group showed a higher incidence of femoral tunnel widening (p=0.02). Using strong and stiff fixation devices, ACL reconstruction in women is not influenced by the graft choice

Purpose of the study: The debate continues on the appropriate tendon to use for anterior cruciate ligament (ACL) reconstruction. There are few comparative data on the different types of grafting material. We propose a retrospective analysis of bilateral ACL reconstruction where a patellar tendon (PT) and hamstring tendons were used in the same patient. Material and methods: This was a phase IV trial. From December 1992 through March 2003, ACL reconstructions of both knees were performed in 46 consecutive patients using the PT for one side and hamstring grafts for the other. Follow-up was at least two years for 38 patients. There was no difference between the knees prior to reconstruction. The postoperative protocol was the same for both knees. The Lysholm Knee Score and the IKDC scores as well as KT1000 arthrometry were recorded. Results: There was no difference between the two sides for laxity (KT1000) or resumed sports activity. Postoperative pain, loss of extension, joint stiffness, and anterior pain were greater on the PT reconstruction side. All patients except two preferred the hamstring reconstruction. Conclusion: The results of this study show that the two types of reconstruction are equivalent in terms of objective outcome but that the subjective assessment favors hamstring reconstruction

Purpose: The aim of this study was to document donor site problems one year after anterior cruciate ligament (ACL) reconstruction and to compare the differencies between hamstring and patellar tendon autografts. Materilas and Methods: Sixty-four patients undergoing primary arthroscopically ACL reconstruction were randomized to have a central third bone patellar tendon bone (PT) autograft (30 patients) or a doubled semiten-dinosus/doubled gracilis (HS) autograft (34 patients). The postoperative rehabilitation regimen was identical for both groups. All patients were examined one year postoperatively. Objective parameters evaluated included pre and postoperative IKDC and Lysholm score, side-to-side KT-1000 maximum-manual arthrometer differences. The Shelbourne score was used to evaluate anterior knee symptoms. Loss of sensitivity in the anterior knee region postoperatively as well as scar sensitivity were also recorded. Results: Three patients (10%) in the PT group had anterior knee symptoms while only one (3%) in the HS group. The mean Shelbourne score was 98 for the HS group and 93 for the PT group but this was not statistically significant. However, 8 pateints (23%) had disturbed sensitivity in the anterior knee region in the HS group, but none in the PT group and this was statistically significant (p< 0.005). Scar sensitivity was present in 3 patients (10%) in the PT group and in one (3%) in the HS group. No differencies were found postoperatively between the groups regarding IKDC, Lysholm score and side-to-side KT-1000 measurements. Conclusions: Although,notstatisticallysignificantpatients in the PT group had more anterior knee symptoms and scar sensitivity, one year postoperatively. In contrast, harvesting of hamstring tendons produces significantly more sensory nerve complications in the anterior knee region than harvesting the middle third of patellar tendon. Both grafts seem to improve equally patients’ performance

This investigation of elite male collegiate basketball players aims to determine 1) the change in 3D dynamic functional variables across a single season and 2) correlate cross-season changes in functional variables with changes in clinical and quantitative ultrasound measures. Eleven male college basketball players (mean age 19, range 18–21 years) from a single team underwent baseline patellar tendon shear wave (SW) elastography and dynamic function at the start of the season (Visit1) and at a late-season time point (Visit2). Players reported their VISA-P scores every two weeks across their 24-week season. Each athlete performed a box-ground-box jump five times while 3D lower extremity kinematic and kinetic variables were collected. Functional measures included for landing (LAND) and take-off (TOFF) phases: knee valgus angle, valgus torque, and peak limb force. Knee valgus angular impulse and ground contact time were also measured. Paired t-tests and Pearson correlation coefficients (r) compared Visit1 and Visit2 variables and assessed the strength of linear dependency, respectively. The mean change in VISA-P score was 15.18 (+/-8.55). No functional variables were different across the season. Clinical, quantitative ultrasound and functional variables were moderately correlated with take-off valgus moment, landing force, take-off force and contact time. Other correlations were low (< 0.4). Our analyses have shown moderate correlations between important clinical, quantitative imaging and function measurements. These correlations reflect the changes that occur between relevant time points and which relate internal structure and external function

Abstract

Introduction. The low-contact stress (LCS) knee prosthesis is a mobile-bearing design with modifications to the tibial component that allow for meniscal-bearing (MB) or rotating-platform (RP). The MB design had nonconstrained anteroposterior and rotational movement, and the RP design has only nonconstrained rotational movement. The anterior soft tissues, including patellar tendon (PT), prevent anterior dislocation of the MB. The PT may consistently be exposed to overstressing. Therefore, we hypothesized that the PT thickness and width in MB prosthesis revealed more morphological changes than those of RP prosthesis due to degeneration of the PT induced by much mechanical stress of the MB movement. To confirm this hypothesis, we analyze the PT thickness and width induced by mobile-bearing inserts. Objectives. Sixty LCS prostheses in 30 patients were analyzed. The average follow-up time was 61 months. MB prosthesis was used on one side of the knee and RP prosthesis was used on the contralateral side of the knee. All patients were chosen from group with no clinical complication, and all had achieved passive full extension and at least 90°of flexion. The average Hospital for Special Surgery Score was 94.6 ± 2.7. Methods. We measured the thickness and width of PT at joint line level, which were confirmed by sagittal section using ultrasound in knee extension between MB and RP design prosthesis. Results. The mean thickness of PT was 4.7 mm (1.2) with MB and 4.7 mm (1.0) with RP design prosthesis. The mean width of PT was 30.6 mm (3.2) with MB and 31.3 mm (3.5) with RP design prosthesis. No significant differences were found between both groups. Conclusion. The current results showed that the PT thickness and width in MB prosthesis did not reveal more morphological changes than those of RP prosthesis due to degeneration of the PT induced by much mechanical stress of the MB movement. The possible reasons are the following: (1) We did not remove infra-patellar fat pad, which might play shock absorber of mechanical stress from MB, and prevent from significant degeneration of PT, (2) MB inserts did not stimulate the middle of the PT directly, unlike LCS A/P-Glide inserts, and might come into contact with the both ends of the PT and (3) MB inserts did not move so as to cause degeneration in the PT

The aim of this longitudinal study is to compare the clinical outcomes of endoscopic ACL reconstruction with either a 4-strand HT or PT autograft over a 5-year period. 90 patients with isolated ACL rupture received PT autograft and 90 received HT autograft were studied annually for 5 years. Assessment included the IKDC Knee Ligament Evaluation, KT1000, Lysholm Knee Score, thigh atrophy, kneeling pain, hamstring pain and radiographs. The median Lysholm Knee Score was 96 for the PT group and 95 for the HT group. No significant difference was found for subjective knee function, overall IKDC assessment, Xray findings, manual ligament KT1000 instrumented testing, graft rupture or contralateral ACL rupture. There was an increasing incidence of fixed flex-ion deformity seen in the PT group. There was no difference in the requirement for subsequent surgery. The incidence of kneeling pain at 5 years was significantly higher in the PT group. Endoscopic reconstruction of the ACL utilizing either autograft can restore knee stability and is menisco protective despite a high level of sporting activity. We did find a worrying trend towards an increasing incidence of fixed flexion deformity with time in the patellar tendon group. Kneeling pain also remains a persistent problem in this subgroup

Purpose: The optimal autograft choice for ACL reconstruction remains controversial. Twelve recently published reviews comparing Patellar Tendon (PT) to Hamstring Tendon (HT) autografts in ACL reconstruction vary in their methodology, quality and application of sensitivity analyses. The present review and meta-analysis follows the rigorous methodology of the Cochrane Collaboration of Systematic Reviews and includes more recent trials that utilize modern surgical techniques and concealed randomization. Method: Randomized Clinical Trials (RCT) and Quasi-randomized Trials (QRCT) with a minimum 2-year follow-up comparing PT with HT autografts in patients undergoing primary ACL reconstruction were included. Non-English articles were professionally translated. Four electronic databases were searched from 1969-present. Bibliographies and proceedings of major orthopaedic meetings were handsearched. Two teams of investigators independently reviewed all citations, selected relevant studies, extracted the data and assigned quality scores. Consensus was achieved within and between each team for all stages of the review process. Results: Three hundred and twenty-six citations were originally identified with the search criteria. Following rigorous review, 26 relevant studies were identified. Nine were excluded due to missing information, inadequate follow-up, ongoing trials or low quality scores, leaving 17 studies included in the final analysis. Outcomes related to stability (Lachman test, instrumented laxity, and pivot shift) showed trends towards improved stability with PT reconstruction. When QRCTs were excluded there was a significant difference favoring PT reconstructions only with respect to the pivot shift test. All other outcomes were similar between the PT and HT reconstructions including IKDC categories, anterior knee pain (trend in favor of HT), re-rupture rate, and activity levels. No information was available to distinguish between the outcome of acute and chronic reconstructions, long term information or validated patient based outcomes. Conclusion: The current literature fails to demonstrate significant differences in multiple outcomes comparing PT to HT reconstruction of the ACL. The overall quality of trials is questionable and fails to use validated patient based outcomes or sufficiently long-term results to assess the development of osteoarthritis

We performed a clinical, instrumental and radiographic study on a highly homogeneous series of 100 consecutive patients with unilateral ACL lesion at 7 years of minimum follow up, alternatively assigned to a single bundle reconstruction using patellar tendon (PT) or to a double bundle reconstruction using hamstrings (DB). Mean Tegner score was 4,8 for PT and 6,5 for DB (p=0,0005). Time for sport resumption was 6,6 months for PT and 3,8 months for DB (p=0,0052). There were no significative differences between the two groups regarding range of motion and functional subjective self-evaluation. Mean anterior displacement at instrumental evaluation performed with KT2000 showed no significative differences between the two groups. Objective clinical evaluation with IKDC was superior for DB group (A=86,5%; B=13,5%) respect to PT group (A=18,7%; B=75%; C=6,3%) (p< 0,0001). We found no differences regarding anterior knee pain between and Ahlback radiographic score the two groups and we have observed no recurrence of instability after surgical treatment. Double bundle ACL reconstruction with hamstrings has showed higher results respect to single bundle ACL reconstruction with patellar tendon in terms of Tegner score, IKDC, time for sport resumption

Purpose of the study: The objective was to compare the results of ligamentoplasties with two commonly used grafts, hamstring and patellar tendon. This was a prospective randomized study. Material and methods: Between January 2001 and June 2004, 98 patients with an acute or chronic anterior cruciate ligament (ACL) tear with joint instability were included in this randomized study for arthroscopic repair. Patients were randomized to the patellar or hamstring arm. Clinical assessment was based on laxity, IKDC score, Lyscholm score, pain visual analog scale (VAS), midthigh thickness and isokinetic assessment at three months. Measurements were recorded preoperatively and at 1, 3, 6 weeks and 3, 6, and 12 months. Results: The two groups were comparable regarding gender, morphotype, associated lesions, and activity level. There was no difference in operative time or in recovery of complete extension. Anterior laxity was the same in the two groups. The isokinetic deficit appeared to be greater in the bone-tendon-bone group at three months. The IKDC and Lysholm scores were not significantly different at six and twelve months. Harvesting site morbidity was more pronounced in the bone-tendon-bone group. Conclusion: The two techniques provide good results. The bone-tendon-bone technique appears to cause greater harvesting site morbidity. While the isokinetic results appear to be better in the hamstring group, the measurements of laxity and recovery of stability did not show any difference

Among the variety of differential diagnoses for chronic patellar tendinopathy, isolated tuberculosis is extremely rare. We report such a case, without any evident primary contiguous or distant focus, in a 31-year-old immunocompetent male.

This prospective longitudinal study compares the results of isolated endoscopic ACL reconstruction utilizing 4-strand hamstring tendon (HT) or patellar tendon (PT) autograft over a 15-year period with respect to re-injury, clinical outcomes and the development of osteoarthritis. 90 consecutive patients with isolated ACL rupture were reconstructed with a PT autograft and 90 patients received HT autograft, with an identical surgical technique. Patients were assessed at 2, 5, 7, 10 and 15 years. Assessment included the IKDC Knee Ligament Evaluation including radiographic evaluation, KT1000, Lysholm Knee Score, kneeling pain, and clinical outcomes. Subjects who received the PT graft had significantly worse outcomes compared to those who received the HT graft at 15 years for the variables of radiologically detectable osteoarthritis (p=0.03), motion loss (p=0.01), single leg hop test (p=0.002), participation in strenuous activity (p=0.05), and kneeling pain (p=0.04). There was no significant difference between the HT and PT groups in overall IKDC grade (p=0.31). ACL graft rupture occurred in 16% of HT group and 8% of the PT group (p=0.07). ACL graft rupture was associated with non-ideal tunnel position (odds ratio 5.0) and males (odds ratio 3.2). Contralateral ACL rupture occurred in significantly more PT patients (24%) than HT patients (12%) (p=0.03), and was associated with age < 18 years (odds ratio 4.1) and the patellar tendon graft (odds ratio 2.6). Radiologically detectable osteoarthritis at 15 years was associated with the PT graft (odds ratio 2.3). Significant differences have developed in the groups at 15 years after surgery which were not seen at earlier reviews. Compared to the HT Group, the PT group had significantly worse outcomes with respect to radiological osteoarthritis, extension loss and functional tests but no significant difference in laxity was identified. There was a high incidence of ACL injury after reconstruction, to both the reconstructed and the contralateral knee

Aim: To compare, in a longitudinal study, the clinical outcomes of endoscopic anterior cruciate ligament (ACL) reconstruction with either a four-strand hamstring tendon (HT) or a patellar tendon (PT) autograft over a five-year period, when a similar operative procedure is followed for both groups. Method: Ninety patients with isolated ACL ruptures who had received PT autografts and another 90 who had received HT autografts were studied annually for five years. Fifty patients were randomised as a subgroup. The assessments included the IKDC Knee Ligament Evaluation, KT1000, Lysholm Knee Score, thigh atrophy, kneeling pain, hamstring pain and radiographs. Results: The median Lysholm Knee Score was 96 for the PT group and 95 for the HT group. No significant difference was found for subjective knee function, overall IKDC assessment, X-ray findings, manual ligament KT1000 instrumented testing, graft rupture or contra-lateral ACL rupture. There was an increasing incidence of fixed flexion deformity seen in the PT group. There was no difference in the requirement for subsequent surgery. The incidence of kneeling pain at five years was significantly higher in the PT group. The results of the randomised patients were identical to the sequential patients. Conclusions: Endoscopic reconstruction of the ACL utilizing either type of autograft restored knee stability and was protective of the meniscus despite a high level of sporting activity. We found a worrying trend towards an increasing incidence of fixed flexion deformity with time in the PT group. Pain when kneeling also remained a persistent problem in this subgroup. PT grafts appeared tighter clinically and, with the KT 1000, when assessed up to three years post operatively, compared with HT grafts. Thereafter the results were similar

Purpose: The purpose of this study was to compare, at ten years follow-up, the clinical and radiological results obtained in two series of patients who underwent patellar tendon ligmentoplasty for anterior cruciate ligament tears. One series was operated in an acute setting (before 45 days) and the other for chronic lesions. Material and methods: In 1986 and 1987, we performed patellar ligamentoplasty for anterior cruciate ligament tears in 230 knees. Mean delay to surgery was ten days for 77 knees (53 reviewed with clinical and radiological evaluation and 12 with questionnaires, i.e. 84%). For 153 knees surgery was performed for chronic lesions (107 reviewed with clinical and radiological evaluation and 12 with questionnaires, i.e. 77%). The IKDC chart was used to assess outcome with KT 2000 measurements on the loaded images. Results: There was a significant difference between the two series for: overt meniscal tears at the time of surgery (58% in the chronic series and 11% in the acute series, p < < 1%); osteoarthritic (26% chronic versus 6% acute, p < 1%); overall IKDC score (96% for acute versus 84% for chronic, p < 3%). The same was true for subjective assessment (normal for 95% of the acute knees versus 65% for the chronic knees) and for rate of recurrent tears (2% for acute and 9% for chronic). There was no significant difference between the series for clinical signs (pain, swelling, apprehension), mean residual laxity as measured by KT 2000, although it was greater for the chronic knees (+2.6%) than for the acute knees (+2.3%). Permanent flexion was not significantly different between the series (31% for chronic and 28% for acute) although the reason was different since for the chronic series, subsequent meniscectomy was necessary. Conclusion: Patellar ligamentoplasty performed in an acute setting provides better clinical and radiological outcome. It stabilises the knee better before possible development of a meniscal lesion that may precipitate osteoarthritis

The choice of graft for anterior cruciate ligament reconstruction remains controversial. A systematic review was performed to compare bone-patella tendon-bone and 4-strand hamstring grafts. Medline (1966 onwards), EMBASE (1980 onwards) and the Cochrane database were searched retrieving 6312 possible articles but only 6 studies fulfilled all the inclusion criteria. To be included, the study had to be prospective, randomised or quasi-randomised, comparing 4SHS and central third BPTB autografts, inserted using an arthroscopically assisted technique and have a minimum 2-year follow up for all patients. These studies recruited 526 patients and 475 were followed for at least 2 years with 235 patients receiving a bone-patella tendon-bone graft and 240 receiving a 4-strand hamstring graft. Overall, there was a greater chance of extension loss (p=0.007) and a trend towards increased patellofemoral joint pain (p=0.09) with a patella tendon graft. With a 4-strand hamstring graft there is a greater loss of hamstring power (p=0.008) and a trend towards an increased chance of a pivot shift > 1 (p=0.12). There was no difference between the 2 groups in terms of lachman testing, chance of returning to the same level of sport, clinical knee scores, graft ruptures or other complications.

The aim of this study was to analyse the gait pattern, muscle force and functional outcome of patients who had undergone replacement of the proximal tibia for tumour and alloplastic reconstruction of the extensor mechanism using the patellar-loop technique.

Between February 1998 and December 2009, we carried out wide local excision of a primary sarcoma of the proximal tibia, proximal tibial replacement and reconstruction of the extensor mechanism using the patellar-loop technique in 18 patients. Of these, nine were available for evaluation after a mean of 11.6 years (0.5 to 21.6). The strength of the knee extensors was measured using an Isobex machine and gait analysis was undertaken in our gait assessment laboratory. Functional outcome was assessed using the American Knee Society (AKS) and Musculoskeletal Tumor Society (MSTS) scores.

The gait pattern of the patients differed in ground contact time, flexion heel strike, maximal flexion loading response and total sagittal plane excursion. The mean maximum active flexion was 91° (30° to 110°). The overall mean extensor lag was 1° (0° to 5°). The mean extensor muscle strength was 25.8% (8.3% to 90.3%) of that in the non-operated leg (p < 0.001). The mean functional scores were 68.7% (43.4% to 83.3%) (MSTS) and 71.1 (30 to 90) (AKS functional score).

In summary, the results show that reconstruction of the extensor mechanism using this technique gives good biomechanical and functional results. The patients’ gait pattern is close to normal, except for a somewhat stiff knee gait pattern. The strength of the extensor mechanism is reduced, but sufficient for walking.

Cite this article: Bone Joint J 2015;97-B:1063–9.

At first-stage revision surgery for infection of total knee arthroplasties, antibiotic-impregnated cement spacers are frequently implanted. Two types of cement spacers are commonly used, “static” and “articulating” cement spacers. Advocates of cement spacers state that they deliver high doses of antibiotics locally, increase patient comfort, allow mobility and provide joint stability. They also minimize contracture of collateral ligaments, thereby facilitating re-implantation of a definitive prosthesis at a later stage. The use of these cement spacers, however, are not without significant complications, including patella tendon injuries.

We describe a series of three patients who sustained patella tendon injuries in infected total knee arthroplasties following the use of a static cement spacer at first-stage knee revision.

The patella tendon injuries resulted in significant compromise to wound healing and knee stability requiring multiple surgeries. The mid-term function was poor with an Oxford score at 24 months ranging from 12–20

Based on our experience, we advise caution in the use of static cement spacer blocks. If they are to be used, we recommend that they should be keyed in the bone to prevent patella tendon injuries.

The choice of graft for anterior cruciate ligament reconstruction remains controversial. A systematic review was performed to compare bone-patella tendon-bone and 4-strand hamstring grafts. Medline (1966 onwards), EMBASE (1980 onwards) and the Cochrane database were searched retrieving 6312 possible articles but only 6 studies fulfilled all the inclusion criteria. To be included, the study had to be prospective, randomised or quasirandomised, comparing 4SHS and central third BPTB autografts, inserted using an arthroscopically assisted technique and have a minimum 2-year follow up for all patients. These studies recruited 526 patients and 475 were followed for at least 2 years with 235 patients receiving a bone-patella tendon-bone graft and 240 receiving a 4-strand hamstring graft. Overall, there was a greater chance of extension loss (p=0.007) and a trend towards increased patellofemoral joint pain (p=0.09) with a patella tendon graft. With a 4-strand hamstring graft there is a greater loss of hamstring power (p=0.008) and a trend towards an increased chance of a pivot shift > 1 (p=0.12). There was no difference between the 2 groups in terms of lachman testing, chance of returning to the same level of sport, clinical knee scores, graft ruptures or other complications.

Cryopreserved patellar tendon allografts are often recommended for reconstruction of anterior cruciate ligaments (ACLs) because living donor fibroblasts are thought to promote repair. Animal studies, however, indicate that ligaments regenerate from recipient rather than donor cells. If applicable to man, these observations suggest that allograft cell viability is unimportant. We therefore used short tandem repeat analysis with polymerase chain reaction (PCR) amplification to determine the source of cells in nine human ACLs reconstructed with cryopreserved patellar tendon allografts. PCR amplification of donor and recipient DNA obtained before operation and DNA from the graft obtained two to ten months after transplantation revealed the genotype of cells and showed only recipient cells in the graft area. Rather than preserve the viability of donor cells, a technique is required which will facilitate the introduction of recipient cells into patellar tendon allografts.

Purpose: The purpose of this study was to compare the bone-patellar-tendon-bone (BPTB) and the four-strand hamstring grafts for anterior cruciate ligament (ACL) reconstruction in patients aged less than 40 years and to evaluate the influence of meniscectomies performed before, during, or after the ACL reconstruction.

Material and methods: Between March 1997 and March 2000, 114 patients who underwent ACL reconstruction (58 BPTB then 56 hamstring) were included. Exclusion criteria were: peripheral ligament repair or associated bone procedures, surgical revision. The continuous series was analysed retrospectively by two surgeons different from the operator. The BTPB group included 58 patients (mean age 28 years) evaluated at a mean 44 months; meniscectomy was associated in eleven cases. The hamstring group included 56 patients (mean age 27.5 years) evaluated at a mean 28 months; there were 19 associated meniscectomies. The IKDC score and laxity (KT2000, Telos) as well as the radiological aspect (AP, lateral and 30° flexion views) were used to assess outcome.

Results: At last follow-up (89 patients, 78%) there were three failures in each group; 77% of patients were in IKDC classes A or B. Subjectively, 90% of the patients considered their knee was normal or nearly normal. For both types of grafts, the outcome was significantly better if the meniscus was preserved. For knees with preserved menisci, there was no difference between BTPB and hamstring reconstruction. Anterior pain was greater after BTPB and posterior thigh pain was greater after hamstring reconstruction. Mean deficit was 14% in extension force in the BTPB group and 25% in flexion force in the hamstring group.

Discussion: Meniscectomy before, during or after ACL reconstruction has a negative effect on the graft outcome for both techniques. If the meniscus is preserved, there is no difference between BTPB and hamstring reconstruction; the morbidities are different, but equivalent (anterior pain for BTPB and posterior for hamstring) and muscle deficit is different (extension for BTPB and flexion for hamstring).

Conclusion: More important than the type of transplant used to reconstruct the ACL, meniscal preservation is a major element affecting outcome.

Introduction: The aim of this study was to evaluate the anterior knee symptoms after anterior cruciate ligament reconstruction (ACL) using either pateller tendon (PT) or hamstring tendon (HS) autograft.

Materials and Methods: 45 patients undergoing primary ACL reconstruction were randomized to have a PT (23 patients) or a doubled HS (22 patients). Patients were reviewed after 3, 6, and 9 months. Patients were examined for knee pain and sensory changes in the anterior aspect of the knee, the ability for kneeling and sensitivity of the surgical incision.

Results: At the last follow-up in the PT group 4 patients (17%) had anterior knee pain, knee-walking test was impossible for 4 patients (17%), 3 patients (13%) reported to have surgical incision sensitivity and 4 patients (17%) had numbness in the skin area supplied by the infrapatellar branch of the saphenous nerve. In the HS group, 2 patients (9%) had anterior knee pain, knee-walking test was impossible for 2 patients (9%), 2 patients (9%) reported to have surgical incision sensitivity and 10 patients (45%) had numbness in the skin area supplied by the infrapatellar branch of the saphe-nous nerve. There was a statistical significant difference (p< 0.05) regarding the sensory changes in the anterior aspect of the knee.

Conclusions: Harvesting of the PT or HS autograft for ACL reconstruction is associated with a low rate of anterior knee symptoms. Sensory changes following HS harvesting is significantly higher. However, this does not appear to be of great clinical importance without limitation of activities.

Patellar tendinosis (PT) is common and can result in prolonged disability, especially in jumping athletes. Recently developed ultra-short-echo (UTE) MRI sequences allow for quantitative evaluation of tendon biostructure with T2* relaxometry. This study evaluated the relationships between changes over time (COT) in quantitative T2*-metrics, qualitative PT grades, and patient reported symptoms within 10 male basketball players from a single collegiate basketball team. All subjects completed weekly VISA-P symptomology questionnaires over the basketball season. Bilateral 3-Tesla MRIs (GE Healthcare) were obtained at pre- and post-season study visits. High-resolution, PD-weighted, FSE sequences were used to qualitatively grade PT. Quantitative T2*-metrics were evaluated using high-resolution, 3D, multi-echo, UTE-MRI sequences. Bilinear exponential fits of SI to corresponding echo time were used to calculate T2*-metrics. All qualitative and quantitative evaluations were region specific (proximal, middle, distal). Linear mixed effects models assessed associations of side and region with T2*-metrics. Spearman correlations evaluated relationships between outcome measures. Within and between study visits, significant side-to-side differences in T2*-metrics were found and were significantly impacted by leg dominance (p<0.05). Pre-season T2*-metrics correlated with COT in T2*-metrics, COT in T2*-metrics correlated with COT in qualitative PT grades, and post-season T2*-metrics correlated with max changes in VISA-P scores (ρ≥0.64). Quantitative T2*-metrics can detect PT and may be capable of predicting the onset of pathology. T2*-metrics could benefit the clinical management of PT: it is sensitive to changes in pathologic severity over time, and therefore can serve as a quantitative metric to guide treatment and evaluate intervention efficacy.

This study of collegiate basketball players evaluated change over time (COT) in ultrasound shear wave (SW) elastography metrics across the basketball season, and correlated to morphologic changes on conventional ultrasound imaging, and VISA-P scores. In eleven male collegiate basketball players (mean age 19, age range 18–21), patella tendon (PT) ultrasound and SW elastography of both knees were performed at pre-season and post-season time points, and players reported their VISA-P scores throughout the season. Patella tendinopathy grade and SW metrics were correlated to VISA-P scores using Spearman correlation coefficients. Paired t-test was used to assess differences in mean SW metrics at pre-and post-season timepoints, accounting for leg dominance. 6 of 11 players (54.5%) had baseline patella tendinopathy on ultrasound progressing in 4 players. The mean change in VISA-P score was 15.18 (+/−8.55). No significant correlation was seen between ultrasound grades of tendinopathy and VISA-P. Pre-season SW velocities did not significantly correlate with baseline VISA-P scores. Post-season SW values and SW COT demonstrated strong correlation with change in VISA-P score in dominant and non-dominant knees. Although not statistically significant, there was a trend towards higher SW velocity for tendinopathy in both dominant and non-dominant knees at both study visits. SW metrics of the PT correlated to change in VISA-P scores in the dominant and non-dominant knees, whereas conventional ultrasound grades of patella tendinopathy did not. There was a trend towards higher SW velocities in patella tendinopathy which may indicate detection of change in intrinsic tissue stiffness.

Infrapatellar Contracture Syndrome describes a postoperative complication characterised by a vertical migration of the patella due to Patella Tendon (PT) shortening and/or PT adhesion (PTA) formation. We investigated how removal of the central one-third of the PT influences both PT length (LP) and in vitro knee kinematics in 18 sheep divided into 3, 6, 12 and 24 week groups. At time of sacrifice the pelvis-lower extremities complexes were left in a supine position until rigor mortis set in. Limbs were CT-scanned (0.5mm) whilst frozen and LP measured (ProEngineer, PTC, MA). Specimens were fixed into a loading frame with 50N applied to the rectus femoris and knee kinematics obtained (Polhemus, VT). Bones and associated registration block portions of the receiver assemblies were CT-scanned (0.5mm), reconstructed, and imported into ProEngineer where coordinate systems were created in accordance with the Joint Coordinate System (JCS). Registration was accomplished by aligning models of the receiver assemblies with the reconstructed surfaces. Post-processing and statistical analysis (ANOVA) was performed using Matlab (MathWorks, MA) and data referenced to the contralateral controls.

No significant changes in LP were observed. The mean PT length ratio (LP/LC) in the 3 week group was 1.0028±0.004 (mean±SD). In the 6 week group this ratio had increased to 1.0282±0.0246, returning to 1.005±0.0035 at 12 weeks and back to 1.0159±0.0217 at 24 weeks. No PTA’s were observed. A significant proximal shift of the patella reflecting the increase in LP was observed which correlated well with a retardation of patellar flexion (r = 0.880, p< 0.001). A significant decrease in medial patellar tilt was also observed but was not coupled with changes in tibial rotation. Proximal and lateral tibial shifts were also detected.

The results of this study seem to suggest that the changes in knee kinematics and LP induced by removal of the central one-third of the PT do not recover 24 weeks post-operatively.

Press-fit fixation technique in anterior cruciate ligament (ACL) reconstruction has recently gained popularity. The objective of this study was to evaluate the initial fixation strength of human patellar tendon-bone (PTB) grafts with respect to bone-plug length and loading angle by using a femoral press-fit fixation technique.

Fourty-eight human PTB-grafts were obtained from 24 fresh frozen cadavers (mean age 72 years). The specimens were randomly assigned to two experimental groups: One with a 15 mm (n=24) and a second with a 25 mm patellar bone plug (n=24). The grafts were implanted to porcine femora in a press-fit fixation technique. Ultimate failure loads were measured at 10 mm/s at varying loading angles of 0, 30 and 60.

Biomechanical testing showed a significant difference of ultimate failure load comparing 15 mm (mean 236 N) to 25 mm (mean 333 N) bone plugs (p=0.015). In both groups, the fixation strength increased with rising loading angles. While axial graft loading exclusively caused plug dislocation, the predominant mode of failure was tendon rupture at 60 loading angle.

It is concluded that bone plug length and loading angle significantly influence the primary stability of PTB press-fit fixation in ACL reconstruction. Based on these findings, we recommend the use of patellar bone plugs with a minimum of 25 mm in length. If graft harvesting occasionally generates a patellar bone plug measuring 15 mm, restrictive postoperative rehabilitation should be advised.

Aim: The aim of our study was to compare the results of primary ACL reconstruction, performed in our department with deep frozen allogenic BTB graft to the results with autogenic BTB graft. Patients and Method: From the 1st January, 1996 to 31st December, 2001 81 ACL reconstruction on 78 patients (17 female, 61 male) were performed. The average age of our patients was 25.6 years (14.5 – 46 years). There were 56 ACL plasties on 54 patients (13 female, 41 male) where allogenic BTB graft was used and 25 cases on 24 patients (4 female, 20 male) where autogenic BTB graft was used. The average follow up time was 37 months (12–82 months). All the surgeries were performed with arthroscopic technique. Results: We had the chance to follow up 46 knees of 44 patients in the allogenic group, and 20 knees of 21 patients in the group where autogenic BTB graft was used. The results were analysed with the help of the Lysholm, Tegner and IKDC scores. There were no significant differences found between the two groups according to these scores. In the group where allogenic BTB graft was used for the primary ACL plasty neither rejection of the graft nor immune synovitis were observed. Transmission of infectious diseases (hepatitis C, HIV, etc.) were not observed either. The cosmetic results were better (postoperative scar was smaller) and there where no donor site problems. Conclusion: Comparing our results using deep frozen BTB allogenic graft with the results after BTB autograft, we suggest the use of the allogenic BTB grafts in selected cases. It is proposed, because the results are relatively good and there where no specific complications found (e.g. rejection of the graft, immune synovitis etc.) for this type of graft.

Purpose: To evaluate knee proprioception following Anterior Cruciate Ligament (ACL) reconstruction using two different autografts.

Materials and methods: Forty patients, (34 male, 6 female), aged between 17–54 years old (mean: 31), with complete ACL tears were subjected to ligamentous reconstruction. Group A (20 patients) underwent reconstruction with 4 strand hamstrings graft whilst in the remaining 20 patients (group B) bone-patellar tendon-bone graft was used. Proprioception was assessed by the Joint Position Sense (JPS) of the knee for predetermined angles (15°, 45° and 75°) as well as by the threshold to detection of passive movement (TTDPM) at 15° and 45° in flexion and extension using an isokinetic dynamometer (Con-Trex, MJ, Switzerland). The examination was performed pre-operatively and 3, 6 and 12 months after surgery, on both knees of all patients.

The t-test was utilised for statistical analysis.

Results: ACL deficient knees presented with significantly poor TTDPM values at a starting angle of 15° moving into flexion and extension. The JPS findings were statistically different between injured and uninjured knees (p< 0.05).

The TTDPM at 15° and JPS findings of the injured leg, before and 6, 12 months after reconstructive surgery, were statistically different (p< 0.05) for both groups.

There was no statistically significant difference for both JPS and TTDPM at 15° in flexion and extension between the findings in reconstructed and uninjured knees, at 6 and 12 months post-operatively in both groups.

No difference was found when comparing proprioceptive improvement following ACL reconstruction between the two different autograft groups.

Conclusions: Both JPS at 15°, 45°, and 75° and TTDPM at 15° in flexion and extension are impaired in ACL deficient knees. There is improvement of these proprioceptive parameters following operative reconstruction of the ACL using both hamstrings and patellar tendon grafts. No particular graft seems to be preferable in terms of proprioceptive improvement as assessed by JPS and TTDPM.

Objectives. Posterior condylar offset (PCO) and posterior tibial slope (PTS) are critical factors in total knee arthroplasty (TKA). A computational simulation was performed to evaluate the biomechanical effect of PCO and PTS on cruciate retaining TKA. Methods. We generated a subject-specific computational model followed by the development of ± 1 mm, ± 2 mm and ± 3 mm PCO models in the posterior direction, and -3°, 0°, 3° and 6° PTS models with each of the PCO models. Using a validated finite element (FE) model, we investigated the influence of the changes in PCO and PTS on the contact stress in the patellar button and the forces on the posterior cruciate ligament (PCL), patellar tendon and quadriceps muscles under the deep knee-bend loading conditions. Results. Contact stress on the patellar button increased and decreased as PCO translated to the anterior and posterior directions, respectively. In addition, contact stress on the patellar button decreased as PTS increased. These trends were consistent in the FE models with altered PCO. Higher quadriceps muscle and patellar tendon force are required as PCO translated in the anterior direction with an equivalent flexion angle. However, as PTS increased, quadriceps muscle and patellar tendon force reduced in each PCO condition. The forces exerted on the PCL increased as PCO translated to the posterior direction and decreased as PTS increased. Conclusion. The change in PCO alternatively provided positive and negative biomechanical effects, but it led to a reduction in a negative biomechanical effect as PTS increased. Cite this article: K-T. Kang, Y-G. Koh, J. Son, O-R. Kwon, J-S. Lee, S. K. Kwon. A computational simulation study to determine the biomechanical influence of posterior condylar offset and tibial slope in cruciate retaining total knee arthroplasty. Bone Joint Res 2018;7:69–78. DOI: 10.1302/2046-3758.71.BJR-2017-0143.R1

Introduction. With an ongoing increase in total knee arthroplasty (TKA) procedural volume, there is an increased demand to improve surgical techniques to achieve ideal outcomes. Considerations of how to improve post-operative outcomes have included preservation of the infrapatellar fat pad (IPFP). Although this structure is commonly resected during TKA procedures, there is inconsistency in the literature and among surgeons regarding whether resection or preservation of the IPFP should be achieved. Additionally, information about how surgical handling of the IPFP influences outcomes is variable. Therefore, the purpose of this systematic review was to evaluate the influence of IPFP resection and preservation on post-operative flexion, pain, Insall-Salvati Ratio (ISR), Knee Society Score (KSS), patellar tendon length (PTL), and satisfaction in primary TKA. Methods. A systematic literature search was performed to retrieve all reports that evaluated IPFP resection or preservation during total knee arthroplasty (TKA). The following databases were queried: PubMed, EBSCO host, and SCOPUS, resulting in 488 unique reports. Two reviewers independently reviewed the studies for eligibility based on pre-established inclusion and exclusion criteria. A total of 11 studies were identified for final analysis. Patient demographics, type of surgical intervention, follow-up duration, and clinical outcome measures were collected and further analyzed. This systematic review reported on 11,996 total cases. Complete resection was implemented in 3,723 cases (31%), partial resection in 5,458 cases (45.5%), and preservation of the IPFP occurred in 2,815 cases (23.5%). Clinical outcome measures included patellar tendon length (PTL) (5 studies), knee flexion (4 studies), pain (6 studies), Knee Society Score (KSS) (3 studies), Insall-Salvati Ratio (ISR) (3 studies), and patient satisfaction (1 study). Results. There were no differences found following IPFP resection for patient satisfaction (p=0.92), ISR (all p-values >0.05), and KSS (all p-values >0.05). Mixed evidence was found for patellar tendon length, pain, and knee flexion following IPFP resection vs. preservation. Conclusion. Given the current literature and available data, there were several clinical outcome measures that indicated better patient results with preservation of IPFP during primary TKA in comparison to the resection of IPFP. Specifically, resection resulted in inferior outcomes for patellar tendon length, knee flexion, and pain measurements. However, more extensive research is needed to better determine that preservation is the superior surgical decision. This includes a need for more randomized controlled trials (RCTs). Future studies should focus on conditions in which preservation or resection of IPFP would be best indicated during TKA in order to establish guidelines for best surgical outcomes in those patients. For any figures or tables, please contact authors directly

Like all surgery, if you can see it, you can usually get the job done. This is especially true for extracting well-fixed components, as iatrogenic bone loss is a serious consideration regarding the reconstruction challenge. While reasons for revision are varied, several general principles are useful to consider during the pre and peri-operative course. Pre-operatively, forewarned is forearmed. Certain factors pre-operatively can suggest the degree of operative difficulty regarding exposure. Revisions for stiffness obviously would suggest difficulty with exposure. Revisions in knees with patellar baja are almost always challenging as the patella is difficult to evert. When revising infected knees, an exuberant synovial response can result in beefy, friable synovium that has a volume effect with decreased tissue compliance. Further, the hyperemic friable tissue bleeds easily, even with tourniquet, and is difficult to anticoagulate. Peri-operatively, the general principles to consider are as follows: 1) Don't rush exposure. Good exposure is the result of a series of deliberate and sequential steps that safely reduce tissue volume and improvement in tissue compliance. These steps include in almost all cases: a. Extend the incision as necessary, there is no call for minimally invasive revision knee surgery; b. Tenolysis of the patellar tendon; c. Clearing of the medial and lateral gutter; d. Clearing of the flexion space; e. Clearing of quadriceps adhesions. 2) Protect the extensor mechanism, above all else. Carefully monitor the insertion of the patellar tendon when beginning to flex the knee. If an avulsion begins, back off flexion and spend more time on clearing of scar tissue, as above. If still unsuccessful, then extensile exposure should be considered, such as a quadriceps snip. Be especially careful when osteolysis is present around the tibial tubercle. 3) The most difficult area to of the knee to expose in revision surgery is the posterior lateral corner, resulting in difficulty in exposing the posterior lateral femur and the posterior corner of the tibial component. Extensile exposures do not necessarily result in complete exposure of these regions. Redoubling efforts to remove scar tissue is often more successful. Bovie dissection of soft tissue on the proximal medial tibia can assist, with extension back to the semimembranosus insertion sometimes being necessary. While adequate exposure can result because of the increased ability to externally rotate the tibia, this exposure can also destabilise the medial side of the knee, sometimes resulting in the need to add constraint. The pros and cons need to be considered on a case-by-case basis. 4) Be judicious in the utilization of extensile exposures, and choose the exposure technique best suited for the situation. If the patellar tendon is normal, consider a simple quadriceps snip. If the knee is particularly stiff or the tibial tubercle or patellar tendon insertion is in jeopardy, then the snip can be extended into a V-Y turndown. If the patellar tendon is contracted resulting in patellar baja, then a tibial tubercle osteotomy (TTO) can be considered. Careful removal of tissue in scar tissue, as above, allows for relative external rotation of the tibia on the femur that translates the patella laterally, reducing the need for TTO. TTO can also be effective when approaching a cemented tibial stem

Tendons are characterised by an inferior healing capacity when compared to other tissues, ultimately resulting in the formation of a pathologically altered extracellular matrix structure. Although our understanding of the underlying causes for the development and progression of tendinopathies remains incomplete, mounting evidence indicates a coordinated interplay between tendon-resident cells and the ECM is critical. Our recent results demonstrate that the matricellular protein SPARC (Secreted protein acidic and rich in cysteine) is essential for regulating tendon tissue homeostasis and maturation by modulating the tissue mechanical properties and aiding in collagen fibrillogenesis [1,2]. Consequently, we speculate that SPARC may also be relevant for tendon healing. In a rat patellar tendon window defect model, we investigated whether the administration of recombinant SPARC protein can modulate tendon healing. Besides the increased mRNA expression of collagen type 1 and the downregulation of collagen type 3, a robust increase in the expression of pro-regenerative fibroblast markers in the repair tissue after a single treatment with rSPARC protein was observed. Additionally, pro-fibrotic markers were significantly decreased by the administration of rSPARC. Determination of structural characteristics was also assessed, indicating that the ECM structure can be improved by the application of rSPARC protein. Therefore, we believe that SPARC plays an important role for tendon healing and the application of recombinant SPARC to tendon defects has great potential to improve functional tendon repair

Many recent knee prostheses are designed aiming to the physiological knee kinematics on tibiofemoral joint, which means the femoral rollback and medial pivot motion. However, there have been few studies how to design a patellar component. Since patella and tibia are connected by a patellar tendon, tibiofemoral and patellofemoral motion or contact forces might affect each other. In this study, we aimed to discuss the optimal design of patellar component and simulated the knee flexion using four types of patellar shape during deep knee flexion. Our simulation model calculates the position/orientation, contact points and contact forces by inputting knee flexion angle, muscle forces and external forces. It can be separated into patellofemoral and tibiofemoral joints. On each joint, calculations are performed using the condition of point contact and force/moment equilibrium. First, patellofemoral was calculated and output patellar tendon force, and tibiofemoral was calculated with patellar tendon force as external force. Then patellofemoral was calculated again, and the calculation was repeated until the position/orientation of tibia converged. We tried four types of patellar shape, circular dome, cylinder, plate and anatomical. Femoral and tibial surfaces are created from Scorpio NRG PS (Stryker Co.). Condition of knee flexion was passive, with constant muscle forces and varying external force acting on tibia. Knee flexion angle was from 80 to 150 degrees. As a result, the internal rotation of tibia varied much by using anatomical or plate patella than dome or cylinder shape. Although patellar contact force did not change much, tibial contact balances were better on dome and cylinder patella and the medial contact forces were larger than lateral on anatomical and plate patella. Thus, the results could be divided into two types, dome/cylinder and plate/anatomical. It might be caused by the variations of patellar rotation angle were large on anatomical and plate patella, though patellar tilt angles were similar in all the cases. We have already reported that the anatomical shape of patella would contact in good medial-lateral balance when tibia moved physiologically, therefore we have predicted the anatomical patella might facilitate the physiological tibiofemoral motion. However, the results were not as we predicted. Actually our previous and this study are not in the same condition; we used a posterior-stabilized type of prosthesis, and the post and cam mechanism could not make the femur roll back during deep knee flexion. It might be better to choose dome or cylinder patella to obtain the stability of tibiofemoral joint, and to choose anatomical or plate to the mobility

Purpose To ascertain whether there are differences in the histopathological appearance of tendinopathic Achilles and patellar tendons. Methods In males, we studied biopsies from tendinopathic Achilles (n = 28; average age 34.1 years) and patellar tendons (n = 28; average age 32.1), and Achilles tendons (n = 21; average age 61.8 years) from deceased patients with no known tendon pathology, and patellar tendons (n = 15; average age 28.3) from patients undergoing anterior cruciate ligament reconstruction. Haematoxylineosin stained slides were interpreted using a semi-quantitative grading scale (0: normal to 3: maximally abnormal) for fibre structure; fibre arrangement; rounding of the nuclei; regional variations in cellularity; increased vascularity; decreased collagen stainability; hyalinisation. All slides were assessed blindly twice, the agreement between two readings ranging from 0.170 to 0.750 (Kappa statistics). Results The highest mean score of tendinopathic Achilles tendons was not significantly different from that of tendinopathic patellar tendons (11.6 ± 5 and 10.4 ± 3, respectively). The ability to differentiate between an Achilles tendon and a patellar tendon was low. Conclusions Tendinopathic Achilles and patellar tendons show a similar histological picture. It was not possible to identify whether a specimen had been harvested from an Achilles or a patellar tendon on the basis of histological examination. The general pattern of degeneration was common to both tendinopathic Achilles and patellar tendons. A common, as yet unidentified, etio-pathological mechanism may have acted on both these tendon populations

Tendons display poor intrinsic healing properties and are difficult to treat[1]. Prior in vitro studies[2] have shown that, by targeting the Activin A receptor with magnetic nanoparticles (MNPs), it is possible to remotely induce the tenogenic differentiation of human adipose stem cells (hASCs). In this study, we investigated the tenogenic regenerative potential of remotely-activated MNPs-labelled hASCs in an in vivo rat model. We consider the potential for magnetic controlled nanoparticle mediated tendon repair strategies. hASCs were labelled with 250 nm MNPs functionalized with anti-Activin Receptor IIA antibody. Using a rapid curing fibrin gel as delivery method, the MNPs-labelled cells were delivered into a Ø2 mm rat patellar tendon defect. The receptor was then remotely stimulated by exposing the rats to a variable magnetic gradient (1.28T), using a customised magnetic box. The stimulation was performed 1 hour/day, 3 days/week up to 8 weeks. Tenogenesis, iron deposition and collagen alignment were assessed by histological staining and IHC. Inflammation mediators levels were assessed by ELISA and IHC. The presence of human cells in tendons after 4 and 8 weeks was assessed by FISH analysis. Histological staining showed a more organised collagen arrangement in animals treated with MNPs-labelled cells compared to the controls. IHC showed positive expression of tenomodulin and scleraxis in the experimental groups. Immunostaining for CD45 and CD163 did not detect leukocytes locally, which is consistent with the non-significant levels of the inflammatory cytokines analysis performed on plasma. While no iron deposition was detected in the main organs or in plasma, the FISH analysis showed the presence of human donor cells in rat tendons even after 8 weeks from surgery. Our approach demonstrates in vivo proof of concept for remote control stem cell tendon repair which could ultimately provide injectable solutions for future treatment. We are grateful for ERC Advanced Grant support ERC No.789119, ERC CoG MagTendon No.772817 and FCT grant 2020.01157.CEECIND

Introduction: The mechanobiology and response of bone formation to strain under physiological loading is well established, however investigation into exceedingly soft scaffolds relative to cancellous bone is limited. In this study we designed and 3D printed mechanically-optimised low-stiffness implants, targeting specific strain ranges inducing bone formation and assessed their biological performance in a pre-clinical in vivo load-bearing tibial tuberosity advancement (TTA) model. The TTA model provides an attractive pre-clinical framework to investigate implant osseointegration within an uneven loading environment due to the dominating patellar tendon force. A knee finite element model from ovine CT data was developed to determine physiological target strains from simulated TTA surgery. We 3D printed low-stiffness Ti wedge osteotomy implants with homogeneous stiffness of 0.8 GPa (Ti1), 0.6 GPa (Ti2) and a locally-optimised design with a 0.3 GPa cortex and soft 0.1 GPa core (Ti3), for implantation in a 12-week ovine tibial advancement osteotomy (9mm). We quantitatively assessed bone fusion, bone area, mineral apposition rate and bone formation rate. Optimised Ti3 implants exhibited evenly high strains throughout, despite uneven wedge osteotomy loading. We demonstrated that higher strains above 3.75%, led to greater bone formation. Histomorphometry showed uniform bone ingrowthin optimised Ti3 compared to homogeneous designs (Ti1 and Ti2), and greater bone-implant contact. The greatest bone formation scores were seen in Ti3, followed by Ti2 and Ti1. Results from our study indicate lower stiffness and higher strain ranges than normally achieved in Ti scaffolds stimulate early bone formation. By accounting for loading environments through rational design, implants can be optimised to improve uniform osseointegration. Design and 3D printing of exceedingly soft titanium orthopaedic implants enhance strain induced bone formation and have significant importance in future implant design for knee, hip arthroplasty and treatment of large load-bearing bone defects

A key component to the success of total knee replacement is the health and integrity of the extensor mechanism. While there are issues related to the patella, such as fracture, dislocation, subluxation, clunk due to peripatellar fibrosis and anterior knee pain, the overall integrity of the extensor mechanism is of tantamount importance in providing an excellent functional outcome. During total knee replacement it is of utmost importance to preserve the anatomic insertion of the patellar tendon on the tibial tubercle. However, after total knee replacement, a fall or extreme osteoporosis of the patella may cause a rupture of the patellar tendon, distally or proximally, and possibly the quadriceps tendon off of the proximal pole of the patella. Simple repairs of the patellar tendon avulsion may involve use of the semitendonosis and gracilis tendons along with primary repair of the tendon. Usually, patella infera develops after such a repair affecting overall strength and function. For severe disruptions of the extensor mechanism that are accompanied by a significant extensor lag, autologous tissue repair may not be possible. Thus, there are three techniques for reconstruction of this difficult problem: Extensor mechanism allograft with bone-patellar tendon-patella-quadriceps tendon, extensor mechanism allograft with os calcis-Achilles tendon construct and Marlex-mesh reconstruction for patellar tendon avulsion. The key to success of extensor mechanism allograft is proper tensioning of the allograft at full extensor and immobilisation for 6 weeks. Rosenberg's early experience showed that the allograft works best placed at maximum tension in extension. Rubash has described the use of the os calcis-Achilles tendon which does not utilise a patellar substitute. Hansen has recently described excellent results with the use of Marlex mesh to act as a structural reinforcement to the patellar tendon when it is avulsed

The battle of revision TKA is won or lost with safe, effective, and minimally bony-destructive implant removal, protecting all ligamentous stabilisers of the knee and, most importantly, the extensor mechanism. For exposure, incisions should be long and generous to allow adequate access. A standard medial parapatellar capsular arthrotomy is preferred. A synovectomy is performed followed by debridement of all scar tissue, especially in the medial and lateral gutters. All peripatellar scar tissue is excised followed by release of scar tissue within the patellar tendon, allowing for displacement or everting of the patella. As patellar tendon avulsion at any time of knee surgery yields disastrous results, the surgeon should be continuously evaluating the patellar tendon integrity, especially while displacing/everting the patella and bringing the knee into flexion. If displacement/eversion is difficult, consider rectis-snip, V-Y quadricepsplasty, or tibial tubercle osteotomy. The long-held requisite for patellar eversion prior to component removal is inaccurate. In most cases simple lateral patellar subluxation will provide adequate exposure. If a modular tibial system is involved, removal of the tibial polyethylene will decompress the knee, allowing for easier access to patellar, femoral, and tibial components. For patellar component removal, first identify the border of the patella, then carefully clean and debride the interface, preferably with electrocautery. If the tibial component is cemented all-polyethylene, remove using an oscillating saw at the prosthetic-bone interface. Debride the remaining cement with hand tools, ultrasonic tools, or burrs. Remove the remaining peg using a low-speed burr. If the tibial component is metal-backed, then utilise a thin saw blade or reciprocating saw to negotiate the undersurface of the component between the pegs. If pegs are peripherally located, cut with a diamond disc circular cutting tool. Use a trephine to remove the pegs. For femoral component removal, identify the prosthetic-bone/prosthetic-cement interface then remove soft tissue from the interface, preferably with electrocautery. Disrupt the interface around all aspects of the component, using any of following: Gigli saw for cementless components only, micro saw, standard oscillating saw, reciprocating saw, a series of thin osteotomes, or ultrasonic equipment. If the femoral component is stemmed, remove the component in two segments using an appropriate screwdriver to remove the screw locking the stem to the component. Remove the femoral component with a retrodriver or femoral component extractor. Debride cement with hand tools or burr, using care to avoid bone fracture. If a stem is present, then remove with the appropriate extraction device. If “mismatch” exists, where femoral (or likewise, tibial) boss is smaller in diameter than the stem, creating a cement block prohibiting stem removal, remove the cement with hand tools or burr. If the stem is cemented, use hand tools, ultrasonic tools, or a burr to debride the cement. Curette and clean the canals. For tibial component removal, disrupt the prosthetic-cement/prosthetic-bone interface using an oscillating or reciprocating saw. Gently remove the tibial component with a retrodriver or tibial extractor. If stem extensions are utilised, disengage and debride all proximal cement prior to removing the stem. If stem is present, then remove stem with appropriate extraction device. If stem is grit-blasted and well-fixed, create 8mm burr holes 1.5 to 2.5cm distal to tibial tray on medial aspect and a small divot using burr, then drive implant proximally with Anspach punch. Alternatively, a tibial tubercle osteotomy may be performed. If the stem is cemented, use hand tools, ultrasonic tools or burr to debride cement

Tissue engineering and regenerative medicine (TERM) hold the promise to provide therapies for injured tendons despite the challenging cues of tendon niche and the lack of specific factors to guide regeneration. The emerging potential of magnetic responsiveness and magnetic nanoparticles (MNPs) functionalities offers new perspectives to tackle TERM challenges. Moreover, pulsed electromagnetic field (PEMF) is FDA approved for orthopaedics with potential to control inflammation upon injury. We previously demonstrated that magnetic cell-sheets assisted by PEMF trigger the inflammation resolution by modulating cytokine-enriched environments [1]. To further understand the potential of magnetically assisted living patches, we have recently conducted in vivo studies using a rat patellar defect model. After labeling of human adipose stem cells with iron oxide MNPs for 16h, magCSs were cultured up to 3 days in α-MEM medium under non-magnetic or PEMF conditions. MagCSs were evaluated by immunocytochemistry, and real time RT-PCR for tendon markers. Cell metabolic activity was also assessed by MTS and ECM proteins quantified by Sirius Red/Fast Green. The MagCSs effect in ameliorating healing was assessed after implantation in window defects created in the patellar tendon of rats. PEMF was externally applied (3mT, 70Hz) 3d/week for 1h (magnetotherapy). After 4 and 8w, tendons were histologically characterized for immune-detection of tendon and inflammatory markers, and for Perls van Gieson and HE stains. Blood and detoxification organs were screened for inflammatory mediators and biodistribution of MNPs, respectively. In vitro results suggest that PEMF stimulates cellular metabolic activity, influences protein synthesis and the deposition of collagen and non-collagenous proteins is significantly increased compared to non-magnetic conditions. No adverse reactions, as infection or swelling, were observed after surgery or during follow-up. After 8w, magCSs remained at the implantation site and no MNPs were detected on detoxification organs. Plasma levels of IL1α, β, IL6 and TNFα assessed by multiplex assay were below detectable values (<12.5pg/ml). Thus, the combination of cell sheets and magnetic technologies hold promise for the development of living tendon substitutes. Acknowledgement to ERC-COG MagTendon772817, H2020 Achilles 810850, FCT - 2020.01157.CEECIND

Abstract. Patellofemoral Arthroplasty (PFA) is an alternative to TKA for patellofemoral osteoarthritis that preserves tibiofemoral compartments. It is unknown how implant positioning affects biomechanics, especially regarding the patella. This study analysed biomechanical effects of femoral and patellar component position, hypothesising femoral positioning is more important. Nine cadaveric knees were studied using a repeated-measures protocol. Knees were tested intact, then after PFA implanted in various positions: neutral (as-planned), patellar over/understuffing (±2mm), patellar tilt, patellar flexion, femoral rotation, and femoral tilt (all ±6°). Arthroplasties were implemented with CT-designed patient-specific instrumentation. Anterior femoral cuts referenced Whiteside's line and all femoral positions ensured smooth condyle-to-component transition. Knee extension moments, medial patellofemoral ligament (MPFL) length-change, and tibiofemoral and patellofemoral kinematics were measured under physiological muscle loading. Data were analysed with one-dimensional statistical parametric mapping (Bonferroni-Holm corrected). PFA changed knee function, altering extension moments (p<0.001) and patellofemoral kinematics (p<0.05), but not tibiofemoral kinematics. Patellar component positioning affected patellofemoral kinematics: over/understuffing influenced patellar anterior translation and the patellar tendon moment arm (p<0.001). Medially tilted patellar cuts produced lateral patellar tilt (p<0.001) and vice versa. A similar inverse effect occurred with extended/flexed patellar cuts, causing patellar flexion and extension (p<0.001), respectively. Of all variants, only extending the patellar cut produced near-native extension moments throughout. Conversely, the only femoral effect was MPFL length change between medially/laterally rotated components. PFA can restore native knee biomechanics. Provided anterior femoral cuts are controlled and smooth condyle-to-component transition assured, patellar position affects biomechanics more than femoral, contradicting the hypothesis

A key component to the success of total knee replacement is the health and integrity of the extensor mechanism. While there are issues related to the patella, such as fracture, dislocation, subluxation, clunk due to peripatellar fibrosis and anterior knee pain, the overall integrity of the extensor mechanism is of tantamount importance in providing an excellent functional outcome. During total knee replacement it is of utmost importance to preserve the anatomic insertion of the patellar tendon on the tibial tubercle. However, after total knee replacement, a fall or extreme osteoporosis of the patella may cause a rupture of the patellar tendon, distally or proximally, and possibly the quadriceps tendon off of the proximal pole of the patella. Simple repairs of the patellar tendon avulsion may involve use of the semitendonosis and gracilis tendons along with primary repair of the tendon. Usually, patella infera develops after such a repair affecting overall strength and function. For severe disruptions of the extensor mechanism that are accompanied by a significant extensor lag, autologous tissue repair may not be possible. Thus, there are three techniques for reconstruction of this difficult problem: Extensor mechanism allograft with bone-patellar tendon-patella-quadriceps tendon, extensor mechanism allograft with os calcis-Achilles tendon construct and Marlex-mesh reconstruction for patellar tendon avulsion. The key to success of extensor mechanism allograft is proper tensioning of the allograft at full extensor and immobilisation for 6 weeks. Rosenberg's early experience showed that the allograft works best placed at maximum tension in extension. Rubash has described the use of the os calsis-Achilles tendon which does not utilise a patellar substitute. Hansen has recently described excellent results with the use of Marlex mesh to act as a structural reinforcement to the patellar tendon when it is avulsed

We reviewed the records of 107 consecutive patients who had undergone surgery for disruption of the knee extensor mechanism to test whether an association existed between rupture of the quadriceps tendon and the presence of a patellar spur. The available standard pre-operative lateral radiographs were examined to see if a patellar spur was an indicator for rupture of the quadriceps tendon in this group of patients. Of the 107 patients, 12 underwent repair of a ruptured patellar tendon, 59 had an open reduction and internal fixation of a patellar fracture and 36 repair of a ruptured quadriceps tendon. In the 88 available lateral radiographs, patellar spurs were present significantly more commonly (p < 0.0005) in patients operated on for rupture of the quadriceps tendon (79%) than in patients with rupture of the patellar tendon (27%) or fracture of the patella (15%). In patients presenting with failure of the extensor mechanism of the knee in the presence of a patellar spur, rupture of the quadriceps tendon should be considered as a possible diagnosis

We developed an in vivo model of the attachment of a patellar tendon to a metal implant to simulate the reconstruction of an extensor mechanism after replacement of the proximal tibia. In 24 ewes, the patellar tendon was attached to a hydroxyapatite (HA)-coated titanium prosthesis. In 12, the interface was augmented with autograft containing cancellous bone and marrow. In the remaining ewes, the interface was not grafted. Kinematic gait analysis showed nearly normal function of the joint by 12 weeks. Force-plate assessment showed a significant increase in functional weight-bearing in the grafted animals (p = 0.043). The tendon-implant interface showed that without graft, encapsulation of fibrous tissue occurred. With autograft, a developing tendon-bone-HA-implant interface was observed at six weeks and by 12 weeks a layered tendon-fibrocartilage-bone interface was seen which was similar to a direct-type enthesis. With stable mechanical fixation, an appropriate bioactive surface and biological augmentation the development of a functional tendon-implant interface can be achieved

Introduction: Functional outcome following proximal tibial replacement can be impaired by extensor mechanism inefficiency. Current methods used to re-attach the patellar tendon result in varied levels of extensor function. Successful attachment of the patellar tendon requires initial mechanical stability and long-term biological fixation. We have employed a prosthesis, to model patellar tendon re-attachment, to test the hypothesis that biological augmentation of an implant which can provide sufficient mechanical integrity will allow a tendon-implant interface to develop that is similar in function and morphology to a normal tendon-bone interface. Methods: The right patellar tendon in 24 Skeletally mature Friesland ewes was transfixed between the interlocking spikes of a hydroxyapatite-coated, customized tendon clamp to simulate patellar tendon re-attachment to a proximal tibial replacement. In 12 animals (Autograft group) the clamp attachment was augmented with autologous cancellous bone and marrow graft harvested from the ipsilateral iliac crest at the time of surgery, whilst the remaining animals (HA group) served as un-supplemented controls. Functional outcome was assessed using force plate measurements and two-dimensional optical kinematic gait analysis. Animals were euthanised at 6 and 12 weeks. The specimens were harvested, processed for histology and examined using light microscopy. Results: The clamp device provided sufficient mechanical fixation of the patellar tendon to allow immediate weight bearing. Gait analysis showed that the range of movement of the stifle (knee) joint was not compromised by the surgical intervention at 6 or 12 weeks post-operation. An extensor lag observed at 6 weeks in both the Autograft and HA group was seen to fully recover by 12 weeks post-operation. There was a significant increase in functional weight bearing through the operated limb of the Autograft group animals between 6 and 12 weeks, which was not observed in the HA group. The tendon-implant interface in the HA group animals showed a fibrous tissue encapsulation of the HA coated surface, with collagen fibrils running parallel to the implant surface. In the Autograft group at 6 weeks post-operation a soft tissue – bone – HA interface had developed, similar in morphology to that of an indirect-type enthesis. Perpendicular orientated Sharpey’s-like fibres were observed spanning the region between the tendon and the HA coated implant and the bone graft material was seen to be undergoing active remodelling. By 12 weeks post-operation the interface was layered with regions of fibrocartilage clearly visible, more closely resembling the morphology of a direct-type enthesis. Discussion: The clamp device provided sufficient mechanical fixation of the patellar tendon to allow immediate use the operated limb. The incorporation of a bio-active implant coating and biological augmentation encouraged a neo-enthesis to develop with near normal functional properties, and morphology similar to that of a normal patellar tendon-bone direct-type enthesis

We assessed the reproducibility and accuracy of four ratios used to measure patellar height, namely the Blackburne-Peel, Caton-Deschamps, Insall-Salvati and modified Insall-Salvati, before and after total knee arthroplasty. The patellar height was measured, by means of the four ratios, on the pre- and post-operative lateral radiographs of 44 patients (45 knees) who had undergone total knee arthroplasty. Two independent observers measured the films sequentially, in identical conditions, totalling 720 measurements per observer. Statistical analysis, comparing both observers and ratios, was carried out using the intraclass correlation coefficient. Before operation there was greater interobserver variation using either the Insall-Salvati or modified Insall-Salvati ratios than when using the Caton-Deschamps or Blackburne-Peel methods. This was because of difficulty in identifying the insertion of the patellar tendon. Before operation, there was a minimal difference in reliability between these methods. After operation the interobserver difference was greatly reduced using both the Caton-Deschamps and Blackburne-Peel methods, which use the prosthetic joint line, compared with the Insall-Salvati and modified Insall-Salvati, which reference from the insertion of the patellar tendon. The theoretical advantage of using the Insall-Salvati and modified Insall-Salvati ratios in measuring true patellar height after total knee arthroplasty needs to be balanced against their significant interobserver variability and inferior reliability when compared with other ratios

Ruptures of the patellar and/or quadriceps tendon are rare injuries requiring immediate repair to re-establish knee extensor continuity and to allow early motion. Ultrasound is extensively used as a diagnostic tool before surgery on acute traumatic tears of the patellar tendon and quadriceps tendons. Our aim was to re-evaluate the value/role of sonography in diagnosing quadriceps and patellar tendon rupture and in differentiating partial from complete tears. To correlate the intra operative findings with the ultrasound report. A retrospective review of 32 consecutive patients who had a surgical intervention for suspected acute quadriceps and patellar tendon rupture over the last 3 years. Intra-operative findings, clinical, x-ray, ultrasound and MRI reports were correlated. Seventeen patients had a suspected patellar tendon rupture on clinical examination and 15 patients had suspected quadriceps tendon rupture. Diagnosis was confirmed by clinical examination and x-rays alone in 9 patients, with additional ultrasound in 18 patients and with MRI scan in 5 patients. There were 6 false positives out of 18 [33.3%] in the ultrasound proven group and 1 false positive out of 9 [11.1%] in the clinical examination and x-ray only group. MRI was 100% accurate [n=5]. This is a small, but important study. Ultrasound offers a low degree of sensitivity and specificity in diagnosing acute quadriceps and patellar tendon ruptures. As a result, patients are being exposed to the risks of surgery unnecessarily. We recommend MRI scan as a first line of investigation in patients where the diagnosis is clinically ambiguous. Ultrasound assessment should not be relied upon in when making the decision to operate

Purpose of the study: Variations in patellar height in relation to the trochlea and the joint line can be a cause of pain and instability and limit the range of knee flexion. The Caton and Deschamps index (CDI) was described and validated in a cohort of adult subjects. The purpose of this work was to validate this index and set the reference values in a paediatric population. Material and methods: Lateral view of the knee were obtained in 300 patients who consulted for minor trauma without ligament or bone injury. Thirty patients, aged 6 to 15 years, were included in each age group (1-year groups). All radiographs were qualified as normal by the radiologist. Two series of measures were made in random order and at an interval of 8 days by two independent observers. The patellar height and the length of the patellar tendon were measured with computer assistance. The interob-server and intraobserver variabilities were determined. Results: The mean patellar height was 33.39±7.40 mm. The mean length of the patellar tendon was 34.57±67.36 mm. The mean CDI was 1.06±0.21. There was not significant correlation between patient age, height of the patella and length of the patellar tendon. Thus the height of the patella and the length of the patellar tendon increased with age while the CDI was statistically lower in older patients. The height of the patella was identical in the two genders while the patellar tendon was statistically longer in boys. The CDI was statistically higher in boys. Interobserver and intraobserver agreement was excellent. Discussion: CDI is a simple and reproducible measurement in adults and in children and adolescents. During growth, it is an alternative to the Insall index which has limited reproducibility and the Koshino index which is difficult to use in routine clinical situations. We found a correlation between CDI and children’s age, related to progressive ossification of the patella. Conclusion: The CDI is a tool which can be used in routine practice to study patellofemoral problems in the paediatric population as long as the physiological values are weighted by age

Background. Use of a robotic tool to perform surgery introduces a risk of unexpected soft tissue damage due to the uncommon tactile feedback for the surgeon. Early experience with robotics in total hip and knee replacement surgery reported having to abort the procedure in 18–34 percent of cases due to inability to complete preoperative planning, hardware and soft tissue issues, registration issues, as well as concerns over actual and potential soft tissue damage. These can result in significant morbidity to the patient, negating all the desired advantages of precision and reproducibility with robotic assisted surgery. The risk of soft tissue damage can be mitigated by haptic software prohibiting the cutting tip from striking vital soft tissues and by the surgeon making sure there is a clear workspace path for the cutting tool. This robotic total knee system with a semi-active haptic guided technique was approved by the FDA on 8/5/2015 and commercialized in August of 2016. Two year clinical results have not been reported to date. Objective. To review an initial and consecutive series of robotic total knee arthroplasties for safety in regard to avoidance of known or delayed soft tissue injuries and the necessity to abort the using the robot to complete the procedure. Report the clinical outcomes with robotic total knee replacement at or beyond two years to demonstrate no delayed effect on expected outcome. Methods. The initial consecutive series of 65 Triathlon. TM. total knee replacements using a semi-active haptic guided system that were performed after commercialization that would be eligible for two year follow-up were reviewed. Pre-operative planning utilizing CT determined the implant placement and boundaries and thus the limit of excursion from any part of the end effector saw tip. Self-retaining retractors were also utilized. Operative reports, 2, 6, and 12 week, and yearly follow-up visit reports were reviewed for any evidence of inadvertent injury to the medial collateral ligament, patellar tendon, or a neurovascular structure from the cutting tool. Operative notes were also reviewed to determine if the robotic procedure was partially or completely aborted due to any issue. Knee Society Knee Scores (KS-KS) and Functional Scores (KS-FS) were recorded from pre-operative and yearly. Any complications were recorded. Results. 40 cases had two year follow-up. The average follow-up for this series was 1.51 years. No cases were unable to be completed robotically. No case had evidence for acute or delayed injury to the medial collateral ligament, patellar tendon, or neurovascular structure. The only complication was a revision total knee for tibial component loosening after a fall induced periprosthetic tibial fracture. Average pre-operative KS-KS and KS-FS improved from 46.9 and 52.1 to 99.2 and 88.6 at one year follow-up, 100.5 and 86.9 at two year follow-up. Conclusions. A semi-active haptic guided robotic system is a safe and reliable method to perform total knee replacement surgery. This series of initial robotic arm assisted surgery had no intraoperative or delayed soft tissue injuries. Preliminary short-term outcomes at up to two years show excellent outcomes

Background. Jumper's knee is the result of violent and repeated contractions of quadriceps muscle caused by rapid acceleration and deceleration, jumping and kicking that load on patellar tendon stressing its mechanical resistance. The porpose of this retrospective study is to analyze the results, after the debridment of the patellar tendon and the patellar apex abrasion performed by arthroscopy, at a mean follow-up of seven years. Methods. From 1996 to 2006, sixty-four patients (seventy-three knees) affected by jumper's knee underwent surgical tretment after failure of nonoperative treatment. All knees were operated on by the same surgeon using the same surgical technique: arthroscopic debridement of the articular face of patellar tendon and arthroscopic abrasion of patellar apex. Pre-operative and post-operative evaluation was made according to IKDC score, Lysholm Knee Scale and VISA-P score. Results. The pre-operative subjective IKDC score was 52,96. This score significantly increased to 94,72 at 12 months post-operation, and has remained nearly constant at 10 years of follow-up. The mean pre-operative Lysholm Knee Scale was 51,57 and significantly increased to 86,48 at 12 months post-operation again remaining nearly constant at 10 years of follow-up. The score according to VISA-P which was pre-operatively 35,32 increased to 69,80 at 12 months post-operation and was 69,35 at 10 years of follow-up. Nineteen of the twenty-seven patients who were involved in competitive sport continued it at the same level and twenty-four were symptoms-free. Conclusions. For these satisfactory results, for the low aggressivity of this surgery, for the short recovery time and the faster return to sport we think that the debridment of the patellar tendon and the patellar apex abrasion performed by arthroscopy is the technique to prefer for surgical treatment of Jumper's Knee

Aim. Quadrupled hamstring anterior cruciate ligament plasties (4xHp) have been described as having a higher risk of infection than bone patellar tendon bone plasties (BPTBp). There are 2 theories that might explain this phenomenon. One is the presence of sutures in a 4xHp that could act as a foreign body, The other is the more complex preparation of a 4xHp that might lead to higher contamination rates during the process. The objective of the present study was to evaluate the formation of biofilm in these plasties and to compare it between a 4xHp and a BPTBp. The hypothesis was that the presence of sutures in 4xHp would increase the amount of biofilm present in them in comparison to BPTBp. Method. A descriptive in vitro study was conducted. One 4xHp and one BPTBp were prepared. They were subsequently divided into 8 fragments. Three of them were reserved for negative control, and the rest were contaminated with a strain of S. Epidermidis (ATCC 35984) 10–5. Finally, a quantitative analysis was carried out by means of microcalorimetry and sonication with plating. Additionally, a qualitative analysis was carried out by means of electron microscopy. Results. In isothermal microcalorimetry, both contaminated plasties showed the same growth dynamics with a population peak (200uW) at 8h. No significant differences were found between the bacterial growth profiles of 4xHp and BPTBp. The product of sonication was plated and the number of colony forming units per milliliter (CFU/ml) was counted at 24 hours. No significant differences were detected between the 4×Hp (mean +/− sem = 3,5×107 +/− 3450000) and the BPTBp (4,6 ×107 +/− 1,455e+7). With a p value of 0.6667, there were no differences of significance (Mann-Whitney test). In the samples analyzed with electron microscopy, no specific biofilm growth pattern was identified upon comparing BPTBp with 4xHp. Conclusions. There were no significant differences at either the quantitative or qualitative level when comparing bacterial growth in BPTBp and 4xHp. Therefore, the presence of sutures in 4xHp cannot be established as a predisposing factor to higher infection rates. These findings may be justified in the sense that the plasties themselves already behave like foreign bodies. Therefore, the presence of sutures does not increase the possibility of biofilm forming on their surface

Introduction. Patellar crepitus and clunk are tendofemoral-related complications predominantly associated with posterior-stabilizing (PS) total knee arthroplasty (TKA) designs [1]. Contact between the quadriceps tendon and the femoral component can cause irritation, pain, and catching of soft-tissue within the intercondylar notch (ICN). While the incidence of tendofemoral-related pathologies has been documented for some primary TKA designs, literature describing revision TKA is sparse. Revision components require a larger boss resection to accommodate a constrained post-cam and stem/sleeve attachments, which elevates the entrance to the ICN, potentially increasing the risk of crepitus. The objective of this study was to evaluate tendofemoral contact in primary and revision TKA designs, including designs susceptible to crepitus, and newer designs which aim to address design features associated with crepitus. Methods. Six PS TKA designs were evaluated during deep knee bend using a computational model of the Kansas knee simulator (Figure 1). Prior work has demonstrated that tendofemoral contact predictions from this model can differentiate between TKA patients with patellar crepitus and matched controls [2]. Incidence of crepitus of up to 14% has been reported in Insall-Burstein® II and PFC® Sigma® designs [3]. These designs, in addition to PFC® Sigma® TC3 (revision component), were included in the analyses. Primary and revision components of newer generation designs (NexGen®, Attune® and Attune® Revision) were also included. Designs were evaluated in a patient model with normal Insall-Salvati ratio and a modified model with patellar tendon length reduced by two standard deviations (13mm) to assess worst-case patient anatomy. Results. During simulations with normal patellar tendon length, only PFC® Sigma® and PFC® Sigma® TC3 showed tendofemoral contact within the trochlea, and no design showed contact at the transition to the ICN (Figure 2). In simulations with patella baja, Insall-Burstein® II, PFC® Sigma®, and PFC® Sigma® TC3, demonstrated tendofemoral contact across the trochlea at the transition into the notch. In contrast, NexGen®, Attune® and Attune® Revision showed tendon contact for approximately half the width of the transition to the notch (Figure 3). PFC® Sigma® and Attune® demonstrated very similar tendofemoral contact to their equivalent revision components, although the shorter trochlear groove of Attune® Revision marginally increased contact at the transition. Discussion. Insall-Burstein® II, PFC® Sigma®, and PFC® Sigma® TC3 designs showed full contact with the quadriceps tendon at the anterior border of the ICN when combined with a short patellar tendon. NexGen®, Attune® and Attune® Revision had a more gradual transition between the trochlea and the notch, which resulted in less exposure to tendon contact. Even with the shorter trochlear groove required for revision components, Attune® Revision showed minimal difference in tendofemoral contact when compared with Attune®. There appears to be distinct benefit in a femoral design which reduces tendofemoral contact at the transition to the ICN; this may be of particular importance for patients with patella baja

Introduction. Patellar resurfacing affects patellofemoral (PF) kinematics, contact mechanics, and loading on the patellar bone. Patients with total knee arthroplasty (TKA) often exhibit adaptations in movement patterns that may be linked to quadriceps deficiency and the mechanics of the reconstructed knee [1]. Previous comparisons of PF kinematics between dome and anatomic resurfacing have revealed differences in patellar sagittal plane flexion [2], but further investigation of PF joint mechanics is required to understand how these differences influence performance. The purpose of this study was to compare PF mechanics between medialized dome and medialized anatomic implants using subject-specific computational models. Methods. A high-speed stereo radiography (HSSR) system was used to capture 3D sub-mm measurement of bone and implant motion [3]. HSSR images were collected for 10 TKA patients with Attune® (DePuy Synthes, Warsaw, IN) posterior-stabilized, rotating-platform components, 5 with medialized dome and 5 with medialized anatomic patellar components (3M/7F, 62.5±6.6 years, 2.2±0.6 years post-surgery, BMI: 26.2±3.5 kg/m. 2. ), performing two activities of daily living: knee extension and lunge (Figure 1). Relative motions were tracked using Autoscoper (Brown University, Providence, RI) for implant geometries obtained from the manufacturer. A statistical shape model was used to predict the patella and track motions [4]. Subject-specific finite element models of the experiment were developed for all subjects and activities [5]. The model included implant components, patella, quadriceps, patellar tendon, and medial and lateral PF ligaments (Figure 2a). While tibiofemoral kinematics were prescribed based on experimental data, the PF joint was unconstrained. A constant 1000N quadriceps load was distributed among four muscle groups. Soft tissue attachments and pre-strain in PF ligaments were calibrated to match experimental kinematics [5]. Model outputs included PF kinematics, patellar and contact force ratios, patellar tendon angle, and moment arm. Results and Discussion. Load-bearing activities presented larger variations in PF kinematics and mechanics between dome and anatomic subjects. Consistent with previous findings [2], patients with medialized anatomic geometry achieved greater patellar flexion than those with the medialized dome during lunge (16±3° from 40–100° knee flexion), and demonstrated PF kinematics closer to that of the natural knee (Figure 2b) [6]. Dome subjects experienced greater PF internal-external range-of-motion compared to the anatomic subjects (8±5°). Model PF kinematics closely replicated the experiment with average root-mean-square differences of flexion-extension<5°, internal-external<3°, and medial-lateral<2 mm. Dome subjects demonstrated larger contact force ratios than anatomic, but presented smaller patellar force ratios in deep flexion (–60°). Smaller PF flexion angles in dome implants likely influenced the increase in contact force ratio, which may increase implant forces and decrease quadriceps efficiency. In contrast, the flexed position of the anatomic design distributed load to the patellar tendon at deeper flexion angles, which may improve extensor function (Figure 3). The current modeling framework can inform implant designers on the impact of articular geometry on quadriceps efficiency

The conservative treatment of ACL lesions in the adolescent is unfavourable in the long term risking precocious joint deterioration. Nevertheless, literature does not agree on the timing and on the best type of surgery in this age group. The results of ACL repairs with the open technique are evaluated negatively. We present a retrospective evaluation of a case history of adolescents surgically treated with ACL reconstruction with patellar tendon or with arthroscopic reinsertion of the ACL in the case of proximal lesions and of good quality ligamentous tissue. Materials and methods: From 1990 to 2006, adolescents under 18 were surgically treated for instability as a consequence of ACL rupture. 75 of these were evaluated retrospectively and divided into two groups: 59 cases, mean age 16 years (13–17), 28 males and 31 females were treated with patellar tendon, Group A. 16 cases, mean age 14 years (11–17), 8 males and 8 females, were treated with arthroscopic repair of the ACL (mean time between lesion and surgery 24 days, 2–200, Group B. Mean follow up 120 months (18–204). The evaluation of the results was carried out using the IKDC 2000 score. In all cases a clinical, radiographic and MRI evaluation was performed. Results: Group A: 50 A, 5 B, 4 C. Group B: 14 A, 1 B, 1 C. Subjective IKDC: Group A mean 97 (80–100). Group B mean 99 (81–100). Conclusions: The high percentage of good or excellent results (93%) confirms the possibility of a complete functional recovery, after the lesion of the ACL in the adolescent, with surgery. The use of the patellar tendon for the repair does not result as having compromised the functionality of the extensor apparatus. Excellent results are possible both with patellar tendon and with ACL reinsertion in the case of proximal lesions and of a good quality of the ligament. Reinsertion with the arthroscopic technique results efficacious in a high percentage of subjects. Above all, it is indicated when the young biological age of the patient could mean postponing reconstructive surgery with the risk of secondary lesions and of successive unsatisfactory results

Background. Use of a robotic tool to perform surgery introduces a risk of unexpected soft tissue damage due to the lack of tactile feedback for the surgeon. Early experience with robotics in total hip and knee replacement surgery reported having to abort the procedure in 18–34 percent of cases due to inability to complete preoperative planning, hardware and soft tissue issues, registration issues, as well as concerns over actual and potential soft tissue damage. These damages to the soft tissues resulted in significant morbidity to the patient, negating all the desired advantages of precision and reproducibility with robotic assisted surgery. The risk of soft tissue damage can be mitigated by haptic software prohibiting the cutting tip from striking vital soft tissues and by the surgeon making sure there is a clear workspace path for the cutting tool. This robotic total knee system with a semi-active haptic guided technique was approved by the FDA on 8/5/2015 and commercialized in August of 2016. One year clinical results have not been reported to date. Objective. To review an initial and consecutive series of robotic total knee arthroplasties for safety in regard to avoidance of known or delayed soft tissue injuries and the necessity to abort the robotic assisted procedure and resort to the use of conventional implantation. Report the clinical outcomes with robotic total knee replacement at or beyond one year to demonstrate satisfactory to excellent performance. Methods. The initial consecutive series of 100 robotic total knee replacements using a semi-active haptic guided system including 34 from the initial IDE series in 2014 and those performed after commercial approval beginning in 2016 were reviewed. Pre- operative planning utilizing CT determined the implant placement and boundaries and thus the limit of excursion from any part of the end effector saw tip. Self-retaining retractors were also utilized. Operative reports, 2, 6, and 12 week, and yearly follow-up visit reports were reviewed for any evidence of inadvertent injury to the medial collateral ligament, patellar tendon, or a neurovascular structure from the cutting tool. Operative notes were also reviewed to determine if the robotic procedure was partially or completely aborted due to any issue. Knee Society and Functional scores were recorded from pre-operative and yearly. Results. No cases were unable to be completed robotically. No case had evidence for acute or delayed injury to the medial collateral ligament, patellar tendon, or neurovascular structure. The average follow-up for this series was 1.54 years. Average pre- operative Knee Society and Functional Scores improved from 44.7 and 50 to 98.1 and 87.8 at one year follow-up, 93.8 and 83.1 at two year follow-up, 98.5 and 87.7 at three year follow-up, and 99 and 85 at four year follow-up. Conclusions. A semi-active haptic guided robotic system is a safe and reliable method to perform total knee replacement surgery. Preliminary short-term outcomes data shows excellent clinical and functional results

The purpose of this study was to analyse the effects of two different biomechanical configurations on the tensile properties of equine patellar tendons. The study looked at a comparison of straight untwisted patellar tendons and double stranded, twisted specimens. The aim was to attempt a more anatomical Anterior Cruciate Ligament configuration when performing reconstruction using the patellar tendon. Thirty four specimens were harvested and each sample group consisted of a pair of equine ligaments taken from the same animal. The first of the pair served as an ‘untwisted, straight ligament’ control group and the second as the ‘twisted, double stranded test group’. The ligament dimensions were measured for each specimen and the specimen was mounted on an Instron Series 4411© tensile testing machine and tensile load was applied until failure. Results showed a clearly statistically significant reduction in the tensile properties (p< 0.005) of the twisted double stranded specimens which was against our original hypothesis. The results indicated that the twisted double stranded ligaments had only 65% of the tensile strength of their untwisted counterparts. Similar reductions were demonstrated when calculating energy to yield point and load at zero point yield stress. The results also demonstrated a significant reduction in the stiffness (Young’s Modulus) between the two test configurations. The application of a double stranded twist to the patellar tendon confers no advantage in terms of tensile property of the ligament. In fact the application of such a model may cause significant reduction in strength and stiffness of the construct which may lead to early failure of the ACL patellar tendon autograft

Introduction: knee revision in absence of Extensor Mechanism has been always a challenging problem in Orthopaedics. Many authors are in favour to abandone any endoprosthetic substitution in front of such a situation. We think osteotendinous allografts, in this particular case whole Extensor Mechanism allografts, could play an essential role before any Knee Arthrodesis. Material and Method: From 1999 up to 2004 11 patients (4 male, 7 female) (mean age 72, range 68 to 86) underwent to a whole Extensor Mechanism allografting procedure. Mean follow up was 2.7 years (1 to 5 years). In the first four cases a whole Extensor Mechanism allograft was implanted, while the next seven cases the allograft was reinforced by means of a Leeds-Keio Dacron band. Results: There was no infections in this serie. The mean obtained R.O.M. in the first three months was – 5 of active extension (range 0 to −15) and 95 active flexion (range 80 – 110). However 3 from the 4 former operated cases had a progressive loss of active extension up to −25 (range −20 to −35) at 18 months, that did not increase after this period. Ultrasonic exams showed a lengthening of the patellar tendon in these cases. None of these 3 patients wished to undergo to a patellar tendon reinforcement. On the other hand those later cases, where patellar tendon was reinforced did not show any change over the time (at 18 months mean active extension was maintained to −5 (range 0 to 15). Conclusions: Extensor mechanism allografts are very useful in difficult knee revisions with absence of extensor mechanism, so that knee arthrodesis is not the method of choice for these patients. However augmentation of patellar tendon is necessary to maintain with the years an active extension

We report an unusual case of knee disease where calcific tendonitis occurring in both quadriceps and patellar tendon simultaneously in the same knee. A 47 year old female presented to orthopaedics outpatient clinic with acute onset of swelling and knee pain with no history of trauma. She was found to have a moderate effusion of the knee joint with mild tenderness over the mid quadriceps tendon. Active flexion of the knee joint was painful with a range of motion between 0-90 degrees. She is otherwise healthy with no past medical history. Plain radiographs and Magnetic Resonance Imaging (MRI) Scan revealed calcification of both tendons. Calcific tendonitis is classically found in the supraspinatus tendon of the shoulder. In addition, it has been described in other areas of the body such as the wrist, thigh, hip, knee and ankle. This condition usually occurs in the quadriceps or patellar tendons separately and rarely affecting both tendons in the same knee simultaneously. The patients condition improved significantly with physiotherapy, anti-inflammatory medications and ultrasound therapy. Calcific tendinitis of both quadriceps and patellar tendon is a very rare cause of knee pain. Most of the time it is treated conservatively with non-steroidal anti-inflammatory drugs and ultrasound therapy and some times steroid injection. However; patient may require surgical intervention especially in refractory cases to resolve the condition

Introduction: Despite advances in limb-sparing techniques, the proximal tibia remains a difficult area in which to perform a wide resection of extensive bone tumors due to the intimate relationship to the nerves and blood vessels, inadequate soft-tissue coverage, and the need to reconstruct the extensor mechanism. The current long-term follow-up study, based on the experience with 55 patients who underwent proximal tibia endoprosthetic reconstruction emphasizes reconstruction of the extensor mechanism. Materials and Methods: Between 1980 and 1997, 55 patients underwent proximal tibia resection with endoprosthetic reconstruction. There were 34 males and 21 females whose age ranged from 8 to 56 years (median, 27 years. Diagnoses were: primary bone sarcomas – 48, benign aggressive lesions – 6, and failure of previous osteoarticular allograft reconstruction – 1. Intra-articular resection with en bloc removal of the tibial tuberosity was performed in all cases. Endoprosthetic reconstruction was performed with 39 modular, 16 custom-made prostheses. Reconstruction of the extensor mechanism included reattachment of the patellar tendon to the prosthesis with a Dacron tape and reinforcement with a gastrocnemius flap and bone grafting of the patellar tendon-prosthesis interface. Rehabilitation emphasized prolonged immobilization of knee joint in full extension. Results: All patients were followed for a minimum of 2 years (range 24–235 months, median – 75.5 months). Full extension to extension lag of 20° was achieved in 44 patients (78%), extension lag of 20° to 30° was found in 10 patients (19%), and extension lag of 40° was found in 1 patient (3%). Eight patients required an additional procedure which involved reinforcement of the patellar tendon with either combined quadriceps tendon and Goretex graft construct (seven patients) or simple plication of the tendon (one patient). Seven of these patients gained an extension lag of less than 20°. Overall, function was estimated to be good to excellent in 48 patients, fair in 6, and poor in one patient. Discussion: Extension lag of up to 20° is considered compatible with activities of daily living. Emphasis on reattachment of the patellar tendon to the prosthesis and its reinforcement with a gastrocnemius flap and bone graft achieved that goal in the majority of the patients. Secondary reinforcement of the patellar tendon is recommended for extension lag of more than 20°

Introduction: Bunnell suture technique is effective for tendon repair. A modification of the classic suture technique could increase ultimate failure point (UFP) on the suture-tendon site. The purpose of this study is to evaluate UFP of regular and modified Bunnell suture techniques on in vitro porcine patellar tendons. Methods: Porcine patellar tendon samples (N=24) were used for this study, separating them in 2 groups: Group A: classic Bunnell suture on the tendon (N=12). Group B: two perpendicular Bunnell sutures at 90° between them on the tendon (N=12). After suturing the samples, axial traction until failure on the tendon-suture site was applied on samples of both groups documenting UFP with a tension sensor device. UFP was measured and described in Newtons for all samples. Statistics: Non parametric Mann-Whitney test for independent variables was used to analyze outcomes. Results: The UFP for group A was 224 ± 38,9 N. The UFP for group B was 307 ± 19,9 N. We found statistical differences among groups (p=0,00006). Discussion: In this study we analyzed the UFP of classic Bunnell suture technique vs. a modification adding a second Bunnell suture perpendicular to the classic technique. The purpose of this modification is to increase the contact area between the suture and the tendon, reaching a stronger disposition at suture-tendon site. This has been documented in the UFP values obtained. Conclusion: Adding a perpendicular Bunnell suture run in porcine ex vivo patellar tendons increases UFP in tendon repair at tendon – suture site

Introduction and Objective. Anterior cruciate ligament reconstruction (ACLR) with tendon autografts is the “gold standard” technique for surgical treatment of ACL injuries. Common tendon graft choices include patellar tendon (PT), semitendinosus/gracilis “hamstring” tendon (HT), or quadriceps tendon (QT). Healing of the graft after ACLR may be affected by graft type since the tissue is subjected to mechanical stresses during post-operative rehabilitation that play important roles in graft integration, remodeling and maturation. Abnormal mechanical loading can result in high inflammatory and degradative processes and altered extracellular matrix (ECM) synthesis and remodeling, potentially modifying tissue structure, composition, and function. Because of the importance of load and ligamentization for tendon autografts, this study was designed to compare the differential inflammatory and degradative metabolic responses to loading by three tendon types commonly used for autograft ACL reconstruction. Materials and Methods. With IRB approval (IRB # 2009879) and informed patient consent, portions of 9 QT, 7 PT and 6 HT were recovered at the time of standard of care ACLR surgeries. Tissues were minced and digested in 0.2 mg/ml collagenase solution for two hours and were then cultured in 10% FBS at 5% CO. 2. , 37°C, and 95% humidity. Once confluent, cells were plated in Collagen Type I-coated BioFlex® plates (1 × 10. 5. cells/well) and cultured for 2 days prior to the application of strain. Then, media was changed to supplemented DMEM with 2% FBS for the application of strain. Fibroblasts were subjected to continuous mechanical stimulation (2-s strain and 10-s relaxation at a 0.5 Hz frequency) at three different elongation strains (mechanical stress deprivation-0%, physiologic strain-4%, and supraphysiological strain-10%). 9. for 6 days using the Flexcell FX-4000T strain system. Media was tested for inflammatory biomarkers (PGE2, IL-8, Gro-α, and MCP-1) and degradation biomarkers (GAG content, MMP-1, MMP-2, MMP-3, TIMP-1, and TIMP-2). Significant (p<0.05) difference between graft sources were assessed with Kruskal-Wallis test and post-hoc analysis. Results are reported as median± interquartile range (IQR). Results. Differences in Inflammation-Related Biomarker Production (Figure 1): The production of PGE2 was significantly lower by HT fibroblasts compared to both QT and PT fibroblasts at all timepoints and strain levels. The production of Gro-α was significantly lower by HT fibroblasts compared to QT at all time points and strain levels, and significantly lower than PT on day 3 at 0% strain, and all strain levels on day 6. The production of IL-8 by PT fibroblasts was significantly lower than QT and HT fibroblast on day 3 at 10% strain. Differences in Degradation-Related Biomarker Production (Figure 2): The production of GAG by HT fibroblasts was significantly higher compared to both QT and PT fibroblasts on day 6 at 0% strain. The production of MMP-1 by the QT fibroblasts was significantly higher compared to HT fibroblasts on day 3 of culture at all strain levels, and in the 0% and 10% strain levels on day 6 of culture. The production of MMP-1 by the QT fibroblasts was significantly higher compared to PT fibroblasts at in the 0% and 4% strain groups on day 3 of culture. The production of TIMP-1 by the HT fibroblasts was significantly lower compared to PT fibroblasts on day 3 of culture. Conclusions. The results of this study identify potentially clinically relevant difference in the metabolic responses of tendon graft fibroblasts to strain, suggesting a lower inflammatory response by hamstring tendon fibroblasts and higher degradative response by quadriceps tendon fibroblasts. These responses may influence ACL autograft healing as well as inflammatory mediators of pain in the knee after reconstruction, which may have implications regarding graft choice and design of postoperative rehabilitation protocols for optimizing outcomes for patients undergoing ACL reconstruction. For any figures or tables, please contact the authors directly