Three distal femoral axes have been described to aid in alignment of the femoral component; the Trans Epicondylar Axis (TEA), the Posterior Condylar Axis (PCA) and the Antero Posterior (AP) axis. Our aim was to identify if there was a reproducible relationship between the axes which would aid alignment of the femoral component. This is the first study compare all three distal femoral axes with each other using magnetic resonance imaging (MRI) in a Caucasian population. Our sample group represents real life patients awaiting total knee arthroplasty (TKA), as opposed non-arthritic or cadaveric knees.

We identified the relationship between these rotational axes by performing MRI scans on 89 patients awaiting TKA with patient-specific instrumentation. Measurements were taken by two observers.

Patients had a mean age of 62.5 years (range 32–91). 51 patients were female. The mean angle between the TEA and the AP axis was 92.78° with a standard deviation of 2.51° (range 88° – 99°). The mean angle between the AP axis and the PCA was 95.43° with a standard deviation of 2.75° (range 85° – 105°). The mean angle between the TEA and the PCA was 2.78° with a standard deviation of 1.91° (range 0° – 10°).

We conclude that while there is a reproducible relationship between the differing femoral axes, there is a significant range in the relationship between the femoral axes. This range may lead to greater inaccuracy than has previously been appreciated when defining the rotation of the femoral component. There is most variation between the PCA and the AP axis. The TEA's relationship with the PCA and AP appears important in defining rotation. Due to the well accepted difficulty in defining the TEA intra-operatively, there may be a role for patient-specific instrumentation in TKA surgery with pre-operative MRI.

Introduction and aims: Osteoarthritis (OA) of the knee is a widespread problem, yet there is little known about the kinematics of the osteoarthritic knee, and nothing about the tibio-femoral contact pattern. This study aimed to describe the role of tibio-femoral interface events in articular surface wear and degenerative change.

Method: Fourteen subjects with symptomatic OA in one knee, and no pain or injury in the contralateral knee were recruited. The tibio-femoral contact pattern was recorded for both knees, while performing a supine leg-press from 0 to 90 degrees flexion against a 150N load. Severity of osteoarthritis was measured by Kellgren Lawrence grade, bone mineral density (BMD) using Dual Energy X-ray Absorptiometry close to the subchondral bone, diagnostic MRI, and joint damage recorded at knee arthroplasty. Pain and disability was recorded using a WOMAC questionnaire.

Results: Severity of OA in the knees ranged from grade two to four (mode=4) in the symptomatic knee, and from zero to three (mode=0) in the contralateral knee. Contact in the lateral compartment of the knee was more anterior on the tibial plateau than healthy knees (p≤ 0.01), and this was associated with severity of OA (p≤ 0.01). Contact in the medial compartment was also more anterior on the tibial plateau, and this was associated with severity of OA. Abnormality in tibio-femoral contact patterns was associated with disability reported by the WOMAC score (r= 0.54). There was no significant difference in BMD between the OA and contralateral knees. However, the BMD was correlated with pain and physical function of the WOMAC score, that is, as function decreased, bone density increased in the arthritic compartment (r = 0.49 to 0.63; p≤ 0.01).

Conclusion: Severity of osteoarthritis was associated with loss of rollback normally coupled with flexion, especially in the lateral compartment. Consequently longitudinal rotation was lost. In severe osteoarthritis, ACL integrity did not affect the contact pattern. Kinematic abnormalities may explain loss of range of motion, and patterns of wear in osteoarthritic knees.

Three distal femoral axes have been described to aid in alignment of the femoral component; the Trans Epicondylar Axis (TEA), the Posterior Condylar Axis (PCA) and the Antero Posterior (AP) axis. Our aim was to identify if there was a reproducible relationship between the axes. Hopefully this will aid the surgeon to more accurately judge the rotation of the femoral cutting block by using the axes with the least variation. This is the first study compare all three distal femoral axes with each other using magnetic resonance imaging (MRI) in a Caucasian population awaiting total knee arthroplasty (TKA).

We identified the relationship between these axes by performing MRI scans on 89 patients awaiting TKA with patient-specific instrumentation. Measurements were taken by two observers.

Patients had a mean age of 62.5 years (range 32–91). 51 patients were female. The mean angle between the TEA and AP axis was 92.78°, standard deviation (SD) 2.51° (range 88°–99°). The mean angle between the AP axis and PCA was 95.43°, SD 2.75° (range 85°–105°). The mean angle between the TEA and PCA was 2.78°, SD 1.91° (range 0°–10°).

We conclude that while there is a reproducible relationship between the differing femoral axes, there is a significant range in the relationship between the femoral axes. This range may lead to greater inaccuracy than has previously been appreciated when defining the rotation of the femoral component. There is most variation between the PCA and the AP axis. Most systems have a cutting block with 3° of external rotation from the PCA and this would be parallel to the TEA in the majority, but not all, cases in this series. This data suggests that if the surgeon is to pick two axes to reference from, one should include the TEA.

Total ankle arthroplasty is used as a treatment for end stage arthritis of the ankle.

Surgical techniques highlight risk of injury to anterior neurovascular structures. No literature highlights injury risk to the posterior neurovascular structures in ankle replacement surgery. Current literature consists of cadaveric study in relation posterior ankle arthroscopy.

A retrospective review was done of ankle MRI's, performed by the senior author in his practice. Studies were included in the study where there was no pathology of the posterior ankle present. Axial, coronal and sagital T1 weighted films were reviewed and measurements of the posterior neurovascular structures and tendons were made in relation to the posterior tibia and medial malleolus in relation to planned tibial and talar cutting planes.

A total of seventy-eight MRI's were included in the study (ages ranged from 22 to 78 years). There were 40 females and 38 males. At the level of the tibial cut the tibial nerve and artery were between two to six millimeters from the posterior surface of the tibia. The flexor hallucis longus (FHL) is located in the midline between the medial malleolus and fibula, closely related to the posterior tibial surface. The flexor digitorum longus (FDL) tendon is located in the posterior medial corner of the ankle. There is a window approx ten millimeters wide between where the neurovascular structures lie between the FDL and FHL tendons. At the level of the talus cut the tibial nerve and artery were between five to 11 mm from the posterior body of the talus.

A similar window is present at this level where the neurovascular structures lie between the FDL and FHL tendons.

The neurovascular structures of the ankle are potentially at risk during the tibial and talar bone resection. They are most at risk with the transverse cut of the tibia. This may be decreased by preventing direct pressure over these structures during bone resection.

We report our experience of four initial cases of mosaicplasty using large plugs in four cases and subsequently fourteen cases using the OATS technique and large grafts.

The average size of the articular lesion was 1.7 sq cm with a range of 1–3 sq cm. The average number of grafts used was 2.3 with a range of 1.5. The average size was 9 mm with a range of 4–10 mm. Including a poor result due to infection, pain was only found in three patients on activity (17%). The Tegner score and the IKDC score improved significantly. The initial four cases of mosaicplasty resulted in two cases having donor site pain and crepitus which required a lateral release. Using the OATS technique reconstructing the donor site no further cases of pain and crepitus occurred.

On MRI imaging, the recipient site was congruous, intact and appeared functional and only one patient demonstrated protuberance of the articular cartilage (1mm). Recipient site marrow oedema, fluid accumulation or kissing tibial signals were not significant features. The donor site articular cartilage was congruent in 5 patients and homogeneously isointense in 6 out of 7 patients.

We have modified the technique and used osteochondral transplantation to treat isolated articular cartilage defects of 1–3 sq cm in area, using a mini open technique and multiple large grafts, avoiding graft impaction and with reconstruction of the donor site. This technique has resulted in an 89% success rate at an average of 2.5 years post operatively. Eighty three per cent of patients were able to return to recreational sports. MRI follow up has shown no cause for concern and demonstrates incorporation of all the grafts. The success reported in this study is higher than reported elsewhere but this may reflect the use of the modified technique.

Aims: We studied by means of a magnetic resonance imaging (MRI) protocol, the junction area between supratrochlear (ST) surface and the femoral trochlear groove (FT). The variations of this junction area are they correlated with the patientñs functional signs and with the patellar cartilage injuries?Method: We practised on 87 patients (64 patellar instability, 23 patellar pains) and 25 witnesses, an MRI: DESS and MPR sequences. The trochlear bump was studied in the sagittal plan according to the aspect of the junction area and in measuring itñs height. Results: The junction area was dismembered in 4 types according to its slope with the ST surface: ÒßatÒ, ÒroundÒ, ÒobliqueÒ and ÒsquareÒ. No atÒ typeÒßwas found in cases of FT dysplasia. The ÒobliqueÒ and ÒsquareÒ types were more frequent in cases of important projection of the FT (p< 0.0001). These two types were more frequently associated with the patellar cartilage injuries (p< 0.08). The trochlear projection was maximum (p< 0.0001) in FT dysplasia with spur, with a maximum effect in this case on patellar instability (p< 0.01) and also on patellar pain (p< 0.05). Conclusion: The junction area between the ST surface and the FT groove was dismembered in 4 types. A þrst ßat type without trochlear bump, and 3 types deþning a trochlear Òstep of stairÒ, round, square and oblique in order of growing gravity. The latter two were more common when patellar cartilage injuries existed.

Purpose: To assess if ACL reconstruction restores normal knee kinematics.

Methods: Tibiofemoral motion was assessed weight-bearing through the arc of flexion from 0 to 90° in ten patients who were at least 6 months following successful hamstring graft ACL reconstruction. Lachman’s test was also performed using dynamic MRI. Mid-medial and mid-lateral images were analysed in all positions to assess the tibiofemoral relationship.

Results: The laxity of the reconstructed knees was reduced to within normal limits. However the normal tibiofemoral relationship was not restored after ACL reconstruction with persistent anterior subluxation of the lateral tibial plateau throughout the arc of flexion 0–90°(p< 0.001).

Conclusion: Successful ACL reconstruction reduces joint laxity and improves stability but it does not restore normal knee kinematics.

AIM

Tibial component design has be been scrutinized in a number of studies in an attempt to improve tibial coverage in total knee arthroplasty. However, very few have controlled for both component rotation and resultant changes to posterolateral tibial tray overhang and posteromedial underhang. We hypothesize that asymmetrical tibial components can provide greater coverage than symmetrical trays without increasing overhang.

Aims: To find a long-term effect of posterolateral fusion for isthmic spondylolysis and spondylolisthesis on lumbar spine.

Methods: A posterolateral fusion was performed on 56 patients (30 females, 26 males) with an average age of 16 (range 11 to 20) years. A clinical and MRI examination was performed on these patients on average 18 years later (range 11 to 25 years). The size of the spinal canal were assessed. Disc space, degeneration and protrusions were evaluated. Bone marrow changes (Modic I & II), facet joint degeneration and the state of the spinal muscles were assessed.

Results: In MR images, none of the patients had lumbar spinal stenosis. In contrast, the spinal canal was wide in the level spondylolysis and spondylolisthesis. Narrowing of the neural foramina was noted in 13 (23%) patients. This was associated usually in severe slip (> 50%) and was noted always at the L5-S1 level. Of the studied 332 intervertebral discs 56 (17%) were speckled and 57 (17%) were black and 76 (23%) narrowed. Most commonly speckled/black and narrowed disc was found in the two lowest lumbar levels. Only one patient, 41-year-old female, had prolapse. Modic I and II changes were noted in 7 (2%) and 9 (3%) intervertebral disc levels, respectively. Degenerative-like facet joint hypertrophy was noted in 47 (48%) of the studied levels. Of the patients, seven (12%) had muscular atrophy.

Conclusions: Stenosis of neural foramina may be associated to severe spondyolisthesis. Degenerative changes were found most commonly found in the level of the spondylolysis and spondylolisthesis and above fusion level. Bone marrow changes associated with disc degeneration were rare.

Introduction and Aims: To assess the tibiofemoral kinematics of the PCL deficient knee using vertical open-access ‘dynamic’ MRI.

Method: Tibiofemoral motion was assessed using open-access MRI, weight-bearing in a squat, through the arc of flexion from zero to 90 degrees in six patients with isolated rupture of the PCL in one knee [diagnosed from conventional MRI scanning and clinical assessment] and a normal contralateral knee. Mid-medial and mid-lateral sagittal images were analysed in all chosen positions of flexion in both knees to assess the relative tibiofemoral relationships. Passive sagittal laxity was assessed by performing the posterior and anterior drawer tests, while the knees were scanned, again using the same MRI scanner. The tibiofemoral positions during this stress MRI examination was measured from mid-medial and mid-lateral sagittal images of the knees.

Results: Rupture of the PCL leads to an increase in passive sagittal laxity in the medial compartment of the knee [P< 0.006]. In the weight-bearing scans, PCL rupture alters the kinematics of the knee with persistent posterior subluxation of the medial tibia so that the femoral condyle rides up the anterior upslope of the medial tibial plateau. This ‘fixed’ subluxation was observed throughout the extension-flexion arc being statistically significant at all flexion angles (P< 0.018 at 0°, P< 0.013 at 20°, P< 0.014 at 45°, P< 0.004 at 90°). The kinematics of the lateral compartment were not altered by PCL rupture to a statistically significant degree. The posterior drawer test showed increased laxity in the medial compartment.

Conclusion: PCL rupture alters the kinematics of the medial compartment of the knee resulting in ‘fixed’ anterior subluxation of the medial femoral condyle [posterior subluxation of the medial tibial condyle]. This study helps to explain the observation of increased incidence of osteoarthritis in the medial compartment and specifically femoral condyle, in PCL deficient knees.

Abstract. Introduction. Previous research has demonstrated no clinically significant benefit of arthroscopic meniscectomy in patients with a meniscal tear, however, patients included in these studies would not meet current treatment recommendations. Prior to further randomised controlled trials (RCTs) research is needed to understand a younger population in more detail. Aim. To describe the baseline characteristics of patients with a meniscal tear and explore any association between baseline characteristics and outcome. Methodology. A prospective, national multicentre cohort study was performed recruiting patients aged 18 to 55 presenting to secondary care. MRI analysis of arthritis was performed using Whole Organ Magnetic Resonance Imaging Score (WORMS) and bone shape analysis. Outcomes included the Western Ontario Meniscal Evaluation Tool (WOMET) and Knee Injury and Osteoarthritis Outcome Score (KOOS4) at 12 months. Results. 150 participants were recruited across eight sites with a mean age of 43.47 (SD 9.63). MRI analysis using WORMS score and bone shape analysis revealed no or early osteoarthritis. At 12 months, 67 (44.67%) of participants were managed non-operatively and 68 (45.33%) were operatively. Participants in the operative group were significantly younger with a lower BMI (p<0.05). A stepwise logistic regression model including 17 characteristics revealed that only baseline score and surgery significantly affected 12-month WOMET and KOOS4. Conclusion. This study in contrast to previous trials demonstrated a benefit of surgery for patients with a meniscal tear. The METRO study demonstrates that it is feasible to recruit younger patients and a future RCT is required using the study population included in this cohort

Aims. MRI has been suggested as an objective method of assessing anterior crucate ligament (ACL) graft “ligamentization” after reconstruction. It has been proposed that the MRI appearances could be used as an indicator of graft maturity and used as part of a return-to-sport assessment. The aim of this study was to evaluate the correlation between MRI graft signal and postoperative functional scores, anterior knee laxity, and patient age at operation. Methods. A consecutive cohort of 149 patients who had undergone semitendinosus autograft ACL reconstruction, using femoral and tibial adjustable loop fixations, were evaluated retrospectively postoperatively at two years. All underwent MRI analysis of the ACL graft, performed using signal-to-noise quotient (SNQ) and the Howell score. Functional outcome scores (Lysholm, Tegner, International Knee Documentation Committee (IKDC) subjective, and IKDC objective) were obtained and all patients underwent instrumented side-to-side anterior laxity differential laxity testing. Results. Two-year postoperative mean outcome scores were: Tegner 6.5 (2 to 10); Lysholm 89.8 (SD 10.4; 52 to 100); and IKDC subjective 86.8 (SD 11.8; 51 to 100). The objective IKDC score was 86% A (128 patients), 13% B (19 patients), and 1% C (two patients). Mean side-to-side anterior laxity difference (134 N force) was 0.6 mm (SD 1.8; -4.1 to 5.6). Mean graft SNQ was 2.0 (SD 3.5; -14 to 17). Graft Howell scores were I (61%, 91 patients), II (25%, 37 patients), III (13%, 19 patients), and IV (1%, two patients). There was no correlation between either Howell score or SNQ with instrumented anterior or Lysholm, Tegner, and IKDC scores, nor was any correlation found between patient age and ACL graft SNQ or Howell score. Conclusion. The two-year postoperative MRI appearances of four-strand, semitendinosus ACL autografts (as measured by SNQ and Howell score) do not appear to have a relationship with postoperative functional scores, instrumented anterior laxity, or patient age at surgery. Other tools for analysis of graft maturity should be developed. Cite this article: Bone Jt Open 2021;2(8):569–575

Background. Weightbearing computed tomography scans allow for better understanding of foot alignment in patients with Progressive Collapsing Foot Deformity. However, soft tissue integrity cannot be assessed via WBCT. As performing both WBCT and magnetic resonance imaging is not cost effective, we aimed to assess whether there is an association between specific WBCT and MRI findings. Methods. A cohort of 24 patients of various stages of PCFD (mean age 51±18 years) underwent WBCT scans and MRI. In addition to signs of sinus tarsi impingement, four three-dimensional measurements (talo-calcaneal overlap, talo-navicular coverage, Meary's angle axial/lateral) were obtained using a post processing software (DISIOR 2.1, Finland) on the WBCT datasets. Sinus tarsi obliteration, spring ligament complex and tibiospring ligament integrity, as well as tibialis posterior tendon degeneration were evaluated with MRI. Statistical analysis was performed for significant (P<0.05) correlation between findings. Results. None of the assessed 3D measurements correlated with spring ligament complex or tibiospring ligament tears. Age, body mass index, and TCO were associated with tibialis posterior tendon tears. 75% of patients with sinus tarsi impingement on WBCT also showed signs of sinus tarsi obliteration on MRI. Of the assessed parameters, only age and BMI were associated with sinus tarsi obliteration diagnosed on MRI, while the assessed WBCT based 3D measurements were, with the exception of MA axial, associated with sinus tarsi impingement. Conclusion. While WBCT reflects foot alignment and indicates signs of osseous impingement in PCFD patients, the association between WBCT based 3D measurements and ligament or tendon tears in MRI is limited. Partial or complete tears of the tibialis posterior tendon were only detectable in comparably older and overweight PCFD patients with an increased TCO. WBCT does not replace MRI in diagnostic value. Both imaging options add important information and may impact decision-making in the treatment of PCFD patients

Repetitive manual handling caused 31% of all work related musculoskeletal disorders in 2015, with the back being the site of injury 38% of the time. Despite its high resilience, studies have shown that intervertebral discs can be damaged during repetitive loading at physiological motions, causing cumulative damage and disc herniation. To understand the mechanism of disc injury resulting from repetitive lifting, it is important to measure disc deformations/strains accompanied by MRI imaging to identify disc tissue damage. Therefore, the aim of this study was to examine associations between the magnitude of 3D internal strains, tissue damage and macroscopic evidence of disc injury after simulated repetitive lifting on normal human lumbar discs. Sixteen cadaver lumbar functional spinal units (FSUs) were subjected to pre-test MRI. Eight FSUs (control) underwent 20,000 cycles or until failure (5 mm displacement) of loading under compression (1.7 MPa – to simulate lifting a 20 kg weight) + flexion (13°) + right axial rotation (2°) using a novel Hexapod Robot. The remaining eight FSUs (experimental) had a grid of tantalum wires inserted, and stereoradiographs were taken to track internal disc displacements at increasing cyclic intervals. Maximum shear strains (MSS) were calculated from the displacements using radiostereometric analysis at cycle 1 and 20,000 cycles (or failure). Post-test MRI was conducted to determine the extent of tissue damage and associated with regions of highest MSS. A repeated measures ANOVA was performed on MSS with a within–subjects factor of cycle number (cycle 1 and failure cycle) and a between subjects-factor of disc region and failure type (p < 0 .05). Pfirrmann grading revealed mostly normal discs [I (N=2), II (N=13), and III (N=1)]. No significant difference in MSS between control and experimental groups was found for number of cycles to failure (p=0.279). Pre and post-test MRI analysis revealed that 13 specimens were injured after repetitive lifting with either an endplate failure (N=9) or disc bulge (N=4), and two specimens did not fail. Failure strain was significantly greater than cycle 1 in all regions except posterior, left/right posterolateral (p>0.109). Largest MSS at failure was seen in the anterior (60%), and left/right posterolateral regions (64% and 70%, respectively). MSS at failure for the endplate failure group was significantly larger than the no injury group in all regions except right lateral and nucleus (p>0.707). Disc bulge group MSS was significantly larger than the no injury group in the anterior, right anterolateral, and left/right posterolateral regions (p < 0 .027). Simulated repetitive lifting led to largest shear strains in the anterior, left and right posterolateral regions that corresponded to annular tears or annular protrusion. The no injury group shear strain was less than 50% in all regions, indicating there may be a threshold that could be associated with tissue damage linked with injuries such as disc bulge and endplate failure. There was no evidence of disc herniation in normal discs, agreeing with current clinical knowledge. These results may be indicative of the effects of repetitive manual handling on normal discs of younger patients

Surgeon-performed periarticular injection and anesthesiologist-performed femoral nerve or adductor canal block with local anesthetic have been used in multimodal pain management for total knee arthroplasty (TKA) patients. Anesthesiologist-performed adductor canal blocks are costly, time consuming, and may be unreliable. We investigated the feasibility of a surgeon-performed saphenous nerve (“adductor-canal”) block from within the knee joint. A retrospective analysis of 94 thigh-knee MRI studies was performed to determine the relationship between the width of the distal femur at the epicondylar axis and the proximal location of the saphenous nerve after its exit from the adductor canal and separation from the superficial femoral artery. After obtaining these data, TKA resections and trial component implantation were performed, using a medial parapatellar approach, in 11 fresh cadaveric lower extremity specimens. Using a blunt tip 1.5cm needle, we injected 10 ml each of two different colored solutions at two different intra-articular medial injection locations, and after 30 minutes, dissected the femoral and saphenous nerve and femoral artery from the hip to the knee to determine the location of the injections. Based upon the MRI analysis, the saphenous nerve was located (and had exited the adductor canal) at a mean of 1.5 times the epicondylar width in females, and mean 1.3 times the epicondylar width in males, proximal to the medial epicondyle. After placement of TKA trial components and injection, the proximal injection site solution bathed the saphenous nerve in 8 of 11 specimens. The proximal blunt needle and solution was adjacent, but did not puncture, the femoral artery and vein in only one specimen. This study suggests that a surgeon-performed injection of the saphenous nerve from within the knee is a feasible procedure. This technique may be a useful alternative to ultrasound guided block. A trial comparing surgeon and anesthesiologist-performed nerve block should be considered to determine the clinical efficacy of this procedure. Our anecdotal use of this intra-articular injection over the past year has been favorable. Newer, extended release anesthetic agents should be investigated with this technique

Aims

Treatment of high-grade limb bone sarcoma that invades a joint requires en bloc extra-articular excision. MRI can demonstrate joint invasion but is frequently inconclusive, and its predictive value is unknown. We evaluated the diagnostic accuracy of direct and indirect radiological signs of intra-articular tumour extension and the performance characteristics of MRI findings of intra-articular tumour extension.

Aims

Surgical treatment of young femoral neck fractures often requires an open approach to achieve an anatomical reduction. The application of a calcar plate has recently been described to aid in femoral neck fracture reduction and to augment fixation. However, application of a plate may potentially compromise the regional vascularity of the femoral head and neck. The purpose of this study was to investigate the effect of calcar femoral neck plating on the vascularity of the femoral head and neck.

An ACL reconstruction is designed to restore the normal knee function and prevent the onset and progression of degenerative changes such as osteoarthritis. However, contemporary literature provides limited consensus on whether knee degeneration can be attenuated by the reconstruction procedure. The aim of this pilot study was to identify the presence of early osteoarthritis after ACL reconstruction using MRI analysis. 19 patients who had undergone an ACL reconstruction (9 isolated ACL rupture, 8 ACL rupture and meniscectomy, 2 ACL rupture and meniscal repair) volunteered for this study. MRI's were collected preoperatively and postoperatively for analysis with a mean follow up of 23 months. The Boston-Leeds Osteoarthritis Knee Score (BLOKS) was used for the analysis of the articular cartilage by a consultant orthopaedic surgeon. Scores ranged from 0–3, with 0 being total coverage and thickness of the cartilage and 3 being no coverage. Qualitative analysis was then conducted on each patient to determine if the articular cartilage improved, degenerated, or did not change between preoperative and follow-up scans. All patients with isolated ACL rupture were found to either have no change or improved articular cartilage scores in their follow up scans compared preoperatively. In contrast, patients with a meniscal repair displayed worse cartilage scores postoperatively. Lastly, of the patients who had an associated meniscectomy, 6 had worse follow-up results, with the remaining patients showing no change or improved cartilage scores. The present results indicate that patients with an isolated ACL rupture have a reduced risk of developing OA compared to those with associated meniscal injuries. This has implications for analysing the outcome of current ACL reconstruction techniques and in predicting the likelihood of patients developing OA after ACL reconstruction. Future work will involve confirming this pattern in a larger patient sample, as well as exploring additional factors such as time to surgery delay and rehabilitation strategy

In the large majority of cases of knee osteoarthritis (OA), total knee replacement (TKA) is the selected treatment, due to its proven durability, satisfactory function and familiarity of surgeons. However in recent years there has been an increase in the numbers of uni-compartmental knees used (UKA), due to more favorable follow-up, improved designs and techniques, quicker and better patient recovery, and less hospitalization costs. Designs have been produced for even lesser invasive components than UKA, including simple spacers, with mixed results. Recently, several studies have been carried out on the wear patterns on the femoral and tibial condyles in OA, showing that the main areas of cartilage loss occur on the distal end of the femur, that area engaged in walking activities, and over a large proportion of the tibial plateau. A study we carried out on the bone pieces resected at TKA surgery showed that no less than 22% of the cases could have been done with a device which resurfaced only the medial side. That figure would have been higher if the patients had been treated earlier, before cartilage wear and deformation had progressed. In a more recent study, we showed the progress of the wear of OA by analyzing MRI scans of 50 patients at various stages of OA. The cartilage wear occurred on areas which were initially the thickest on both the femur and the tibia. This was evidently associated with excessive contact stresses, while the menisci, if they had previously been spreading the load over a large area of the cartilage surfaces, were no longer functional. In this paper it is proposed that the treatment modality of OA could be carried out on a sliding scale, based on MRI analysis together with clinical factors including pain and disability. Early Intervention devices, including UKA, could be used much more frequently if the surgical technique was developed to be reliable, simple and reproducible. Specifically there is space for an Early Intervention device (EI) where only the distal end of the femur and the tibial surface are resurfaced. A design has been produced where a pocket is milled into the distal end of the femur to house a plastic runner, and a thin layer is resected from the proximal tibia for a metal plate with a special keel design. The advantages of such a design are ease of exposure, accurate and simple surgery, minimal tibial resection for long term fixation, reduced wear, and ease of restoration of the original joint line. The wear is assessed using a custom-made wear machine, while fixation is evaluated using FEA. It is proposed that such a device would add a valuable option for the treatment of symptomatic early OA where the functional level of the patient can be maintained, and the progress of OA possibly arrested

Background: Time dependent, quantitative studies of muscle atrophy or passive muscle mechanics following chronic muscle detachment have not been previously reported. We developed a chronic tear of the rotator cuff tendon in a canine model to investigate and quantify the time related changes in the passive mechanics, volume, and fat of the infraspinatus muscle. We hypothesize that infraspinatus muscle stiffness will increase, volume will decrease, and fat content will increase at 12-weeks following tendon detachment. Methods: The right infraspinatus tendons of eight adult mongrel dogs were surgically detached from the proximal humerus. The non-operated left shoulder served as a control. Muscle volume changes were quantified using MRI scans. At 12 weeks the passive mechanical properties of the chronically detached and control muscles were determined intraoperatively using a custom device. Intramuscular fat was evaluated histologically at sacrifice. Results: After 12 weeks of detachment, the stiffness and modulus were significantly increased in the detached infraspinatus muscles relative to controls. MRI analysis demonstrated that the detached muscle volumes decreased by 33 percent in the first 6 weeks and remained constant thereafter. Intramuscular fat increased significantly in the detached muscles, and to a greater extent in the lateral regions. Conclusions: The chronically detached muscle is not merely a smaller version of the original muscle but rather a “different” muscle. The detached muscle becomes stiffer and the passive loads required to repair it can become excessive. A significant reduction in muscle volume occurs within days to weeks following tendon detachment. The non-uniformity of muscle fat changes suggests that fat content should be used cautiously as an indicator of muscle quality. Clinical Relevance: Clinically, chronic, large rotator cuff tendon tears are observed to have a qualitatively shorter and stiffer muscle-tendon unit than normal. We have developed a chronic rotator cuff model to quantitatively investigate changes in the detached infraspinatus muscle. The passive mechanical properties of a chronically torn rotator cuff muscle-tendon unit may be a useful predictor of reparability and clinical outcome