Abstract. Objectives. Stiffness is reported in 4%–16% of patients after having undergone total knee replacement (TKR). Limitation to range of motion (ROM) can limit a patient's ability to undertake activities of daily living with a knee flexion of 83. o. , 93. o. , and 106. o. required to walk up stairs, sit on a chair, and tie one's shoelaces respectively. The treatment of stiffness after TKR remains a challenge. Many treatment options are described for treating the stiff TKR. In addition to physiotherapy the most employed of these is manipulation under anaesthesia (MUA). MUA accounts for up to 36% of readmissions following TKR. Though frequently undertaken the outcomes of MUA remain variable and unpredictable. CPM as an adjuvant therapy to MUA remains the subject of debate. Combining the use of CPM after MUA in theory adds the potential benefits of CPM to those of MUA potentially offering greater improvements in ROM. This paper reports a retrospective study comparing patients who underwent MUA with and without post-operative CPM. Methods. Standard practice in our institution is for patients undergoing MUA for stiff TKR to receive CPM for between 12–24hours post-operatively. Owing to the COVID-19 pandemic hospital admissions were limited. During this period several MUA procedures were undertaken without subsequent inpatient CPM. We retrospectively identified two cohorts of patients treated for stiff TKR: group 1) MUA + post-operative CPM 2) Daycase MUA. All patients had undergone initial physiotherapy to try and improve their ROM prior to proceeding to MUA. In addition to patients’ demographics pre-manipulation ROM, post-MUA ROM, and ROM at final follow-up were recorded for each patient. Results. In total 168 patients who had undergone MUA between 2017–2022 were identified with a median Age of 66.5 years and 64% female. 57% had extension deficit (>5. o. ), 70% had flexion deficit (< 90. o. ), and 37% had both. 42 had daycase MUA without CPM and the remaining 126 were admitted for post-operative CPM. The mean Pre-operative ROM was 72.3. o. (SD:18.3. o. ) and 68.5. o. (19.0. o. ) for the daycase and CPM groups respectively. The mean ROM recorded at MUA was 95.5. o. (SD:20.7. o. ) and 108.3. o. (SD:14.1. o. ) [p<0.01] and at final follow-up was 87.4o (SD:21.9o) and 92.1o (SD:18.2o) for daycase and CPM groups respectively. At final follow-up for the daycase and CPM groups respectively 10% vs. 7% improved, 29% vs. 13% maintained, and 57% vs. 79% regressed from the ROM achieved at MUA. The mean percentage of ROM gained at MUA maintained at final follow-up was 92% (SD:17%) and 85% (SD:14%) [p=0.03] for daycase and CPM groups respectively. Conclusion. Overall, there was no significant difference in ROM achieved at final follow-up despite the significantly greater improvement in ROM achieved at MUA for the CPM group. Analysis of the percentage ROM gained at MUA maintained at follow up showed that most patients regressed from ROM achieved at MUA in both groups with those in the CPM only maintaining 85% as opposed to 92% in the daycase patients. It is our observation that post-operative CPM does not improve ROM achieved after MUA as compared to MUA alone. 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

Stiffness is reported in up to 16% of patients after total knee replacement (TKR). 1. Treatment of stiffness after TKR remains a challenge. Manipulation under anaesthesia (MUA) accounts for between 6%-36% of readmissions following TKR. 2,3. The outcomes of MUA remain variable/unpredictable. Post-operative CPM is used as an adjuvant to MUA, potentially offering improved ROM, however, remains the subject of debate. We report a retrospective study comparing MUA with and without post-operative CPM. In our institution patients undergoing MUA to receive CPM post-operatively. Owing to the COVID-19 pandemic hospital admissions were limited. During this period MUA procedures were undertaken without CPM. Two cohorts were included: 1) MUA + post-operative CPM 2) Daycase MUA. Patients’ demographics, pre-manipulation ROM, post-MUA ROM, and ROM at final follow-up were recorded. Between 2017-2022 126 patients underwent MUA and were admitted for CPM and 42 had daycase MUA. The median Age was 66.5 and 64% were female. 57% had extension deficit (>5. o. ), 70% had flexion deficit (< 90. o. ), and 37% had both. The mean Pre-operative ROM was 72.3. o. (SD:18.3. o. ) vs. 68.5. o. (19.0. o. ), ROM at MUA was 95.5. o. (SD:20.7. o. ) vs 108.3. o. (SD:14.1. o. ) [p< 0.01], and at final follow-up 87.4. o. (SD:21.9. o. ) vs. 92.1. o. (SD:18.2. o. ) for daycase and CPM groups respectively. At final follow-up for the daycase and CPM groups respectively 10% vs. 7% improved, 29% vs. 13% maintained, and 57% vs. 79% regressed from the ROM achieved at MUA. The mean percentage of ROM gained at MUA maintained at final follow-up was 92%(SD:17) and 85%(SD:14)[p=0.03] for daycase and CPM groups respectively. There was no significant difference in ROM achieved at final follow-up despite the significantly greater improvement in ROM achieved at MUA for the CPM group. The CPM group lost a greater ROM after MUA (15% vs. 8%). We conclude that post-operative CPM does not improve ROM achieved after MUA

Abstract. Introduction. All-tissue quadriceps tendon (QT) is becoming an increasingly popular alternative to hamstrings tendon (HT) and bone-tendon-bone (BTB) autograft for anterior cruciate ligament (ACL) reconstruction. The relatively short graft length however dictates that one, or both, ends rely on suture fixation. The strength of this construct is therefore extremely important. This study evaluates whether the use of a novel fixation technique can improve the tensile properties of the construct compared to a Krackow suture, and a looped tendon (suture free) gold standard. Methods. Eighteen porcine flexor tendons were tested, across three groups; suture-tape Krackow, looped tendon, and the novel ‘strain suture’. Biomechanical testing simulated the different stages of ACL graft preparation and loading (60N preload for 10 minutes, 10 cycles from 10N to 75N, and 1000 cycles from 100N to 400N). Elongation and load to failure were recorded, and stiffness calculated for each construct. Results. The mean elongation was significantly improved for the strain suture compared to the suture tape Krackow for preload, 10 cycle and 1000 cycle testing protocols respectively (1.36mm vs 4.93mm, p<001; 0.60mm vs 2.72mm, p<0.001; 2.95mm vs 29.08mm, p<0.001). Compared with the looped tendon, the strain suture demonstrated similar results for preload and 10 cycle elongation, but greater elongation during the 1000 cycle stage. Stiffness of the latter two constructs was similar. Conclusions. Augmentation of the suture fixation using this novel technique provides a construct that is significantly superior to currently practised suture techniques, and similar in elongation and stiffness to a looped graft

Introduction: Stiffness after primary total knee arthroplasty (TKA) is a severe complication that has been associated with excessive internal rotation of the femoral component. Methods: Between 2001 and 2004, 18 patients with 18 well-fixed, aseptic primary TKA underwent revision TKA at a single high-volume joint replacement center for stiffness in the presence of femoral component mal-rotation. Stiffness was defined as ROM with less than 90° of maximum flexion or a flexion contracture greater than 10°. Femoral component malrotation was defined as a condylar twist angle of more than 4° of internal rotation using CT scans. Following IRB approval, 17 out of 18 patients (median age at time of the index surgery 62.7 years, range 45 to 78; female, n=11; male, n=6) were available for retrospective outcome assessment. The mean time between primary and revision TKA was 3.2 years (range, 9–79 months). At a mean follow-up of 3.3 years (range, 2 to 6), all patients were evaluated clinically using the Knee Society objective and functional scores, and by CT measurement of femoral component rotation. Patients without additional procedures between primary and index revision TKA (group A, n=9) were compared using Student t-testing with those which had undergone additional interventions (group B, n=8). Results: Five patients had required additional procedures after the index revision TKA including closed manipulation under anesthesia in one case, patellar resurfacing in one case, metal removal after tubercle osteotomy and open debridement in another case, and tibial component revision followed by revision TKA in one case. CT scans after revision TKA revealed correction of femoral component rotation in all but one case from each group. After revision TKA, the mean objective score was overall 73 points, in group A 82 points compared to 63 points in group B (p< 0.001). In group A there were 78% excellent or good results compared to 13% in group B. The mean function score was overall 74 points, 78 points in group A compared to 69 points in group B. There were 67% good or excellent results in group A compared to 12% in group B. Mean flex-ion increased overall from 71 to 92 degrees (p< 0.01), in group A from 61 to 96 degrees (p< 0.01) and in group B from 82 to 89 degrees. Mean flexion contracture was reduced overall from 7 to 4 degrees, in group A from 6 to 3 degrees, and in group B from 8 to 5 degrees. Stiffness persisted in four cases (24%) (group A, n=1; group B, n=3). Satisfaction (VAS 0–100; 100=completely satis-fied) scored overall a mean of 52 points, in group A 57 points and in group B 44 points. Conclusion: Overall, revision TKA for knee stiffness associated with femoral component internal malrotation resulted in significantly improved knee motion. However, outcome was less predictable in those patients with additional procedures between primary and revision TKA

Introduction. Stiffness after total knee arthroplasty (TKA) has been reported to occur due to component malpositioning and/or oversizing, improper femoral component (FC) flexion and tibial component (TC) slope, tight extension gap, inaccurate joint line placement, deficient posterior osteophyte resection, heterotopic ossification (HO), poor patellofemoral joint reconstruction, poor posterior condylar offset restoration, and/or posterior cruciate ligament (PCL) under-resection or retraction. However, the importance of these potential factors for stiffness are not well documented in the medical literature. The aim of this study was therefore to evaluate specific radiographic parameters in patients who had stiffness after primary TKA. Material and Methods. An IRB-approved retrospective chart review was performed to identify patients that were revised due to stiffness after TKA. We defined stiffness as 15º or more of flexion contraction, less than 75º of flexion or a range of motion (ROM) of 90º with the chief complaint of limited ROM and pain. Patients with history of previous revisions and/or ORIF, infection, or isolated polyethylene exchange were excluded. Patients with a minimum of 1 year radiographic follow-up were included. Radiographic measurements were performed as described by the Knee Society TKA Roentgenographic Evaluation System (KSRES). Two blinded observers performed all measurements. Descriptive data is reported as mean (range). Inter-observer correlations were reported using Intraclass correlations coefficient (ICC). Results. A total of 44 patients met the inclusion criteria. Of those, 13 (30%) were male and 31 (70%) were female. Mean BMI was 33.9 kg/m2 (19.5–58). ICCs ranged from good to excellent (>0.8) for all measurements performed. Coronal FC and TC alignments were 95.29º (82.4º–100.6º) and 89.16º (84.4º–94.2º) respectively. HO ranged from 0 to 3 (0:43%, 1:36%, 2:11%, 3:10%). FC-Flexion and TC-slope were 10.17 (3.5–19.8) and 86.7 (61.2–99.2) respectively. Insall-Salvati ratio was 1.01 (0.58–2.04). Posterior condylar offset (CO) ratio was 0.51 (0.34–1.11). Anterior CO ratio was 0.2 (0–0.34). Anterior femoral cortex notching ranged from 0 to 3 (0:39%, 1:43%, 2:14%, 3:4%). Femoral posterior osteophytes were observed in 32% of patients. A gap between the anterior flange and the femoral cortex was observed in 45% of patients. The patella was resurfaced in 93% of patients with a mean patellar tilt and patellar displacement of 5.34º (−8.9º to 5.34º) and 9.88% (−5 to 41%) respectively. Conclusion. To our knowledge this is the first study reporting specific radiographic data on postoperative stiffness following primary TKA. From the observed radiographic measurements, the increased mean femoral component flexion, the high amount of postoperative HO and posterior osteophytes, and the anterior cortical and component gap suggest possible risk factors influencing the occurrence of postoperative stiffness. Future focus will include a matched control population of patients in order to establish statistical significance of all observed values

Aims. Anchorage of pedicle screw rod instrumentation in the elderly spine with poor bone quality remains challenging. Our study aims to evaluate how the screw bone anchorage is affected by screw design, bone quality, loading conditions, and cementing techniques. Methods. Micro-finite element (µFE) models were created from micro-CT (μCT) scans of vertebrae implanted with two types of pedicle screws (L: Ennovate and R: S. 4. ). Simulations were conducted for a 10 mm radius region of interest (ROI) around each screw and for a full vertebra (FV) where different cementing scenarios were simulated around the screw tips. Stiffness was calculated in pull-out and anterior bending loads. Results. Experimental pull-out strengths were excellently correlated to the µFE pull-out stiffness of the ROI (R. 2. > 0.87) and FV (R. 2. > 0.84) models. No significant difference due to screw design was observed. Cement augmentation increased pull-out stiffness by up to 94% and 48% for L and R screws, respectively, but only increased bending stiffness by up to 6.9% and 1.5%, respectively. Cementing involving only one screw tip resulted in lower stiffness increases in all tested screw designs and loading cases. The stiffening effect of cement augmentation on pull-out and bending stiffness was strongly and negatively correlated to local bone density around the screw (correlation coefficient (R) = -0.95). Conclusion. This combined experimental, µCT and µFE study showed that regional analyses may be sufficient to predict fixation strength in pull-out and that full analyses could show that cement augmentation around pedicle screws increased fixation stiffness in both pull-out and bending, especially for low-density bone. Cite this article: Bone Joint Res 2021;10(12):797–806

Shoulder arthroplasty is effective at restoring function and relieving pain in patients suffering from glenohumeral arthritis; however, cortex thinning has been significantly associated with larger press-fit stems (fill ratio = 0.57 vs 0.48; P = 0.013)1. Additionally, excessively stiff implant-bone constructs are considered undesirable, as high initial stiffness of rigid fracture fixation implants has been related to premature loosening and an ultimate failure of the implant-bone interface2. Consequently, one objective which has driven the evolution of humeral stem design has been the reduction of stress-shielding induced bone resorption; this in-part has led to the introduction of short stems, which rely on metaphyseal fixation. However, the selection of short stem diametral (i.e., thickness) sizing remains subjective, and its impact on the resulting stem-bone construct stiffness has yet to be quantified.

Eight paired cadaveric humeri (age = 75±15 years) were reconstructed with surgeon selected ‘standard’ sized and 2mm ‘oversized’ short-stemmed implants. Standard stem sizing was based on a haptic assessment of stem and broach stability per typical surgical practice. Anteroposterior radiographs were taken, and the metaphyseal and diaphyseal fill ratios were quantified. Each humerus was then potted in polymethyl methacrylate bone cement and subjected to 2000 cycles of compressive loading representing 90º forward flexion to simulate postoperative seating. Following this, a custom 3D printed metal implant adapter was affixed to the stem, which allowed for compressive loading in-line with the stem axis (Fig.1). Each stem was then forced to subside by 5mm at a rate of 1mm/min, from which the compressive stiffness of the stem-bone construct was assessed. The bone-implant construct stiffness was quantified as the slope of the linear portion of the resulting force-displacement curves.

The metaphyseal and diaphyseal fill ratios were 0.50±0.10 and 0.45±0.07 for the standard sized stems and 0.50±0.06 and 0.52±0.06 for the oversized stems, respectively. Neither was found to correlate significantly with the stem-bone construct stiffness measure (metaphysis: P = 0.259, diaphysis: P = 0.529); however, the diaphyseal fill ratio was significantly different between standard and oversized stems (P < 0.001, Power = 1.0). Increasing the stem size by 2mm had a significant impact on the stiffness of the stem-bone construct (P = 0.003, Power = 0.971; Fig.2). Stem oversizing yielded a construct stiffness of −741±243N/mm; more than double that of the standard stems, which was −334±120N/mm.

The fill ratios reported in the present investigation match well with those of a finite element assessment of oversizing short humeral stems3. This work complements that investigation's conclusion, that small reductions in diaphyseal fill ratio may reduce the likelihood of stress shielding, by also demonstrating that oversizing stems by 2mm dramatically increases the stiffness of the resulting implant-bone construct, as stiffer implants have been associated with decreased bone stimulus4 and premature loosening2. The present findings suggest that even a small, 2mm, variation in the thickness of short stem humeral components can have a marked influence on the resulting stiffness of the implant-bone construct. This highlights the need for more objective intraoperative methods for selecting stem size to provide guidelines for appropriate diametral sizing.

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Aims: The aims of this study were to define the incidence of knee stiffness following ACL reconstruction, to determine which patient factors were associated with this, and to assess how effective arthroscopic arthrolysis has been in treating the stiffness. Methods: To define the incidence of stiffness, we reviewed the patient records of a consecutive cohort of 100 primary isolated ACL reconstructions using quadruple hamstring autografts (2004–2006). Stiffness was defined as any loss of motion as compared to the contra-lateral leg. The mean age at reconstruction was 30 years and the median delay between injury and operation was 15 months. To assess the effectiveness of arthroscopic arthrolysis, we then reviewed all the patients who had undergone this procedure following primary isolated ACL reconstruction (n=18: 1997–2008). The mean age at arthrolysis was 31 years and the median delay between reconstruction and arthrolysis was nine months. Results: Following primary ACL reconstruction, the incidence of stiffness was 12% six months postoperatively. Poor compliance with physiotherapy (p< 0.005), previous knee surgery (p< 0.005), and anterior knee pain (p< 0.029) were significantly associated with stiffness. A binary logistic regression found both poor compliance with physiotherapy (Exp(B)=6.931; 95%CI, 1.609–29.859; p< 0.009) and previous knee surgery (Exp(B)=6.383; 95%CI, 1.548–26.322; p< 0.010) to be significant predictors of the stiffness. The rate of stiffness fell to 5% at 12 months, without operative intervention. Of the 18 patients who underwent arthroscopic arthrolysis, the mean extension loss improved from 7° to 1° and the mean flexion loss improved from 8° to 2°. Arthroscopic arthrolysis was significantly more effective in restoring extension loss (p< 0.029) if carried out within eight months of the primary reconstruction. Conclusions: Knee stiffness remains a significant problem post ACL reconstruction. This can however be effectively improved by appropriately timed arthroscopic arthrolysis

Introduction: Stiffness is a disabling problem following TKR surgery. The overall incidence is 1–3%. Though multiple factors have been implicated in development of stiffness, it still remains an incompletely understood condition. Furthermore, opinion is divided about the efficacy, timing and the number of MUA’s post TKR surgery, as there are no definitive guidelines. Aims & Objectives: The aim of this study was to assess the predisposing factors for stiffness following TKR surgery, to determine the efficacy of single and multiple manipulations and to investigate the most appropriate timing for manipulation. Material & Methods: We retrospectively reviewed 86 patients who underwent manipulation for stiffness post-primary TKR surgery with at least one-year follow up. The number of manipulations, predisposing factors, the flexion gain at different intervals, final gain in flexion and range of movement was noted till the end of 1 year. Results: Results were assessed by timing and number of MUA’s performed. Sixty five patients underwent single MUA and 21 had multiple MUA. At the end of one year the single MUA group showed 310 of sustained gain in flexion and in the multiple MUA group only 90 flexion gain was noted (p=0.003). MUA within 20 weeks of primary surgery showed 300 of flexion gain, whereas only 70 of flexion gain was seen when MUA was undertaken after 20 weeks (p=0.004). Patients on warfarin (9.5%) and with previous major surgeries to the knee prior to TKR (11.5%) had increase incidence of stiffness and poor flexion gain. Conclusion: The timing of the 1st MUA is crucial, with better results achieved in MUA performed less than 20 weeks (particularly between 12–14 weeks) from primary surgery. Age, sex and type of disease do not influence the severity of stiffness in this study. There appears to be no added benefit in re-manipulation

As high incidences of tendinopathies are observed particularly in those who intensively use their tendons, we assume that pathological changes are caused, at least partially, by mechanical overload. This has led to the so-called overload hypothesis, explaining the development of tendinopathies by structural failure resulting from excessive load. At the same time, tendon loading is an important part in tendon rehabilitation. Currently, exercise treatment approaches such as eccentric training or heavy load resistance training are widely applied in tendinopathy rehabilitation, with good clinical results such as an improvement in function and a reduction in pain. Particularly those rehabilitative approaches which impose high strains on the tendon may induce an adaptation of the tendon's mechanical properties such as increased tendon stiffness. An increased tendon stiffness is often interpreted as desirable, as it may protect the tendon from overloading and thus prevent future strain injuries. However, the tendinopathic tendon is not necessarily less stiff than the tendon in the contralateral leg and an improvement in tendon stiffness is not necessarily accompanied by an improvement in tendon pain or function. In addition, metabolic factors, resulting e.g. in low-level systemic inflammation, may contribute to pathological tendon tissue changes and are not necessarily affected by an exercise program, while nutritional interventions or dietary supplements may potentially affect tendon cell metabolism. Indeed, dietary supplements have been introduced as an additional therapeutic approach in the treatment of tendinopathies in recent years, and their positive curative effects have been reported for both the general population and athletes. In the management of tendinopathies, it may thus be advisable if therapeutic approaches aim to address both tendon mechanics and tendon metabolism for better treatment effectiveness and a sustainable improvement in pain and function.

Objectives. The ability to determine human bone stiffness is of clinical relevance in many fields, including bone quality assessment and orthopaedic prosthesis design. Stiffness can be measured using compression testing, an experimental technique commonly used to test bone specimens in vitro. This systematic review aims to determine how best to perform compression testing of human bone. Methods. A keyword search of all English language articles up until December 2017 of compression testing of bone was undertaken in Medline, Embase, PubMed, and Scopus databases. Studies using bulk tissue, animal tissue, whole bone, or testing techniques other than compression testing were excluded. Results. A total of 4712 abstracts were retrieved, with 177 papers included in the analysis; 20 studies directly analyzed the compression testing technique to improve the accuracy of testing. Several influencing factors should be considered when testing bone samples in compression. These include the method of data analysis, specimen storage, specimen preparation, testing configuration, and loading protocol. Conclusion. Compression testing is a widely used technique for measuring the stiffness of bone but there is a great deal of inter-study variation in experimental techniques across the literature. Based on best evidence from the literature, suggestions for bone compression testing are made in this review, although further studies are needed to establish standardized bone testing techniques in order to increase the comparability and reliability of bone stiffness studies. Cite this article: S. Zhao, M. Arnold, S. Ma, R. L. Abel, J. P. Cobb, U. Hansen, O. Boughton. Standardizing compression testing for measuring the stiffness of human bone. Bone Joint Res 2018;7:524–538. DOI: 10.1302/2046-3758.78.BJR-2018-0025.R1

Purpose of the study: Stiffness of the ankle joint is a common complication after fracture, surgical repair, or total ankle arthroplasty. Dorsiflexion is generally the most limited movement. A few older papers have focused on this common problem in orthopaedic surgery of the ankle joint but have been controversial. The purpose of this anatomy study was to evaluate the efficacy and quantify the impact of releasing the collateral ligaments of the ankle joint on dorsiflexion stiffness. Material and methods: The two main ankle ligaments implicated in this type of stiffness, the deep bundle of the posterior tibiotalar ligament (dPTTaL) and the posterior talofibular ligament (PTaFL), were studied. We dissected 16 talocrural joints on fresh cadavers and measured with electronic goniometry coupled with electronic dynamometry their movement in dorsiflexion after section of the dPTTaL in the first group and after section of the PTaFL in the second. Results: The results showed a significant difference (p< 0.0003) between the two populations of ankles. Section of the dPTTaL was more effective against dorsiflexion stiffness than section of the PTaFL, even though the overall benefit in dorsiflexion was less than 10° (mean 7.45 versus 3.45). Combined section of the two ligaments did not provide a statistically significant improvement in the gain in dorsiflextion (p=0.88) compared with isolated section of the two ligaments. Discussion: If limitation of active and passive dorsiflexion persists after classical release or lengthening of the posterior periarticular tendons of the ankle joint, or after gastrocnemius lengthening, our results show that the following surgical step could be meticulous release of the dPTTaL

Purpose: To determine the relationship between the in vivo indentation stiffness and indices of histopathological degeneration of human knee articular cartilage. Materials and Methods: Cartilage compressive stiffness was measured in 98 patients during in vivo knee arthroscopies. The age of the patients ranged from 21 to 63 years (mean age 29 years). Male to female ratio of the patients was 37:61. The measurements were performed at eight standard sites. No chondropathic or grade I. chondropathic surfaces were measured. An indentation instrument, Artscan 1000, was used for in vivo measurements. Four plugs were harvested from each knee for histological analysis. The stage of cartilage degeneration was assessed according to Mankin histolopathology score. 16 measurements were performed after ACI. Results: Lateral femoral condyle stiffness (mean + SD; 5.12 ±1.02N) was greater than all other sites and was significantly greater than mean values obtained for medial femoral condyle (4.8 ± 1.22N); medial and lateral trochlea (4.2 + 0.92, 4.6 + 1.27N), medial (3.1 ± 0.66N) and lateral patella (3.3 ± 1.01N); and medial and lateral tibial condyle for all subjects (2.4 ± 1.17N and 3.2 ± 1.16N). The dynamic modulus of the normal or mildly degenerated cartilage correlated negatively with the Mankin score: r (Spearman) = −0.823, n = 348. Stiffness at the repaired site was similar to normal cartilage at adjacent sites in the knee. Conclusion: The high negative correlation between stiffness and the Mankin score suggests that the stage of cartilage degeneration can be quantitatively and indirectly assessed with a hand-held instrument during arthroscopy

Purpose: To determine the relationship between the in vivo indentation stiffness and indices of histopathological degeneration of human knee articular cartilage. Materials and Methods: Cartilage compressive stiffness was measured in 98 patients during in vivo knee arthroscopies. The age of the patients ranged from 21 to 63 years (mean age 29 years). Male to female ratio of the patients was 37:61. The measurements were performed at eight standard sites. No chondropathic or grade I. chondropathic surfaces were measured. An indentation instrument, Artscan 1000, was used for in vivo measurements. Four plugs were harvested from each knee for histological analysis. The stage of cartilage degeneration was assessed according to Mankin histolopathology score. 16 measurements were performed after ACI. Results: Lateral femoral condyle stiffness (mean + SD; 5.12 ±1.02N) was greater than all other sites and was significantly greater than mean values obtained for medial femoral condyle (4.8 ± 1.22N); medial and lateral trochlea (4.2 + 0.92, 4.6 + 1.27N), medial (3.1 ± 0.66N) and lateral patella (3.3 ± 1.01N); and medial and lateral tibial condyle for all subjects (2.4 ± 1.17N and 3.2 ± 1.16N). The dynamic modulus of the normal or mildly degenerated cartilage correlated negatively with the Mankin score: r (Spearman) = −0.823, n =. 348. All visually degenerated samples were softer (dynamic modulus < 2.9 Mpa) than the visually and histologically normal samples (dynamic modulus = 14.7 + 2.9 MPa). Stiffness at the repaired site was similar to normal cartilage at adjacent sites in the knee. Conclusion: The high negative correlation between stiffness and the Mankin score suggests that the stage of cartilage degeneration can be quantitatively and indirectly assessed with a hand-held instrument during arthroscopy

Decreased ankle dorsiflexion is common after injury and may result in patient complaints of stiffness and subsequent injury. The weight-bearing lunge test (WBLT) is a simple clinical measure of dorsiflexion. Previous study has defined a 2.0cm side-to-side discrepancy in WBLT as likely significant. With review of current literature, ankle stiffness is a concept largely undefined; we aim to relate patient complaints of stiffness to WBLT.

This was a population-based inception cohort with longitudinal follow-up. Patients between ages 18–65 receiving surgical fixation for ankle fracture were screened. Pilon/plafond fractures, bilateral injuries, or polytrauma were excluded. At 6-weeks, 6-months, and 1-year WBLT was measured along with non-weight-bearing goniometry; and an Olerud-Molander ankle score completed.

155 patients were recruited (90 female, 65 male; mean age 42, range 20–67). 47% of injuries were unimalleolar, 17% bimalleolar, and 36% trimalleolar; 35% received syndesmotic fixation. 89% of patients reported feeling stiff at 6-weeks, 82% at 6-months, and 74% at 1-year. 98% of patients had ≥2.0cm discrepancy of WBLT at 6-weeks, 78% at 6-months, and 72% at 1-year. Different thresholds of WBLT (larger discrepancy or absolute negative measurement) had worse correlation with patient reported stiffness.

Our population had high incidence of stiffness at 1-year. The proportion of patients complaining of stiffness after ankle fracture was similar to that measured with ≥2.0cm discrepancy of WBLT. This is the first study that we are aware of that relates the WBLT and the previously reported threshold of 2.0cm to stiffness. This measurement may give clinicians a better objective idea regarding patient perception of a “stiff” ankle. Reducing side to side discrepancy in range of motion should be considered in rehabilitation rather than total range of motion.

Mesenchymal stem cells (MSC) have potent immunomodulatory and regenerative effects via soluble factors. One approach to improve stem cell-based therapies is encapsulation of MSC in hydrogels based on natural proteins such as collagen and fibrin, which play critical roles in bone healing. In this work, we comparatively studied the influence of collagen and fibrin hydrogels of varying stiffness on the paracrine interactions established by MSC with macrophages and osteoblasts.

Type I collagen and fibrin hydrogels in a similar stiffness range loaded with MSC from donants were prepared by modifying the protein concentration. Viability and morphology of MSC in hydrogels as well as cell migration rate from the matrices were determined. Paracrine actions of MSC in hydrogels were evaluated in co-cultures with human macrophages from healthy blood donors or with osteoblasts from bone explants of patients with osteonecrosis of the femoral head.

Lower matrix stiffness resulted in higher MSC viability and migration. Cell migration rate from collagen hydrogels was higher than from fibrin matrices. The secretion of the immunomodulatory factors interleukin-6 (IL-6) and prostaglandin E₂ (PGE₂) by MSC in both collagen and fibrin hydrogels increased with increasing matrix stiffness. Tumor necrosis factor-α (TNF-α) secretion by macrophages cultured on collagen hydrogels was lower than on fibrin matrices. Interestingly, higher collagen matrix stiffness resulted in lower secreted TNF-α while the trend was opposite on fibrin hydrogels. In all cases, TNF-α levels were lower when macrophages were cultured on hydrogels containing MSC than on empty gels, an effect partially mediated by PGE₂. Finally, mineralization capacity of osteoblasts co-cultured with MSC in hydrogels increased with increasing matrix stiffness, although this effect was more notably for collagen hydrogels.

Paracrine interactions established by MSC in hydrogels with macrophages and osteoblasts are regulated by matrix composition and stiffness.

Introduction: Non-invasive prediction of load bearing capacity during consolidation of distraction osteogenesis and fracture healing would represent a significant advance in the treatment of patients by defining the appropriate point of time for the removal of the fixator externe. Thereby the risk of refracture, malunion and infection could be reduced. Several methods have been proposed in the past to predict the load bearing capacity: dual-energy x-ray absorptiometry (DEXA), stiffness measurements, quantitative computed tomography, quantitative radiography and ultrasound. In this ex-vivo study stiffness- and DEXA-measurements were compared regarding their suitability to predict the load bearing capacity of bone regenerate. In addition this study analysed how compressive, bending and torsional stiffness as suitable tools were related to the torsional load bearing capacity using a common set of bone regenerate samples of 26 sheep treated with distraction osteogenesis. Material and Methods: After osteotomy the sheep tibiae were stabilized using an external half-ring Ilizarov fixator. Followed by a 4-day latency period the tibiae were distracted at a rate of 1.25 mm per day in two increments for 20 days. On the 74th day the sheep were sacrificed and tibiae were harvested. The ends of the specimens were embedded in PMMA for further biomechanical testing. Therefore, the specimens were mounted to a sequence of special costume made jigs for compressive testing, 4-point bending and torsional testing in a material testing machine. Stiffness was calculated by regression of the linear part of the load-displacement curves. The maximum torsional moment of the specimens was determined in a final experiment. In addition the bone mineral density (BMD) of the distracted bone tissue was measured using DEXA. The correlation between the maximum torsional moment and the various types of stiffness respectively BMD was analysed to gain information about the suitability predicting the load bearing capacity. Results: Torsional stiffness exhibits the highest correlation with the maximum torsional moment (r2 = 0.77) followed by bending (ap (r2 = 0.70); ml (r2 = 0.66)) and compressive stiffness (r2 = 0.60). The correlation for BMD with the maximum torsional moment was smallest (r2 = 0.39). Discussion: This ex-vivo study revealed that the stiffness measurements seem to be a helpful tool to predict the load bearing capacity of bone regenerate. The results of this study showed stiffness measurements as a more suitable mean to determine the load bearing capacity. Within the various types of stiffness measurements torsional stiffness measurements perform slightly better than bending and compressive stiffness measurements. Nevertheless, further studies are necessary to support the results of this study since the specimens failed applying torsional stress

Hemiarthroplasty is a common procedure that is an attractive alternative to total arthroplasty because it conserves natural tissue, allows for quicker recovery, and has a lower cost. One significant issue with hemiarthroplasties is that they lead to accelerated wear of the opposing native cartilage, likely due to the high stiffness of the implant. The purpose of this study was to investigate the range of currently available biomaterials for hemiarthroplasty applications. We employed a finite-element (FE) model of a radial head implant against the native capitellum as our joint model.

The FE model was developed in ABAQUS v6.14 (Dassault Systèmes Simulia Corp., Providence, RI, USA). A solid axisymmetric concave implant with seven different materials and the native radial head were evaluated, six modelled as elastic materials with different Young's moduli (E) and Poisson's Ratios (ν), and one modelled as a Mooney-Rivlin hyperelastic material. The materials investigated were CoCr (E=230 GPa, ν = 0.3), PEEK (E=3.7 GPa, ν = 0.36), HDPE (E=2.7 GPa, ν = 0.42), UHMWPE (E=0.69 GPa, ν = 0.49), Bionate 75D (E=0.288 GPa, ν = 0.39), Bionate 55D (E=0.039 GPa, ν = 0.45), and Bionate 80A (modelled as a Mooney-Rivlin hyperelastic material). A load of 100 N was applied to the radius through the center of rotation representing a typical load through the radius. The variable of interest was articular contact stress on the capitellum.

The CoCr implant had a maximum contact stress over 114% higher than the native radial head. By changing the material to lower the stiffness of the implant, the maximum contact stress was 24%, 70%, 105%, 111%, 113%, and 113% higher than the native radial head for Bionate 80A, Bionate 55D, Bionate 75D, UHMWPE, HDPE, and PEEK respectively.

This work shows that lowering implant stiffness can reduce the contact stress on cartilage in hemiarthroplasty implants. By changing the material below a Young's modulus of ∼100 MPa elevated stresses on the capitellum can be markedly reduced and hence potentially reduce or prevent degenerative changes of the native articulating cartilage. Low stiffness implant materials are not a novel concept, but to date there have been few that investigate materials (such as Bionate) as a potential load bearing material for implant applications. Further work is required to assess the efficacy of these materials for articular bearing applications.

Despite total knee arthroplasty demonstrating high levels of success, 20% of patients report dissatisfaction with their result.

Wellness Stasis Socks are embedded with a proprietary pattern of neuro-receptor activation points that have been proven to activate a precise neuro-response, as according to the pattern theory of haptic perception, which stimulates improvements in pain and function.

Technologies that manipulate this sensory environment, such as textured insoles, have proven to be effective in improving gait patterns in patients with knee osteoarthritis. In regard to patients undergoing TKA using this new technology may prove beneficial as an adjunct to recovery as many patients suffer from further deficits to their proprioceptive system caused by ligamentous damage and alterations to mechanoreceptors during procedure. We hypothesized that the Wellness Stasis Socks are a safe, cost-effective and easily scalable strategy to support TKA patients through their recovery.

Double-blinded, placebo-controlled randomized trial. Randomization using a computer-generated program . All study coordinators, healthcare personel and patients were blinded to patient groups. All surgical procedures were conducted by the same technique and orthopaedic surgeon. Intervention group: Wellness Stasis socks containing receptor point-activation technology. Control group: indentical appearing Wellness Stasis socks without receptor point-activation technology. Sock use during the waking hours . All additional post-operative protocols remained consistent between groups including same facility physiotherapy . Additional modalities (ice machines, soft-tissue massages, acupuncture) were prohibited. WOMAC questionnaire completed at baseline, 2 weeks, and 6 weeks to assess pain, stiffness and physical function. G^*Power software to determine minimum sample of 50 in each group. No patients were lost to follow up and all followed study protocol. Data analysis using SPSS software. P-values, effect sizes, and confidence intervals are reported to assess clinical relevance of the finding. Physical status classifications were compared using t-test. Within-subject and between-subject differences in the mean WOMAC were analyzed by ANOVA.

Cramer's V statistical analysis noted that other variables of Sex, BMI, ASA classification and Age were not statistically different between the control and intervention groups.

No statistical difference between groups in Preop Womac scores.

The data showed a consistent improvement in Womac scores for pain and stiffness at 2 weeks post op in the interventional group over the control group.

The womac scores assessing physical function showed a consistent improvement at both 2 and 6 weeks post op in the intervention group compared to the control group.

There were no complications in either group associated the sock use.

The intervention proved to be a low cost and safe additional intervention post operatively from TKA to help patients improve with regard to pain, stiffness and physical function.

This study suggests this modality can be added to the list of other commonly used post op interventions such as cryocuffs, physiotherapy, and relaxation techniques as safe post op interventions to help patients improve post op TKA and can act as an adjunct in providing non narcotic pain control .

Introduction

The effect of spine-pelvis position and motion on hip arthroplasty function has been increasingly appreciated in the past several years. Some authors have stressed the importance of using precision technologies for component placement while others have advocated the use of dual mobility articulations or large bearings and lateralized liners in patients with fused lumbar spines. The current study assesses the prevalence of stiff and fused spines in an elective total hip arthroplasty population.