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

The postoperative pain after hip arthroscopy remains a major challenge in the immediate postoperative period. Adequate postoperative analgesia has been associated with increased patient satisfaction and decreased consumption of opioids. We evaluated the efficacy of pericapsular nerve group block (PENG) versus fascia iliaca block (FIB) in reducing post-operative pain and analgesic consumption within the first 24 hours following arthroscopic management of femoroacetabular impingement (FAI). Thirty-nine patients (17 females and 25 males, ages 18–42 years, mean ± SD (27.9 ± 6.2), and mean BMI of 25.13±5.08 kg/m2 were scheduled for primary arthroscopic management of FAI. Included patients were randomized into two groups according to the block used in each. Group (A) 19 patients were included and had FIB and group (B) 20 patients were included and received PENG block. The efficacy of both techniques was clinically and statistically valuated using VAS score and quadriceps muscle power. There was a statically significance difference in the mean at rest between the two groups at all measured time points following surgery (6, 12, 18 and 24 h). Also, in dynamic pain scores (with hip flexion) scores were statistically significant at 24 hours post-operative (P = .001). Total opioid consumption in the first 24 hours postoperative was lower in the PENG group with significant difference of mean 16.5 ±9.9 mg for PENG group versus 27.5±9.6 mg for FIB group (P < .005). Five patients (26.31%) in FIB group had weaker quadriceps muscle power while none in PENG group patients had quadriceps weakness. PENG block might be considered as an ideal regional anesthesia modality for hip arthroscopy. As an alternative to more conventional regional nerve blocks such as a fascia iliaca block. PENG block is easily performed in the preoperative setting, and appears to spare motor function while providing a prolonged sensory pain relief

Pain immediately following total knee arthroplasty (TKA) is often severe and can inhibit patients' rehabilitation. Recently, adductor canal blocks have been shown to provide adequate analgesia and spare quadriceps muscle strength in the early postoperative period. We devised a single injection motor sparing knee block (MSB) by targeting the adductor canal and lateral femoral cutaneous nerve with a posterior knee infiltration under ultrasound. Our primary objective was to evaluate the analgesia duration of the MSB in comparison to a standard periarticular infiltration (PAI) analgesia using patients' first rescue analgesia as the end point. Secondary outcomes measured were quadriceps muscle strength and length of stay. We randomised 82 patients scheduled for elective TKA to receive either the preoperative MSB (0.5% ropivacaine, 2.5ug/ml epinephrine, 10mg morphine, and 30mg ketorolac) or intraoperative periarticular infiltration (0.3% ropivacaine, 2.5ug/ml epinephrine, 10mg morphine, and 30mg ketorolac). Duration of analgesia, postoperative quadriceps power, and length of stay were evaluated postoperatively. Analgesic duration was found to be significantly different between groups. The MSB had a mean duration of 18.06 ± 1.68 hours while the PAI group had a mean duration of 9.25 ± 1.68 hours for a mean difference of 8.8 hours (95% CI 3.98 to 13.62), p<0.01. There were no significant differences between groups in quadriceps muscle strength power at 20 minutes (p=0.91) or 6 hours (p=0.66) after block administration. Length of stay was also not significantly different between the groups (p=0.29). Motor sparing blocks provide longer analgesia than patients receiving periarticular infiltration while not significantly reducing quadriceps muscle strength or increasing length of hospital stay

Introduction. At Sheffield Children's Hospital, treatment of leg length discrepancy is a common procedure. Historically, this has been done with external fixators. With the development in intramedullary technology, internal nails have become the preferred modality for long bone lengthening in the adolescent population. However, it is important to review whether this technology practically reduces the known challenges seen and if it brings any new issues. Therefore, the aim of this review is to retrospectively evaluate the therapeutic challenges of 16 fit-bone intramedullary femoral lengthening's at Sheffield Children's Hospital between 2021–2022. Materials & Methods. The international classification of function (ICF) framework was used to differentiate outcomes. The patient's therapy notes were retrospectively reviewed for themes around structural, activity and participation limitation. The findings were grouped for analysis and the main themes presented. Results. There were 8 males, mean age 17.4 years (range 17–18) and 8 females, mean age 15.9 years (range 14–18). 5 right and 11 left femurs were lengthened. Underlying pathology varied amongst the 16 patients. All patients went into a hinged knee brace post operatively. Structural limitations included: pain, fixed flexion deformity of the knee, loss of knee flexion, quadriceps muscle lag, muscle spasms and gluteal weakness. The primary activity limitation was reduced weight bearing with altered gait pattern. Participation limitations included reduced school attendance and involvement in activities with peers. Access to Physiotherapy from local services varied dramatically. Five of the cohort have completed treatment. Conclusions. Anecdotally, intramedullary femoral lengthening nails have perceived benefits for families compared to external fixators in the adolescent population. However, there remain musculoskeletal and psychosocial outcomes requiring therapeutic management throughout the lengthening process and beyond. Therefore, quantifying these outcomes is essential for measuring the impact on each patient for comparison. To interpret these themes, we need to evaluate the outcomes objectively, this was not done consistently in this review. Future research should look at outcome measures that are sensitive to all aspects of the ICF. With an aim of improving the therapeutic treatment provided and the overall outcome for the children treated

Aims. The aticularis genu (AG) is the least substantial and deepest muscle of the anterior compartment of the thigh and of uncertain significance. The aim of the study was to describe the anatomy of AG in cadaveric specimens, to characterize the relevance of AG in pathological distal femur specimens, and to correlate the anatomy and pathology with preoperative magnetic resonance imaging (MRI) of AG. Methods. In 24 cadaveric specimens, AG was identified, photographed, measured, and dissected including neurovascular supply. In all, 35 resected distal femur specimens were examined. AG was photographed and measured and its utility as a surgical margin examined. Preoperative MRIs of these cases were retrospectively analyzed and assessed and its utility assessed as an anterior soft tissue margin in surgery. In all cadaveric specimens, AG was identified as a substantial structure, deep and separate to vastus itermedius (VI) and separated by a clear fascial plane with a discrete neurovascular supply. Mean length of AG was 16.1 cm ( ± 1.6 cm) origin anterior aspect distal third femur and insertion into suprapatellar bursa. In 32 of 35 pathological specimens, AG was identified (mean length 12.8 cm ( ± 0.6 cm)). Where AG was used as anterior cover in pathological specimens all surgical margins were clear of disease. Of these cases, preoperative MRI identified AG in 34 of 35 cases (mean length 8.8 cm ( ± 0.4 cm)). Results. AG was best visualized with T1-weighted axial images providing sufficient cover in 25 cases confirmed by pathological findings.These results demonstrate AG as a discrete and substantial muscle of the anterior compartment of the thigh, deep to VI and useful in providing anterior soft tissue margin in distal femoral resection in bone tumours. Conclusion. Preoperative assessment of cover by AG may be useful in predicting cases where AG can be dissected, sparing the remaining quadriceps muscle, and therefore function. Cite this article: Bone Joint Open 2020;1-9:585–593

Introduction. Most of patients with unilateral hip disease shows muscle volume atrophy of pelvis and thigh in the affected side because of pain and disuse, resulting in reduced muscle weakness and limping. However, it is unclear how the muscle atrophy correlated with muscle strength in the patient with hip disorders. A previous study have demonstrated that the volume of the gluteus medius correlated with the muscle strength by volumetric measurement using 3 dimensional computed tomography (3D-CT) data, however, muscles influence each other during motions and there is no reports focusing on the relationship between some major muscles of pelvis and thigh including gluteus maximus, gluteus medius, iliopsoas and quadriceps and muscle strength in several hip and knee motions. Therefore, the purpose of the present study is to evaluate the relationship between muscle volumetric atrophy of major muscles of pelvis and thigh and muscle strength in flexion, extension and abduction of hip joints and extension of knee joint before surgery in patients with unilateral hip disease. Material and Methods. The subjects were 38 patients with unilateral hip osteoarthritis, who underwent hip joint surgery. They all underwent preoperative computed tomography (CT) for preoperative planning. There were 6 males and 32 females with average age 59.5 years old. Before surgery, isometric muscle strength in hip flexion, hip extension, hip abduction and knee extension were measured using a hand held dynamometer (µTas F-1, ANIMA Japan). Major muscles including gluteus maximus, gluteus medius, iliopsoas and quadriceps were automatically extracted from the preoperative CT using convolutional neural networks (CNN) and were corrected manually by the experienced surgeon. The muscle volumetric atrophy ratio was defined as the ratio of muscle volume of the affected side to that of the unaffected side. The muscle weakness ratio was defined as the ratio of muscle strength of the affected side to that of the unaffected side. The correlation coefficient between the muscle atrophy ratio and the muscle weakness ratio of each muscle were calculated. Results. The average muscle atrophy ratio was 84.5% (63.5%–108.2%) in gluteus maximus, 86.6% (65.5%–112.1%) in gluteus medius, 81.0% (22.1%–130.8%) in psoas major, and 91.0% (63.8%–127.0%) in quadriceps. The average muscle strength ratio was 71.5% (0%–137.5%) in hip flexion, 88.1% (18.8%–169.6%) in hip abduction, 78.6% (21.9%–130.1%) in hip extension and 84.3% (13.1%–122.8%) in knee extension. The correlation coefficient between the muscle atrophy and the ratio of each muscle strength between the affected and unaffected side were shown in Table 1. Conclusion. In conclusion, the muscle atrophy of gluteus medius muscle, psoas major muscle and quadriceps muscle significantly correlated with the muscle weakness in hip flexion. The muscle atrophy of psoas major muscle and quadriceps muscle also significantly correlated with the muscle weakness in knee extension. There were no significant correlation between the muscle atrophy and the muscle weakness in hip extension and abduction

Individuals with multi-compartment knee osteoarthritis (KOA) frequently experience challenges in activities of daily living (ADL) such as stair ambulation. The Levitation “Tri-Compartment Offloader” (TCO) knee brace was designed to reduce pain in individuals with multicompartment KOA. This brace uses novel spring technology to reduce tibiofemoral and patellofemoral forces via reduced quadriceps forces. Information on brace utility during stair ambulation is limited. This study evaluated the effect of the TCO during stair descent in patients with multicompartment KOA by assessing knee flexion moments (KFM), quadriceps activity and pain. Nine participants (6 male, age 61.4±8.1 yrs; BMI 30.4±4.0 kg/m2) were tested following informed consent. Participants had medial tibiofemoral and patellofemoral OA (Kellgren-Lawrence grades two to four) diagnosed by an orthopaedic surgeon. Joint kinetics and muscle activity were evaluated during stair descent to compare three bracing conditions: 1) without brace (OFF); 2) brace in low power (LOW); and 3) brace in high power (HIGH). The brace spring engages from 60° to 120° and 15° to 120° knee flexion in LOW and HIGH, respectively. Individual brace size and fit were adjusted by a trained researcher. Participants performed three trials of step-over-step stair descent for each bracing condition. Three-dimensional kinematics were acquired using an 8-camera motion capture system. Forty-one spherical reflective markers were attached to the skin (on each leg and pelvis segment) and 8 markers on the brace. Ground reaction forces and surface EMG from the vastus medialis (VM) and vastus lateralis (VL) were collected for the braced leg. Participants rated knee pain intensity performing the task following each bracing condition on a 10cm Visual Analog Scale ranging from “no pain” (0) to “worst imaginable pain” (100). Resultant brace and knee flexion angles and KFM were analysed during stair contact for the braced leg. The brace moment was determined using brace torque-angle curves and was subtracted from the calculated KFM. Resultant moments were normalized to bodyweight and height. Peak KFMs were calculated for the loading response (Peak1) and push-off (Peak2) phases of support. EMG signals were normalized and analysed during stair contact using wavelet analysis. Signal intensities were summed across wavelets and time to determine muscle power. Results were averaged across all 3 trials for each participant. Paired T-tests were used to determine differences between bracing conditions with a Bonferroni adjustment for multiple comparisons (α=0.025). Peak KFM was significantly lower compared to OFF with the brace worn in HIGH during the push-off phase (p Table 1: Average peak knee flexion moments, quadriceps muscle power and knee pain during stair descent in 3 brace conditions (n=9). Quadriceps activity, knee flexion moments and pain were significantly reduced with TCO brace wear during stair descent in KOA patients. These findings suggest that the TCO assists the quadriceps to reduce KFM and knee pain during stair descent. This is the first biomechanical evidence to support use of the TCO to reduce pain during an ADL that produces especially high knee forces and flexion moments. For any figures or tables, please contact the authors directly

We hypothesize that tethering adhesions of the quadriceps muscle are the major pathological structures responsible for a limited range of motion in the stiff arthritic knee. Forty-two modified quadriceps muscle releases were performed on 24 patients with advanced osteoarthritis scheduled for total knee arthroplasty. The ranges of motion were documented intraoperatively both before and immediately after the release. Passive flexion improved significantly in all patients (mean, 32.4 degrees of improvement, P < .001) following a modified quadriceps release, despite any presence of osteophytes or severe deformities. These results strongly implicate adhesions of the quadriceps muscle to the underlying femur, which prevent the distal excursion of the quadriceps tendon, as the restrictive pathology preventing deep flexion in patients with osteoarthritis

Introduction. A large number of total knee arthroplasty (TKA) patients, particularly in Japan, India and the Middle East, exhibit anatomy with substantial proximal tibial torsion. Alignment of the tibial components with the standard anterior-posterior (A-P) axis of the tibia can result in excessive external rotation of the tibial components with respect to femoral component alignment. This in turn influences patellofemoral (PF) mechanics and forces required by the extensor mechanism. The purpose of the current study was to determine if a rotating-platform (RP) TKA design with an anatomic patellar component reduced compromise to the patellar tendon, quadriceps muscles and PF mechanics when compared to a fixed-bearing (FB) design with a standard dome-shaped patellar component. Methods. A dynamic three-dimensional finite element model of the knee joint was developed and used to simulate a deep knee bend in a patient with excessive external tibial torsion (Figure 1). Detailed description of the model has been previously published [1]. The model included femur, tibia and patellar bones, TKA components, patellar ligament, quadriceps muscles, PF ligaments, and nine primary ligaments spanning the TF joint. The model was virtually implanted with two contemporary TKA designs; a FB design with domed patella, and a RP design with anatomic patella. The FB design was implanted in two different alignment conditions; alignment to the tibial A-P axis, and optimal alignment for bone coverage. Four different loading conditions (varying internal-external (I-E) torque and A-P force) were applied to the model to simulate physiological loads during a deep knee bend. Quadriceps muscle force, patellar tendon force, and PF and TF joint forces were compared between designs. Results. The RP design demonstrated consistently lower medial-lateral (M-L) force at the PF joint than the FB design, with greater differences between designs in later flexion once the patella was engaged in the sulcus groove; root-mean-square (RMS) differences in M-L force averaged 50 N less in the RP design throughout the flexion cycle, and 70 N less after 45° flexion (Figure 2). The FB design aligned for optimal bone coverage demonstrated 15% higher M-L forces than the FB design aligned with the tibial A-P axis. RMS load required by the quadriceps muscle was 60 N lower with the RP design than the FB design throughout the cycle (Figure 2). Discussion. Comparing a RP design with an anatomic patellar component and a FB design with a domed patellar component, the RP design demonstrated lower M-L PF joint and soft-tissue extensor mechanism forces. Differences were more pronounced under conditions of high I-E torque where the RP design accommodated large relative TF rotation. Differences in FB alignment resulted in substantially different PF M-L forces; when the FB component was mal-aligned with respect to the tibial A-P axis (and the line-of-action of the patellar tendon) the resulting M-L PF force was increased. The RP design reduced the demands on the extensor mechanism and loads on the PF joint and facilitated better coverage of the resected tibial bone surface

Purpose of the study: Congenital dislocation of the patella is a very rare condition. The pathology is inconsistent and treatment modalities are unclear. The aim of the study was to show the results of operative treatment of congenital dislocation of the patella. Material and methods: 9 knee joints in 7 patients with congenital dislocation of the patella have been treated between 1989 and 1999. Additional diagnoses were Rubinstein-Taybe syndrome, Larsen syndrome, pteryg-ium syndrome and cerebral palsy in 1 patient each. The age at the time of surgery was 8.9 years on average (between 4.3 and 14.8 years). In 6 knees primary treatment was a medial shifting of the quadriceps muscle according to Stanisavljevic, in the other 3 a combination of lateral release according to Green, proximal quadriceps realignment according to Insall and either medial displacement of the tibial tuberosity according to Elmslie or a duplication of the patellar tendon according to Goldthwait had been done. Results: The follow-up time was 6.4 years on average (between 2 and 12.5 years). 4 of 9 patellae remained stable after 1 operation, 3 remained stable after 2 operations and 2 remained unstable. 4 of the 9 knees were symptomatic at the time of follow-up. All patients were able to walk and to run and all had full extension. Apart from recurrence there were no major complications. Conclusions: Permanent dislocation of the patella reduces the extension force of the quadriceps muscle significantly. Medial shifting of the quadriceps muscle according to Stanisavljevic gives the best chance to reduce the patella permanently. Postoperative taping, splinting and muscle-exercises are often necessary to get a stable situation

BIONs (Bionic Neurons) are microminiature stimulators that can be injected into muscles. They receive power and commands from an external magnetic field. They have been shown to be safe and effective for stimulating muscles in animals. Clinical trials are underway to assess the efficacy and safety of BIONs for therapeutic exercise of weak or paralyzed muscles. In patients with knee osteoarthritis weakness of quadriceps muscle has been shown by different authors to be highly correlated with pain and functional impairment, while quadriceps strengthening is associated with significant improvements of clinical scores. Preliminary results of the use of BIONs to strengthen the quadriceps muscles in patients affected by knee osteoarthritis are reported. Five patients have been recruited so far, three of them have completed the protocol. Patients are implanted with BIONs near the common femoral nerve and in the vastus medialis muscle, and stimulated for 12 weeks. Therapy starts three days after implantation with two-three stimulation sessions of 10–30 minutes each day. Stimulation parameters are intended to recruit the quadriceps muscles (up to 10 X threshold for muscle twitch) at relatively low frequencies (5–13 pps) in short trains (5–10 s) with pauses between trains (5 s). Outcome measures include WOMAC, Knee Society Score, muscle measurements with MRI, gait analysis, isokinetic tests. All patients found muscle stimulation to be agreeable. No adverse events or complications have been observed. Thresholds for eliciting muscle contractions remained stable over time. In the three patients knee function improved and pain decreased over the stimulation period, while muscle thickness, as measured by MRI, increased. Results are preliminary but encouraging. We anticipate studying 15 patients to demonstrate clearly the safety and efficacy of this technology in this application. Plans are underway for additional clinical trials in orthopaedic patients as well as in stroke patients

Introduction. Patients undergoing a total knee arthroplasty (TKA) are now living longer and partaking in more active lifestyles. They expect a high level of post-operative function and long term durability of their implant. Using electromyography (EMG) analysis helps further explain biomechanical findings by giving insight as to what is occurring at the level of the muscles. Normal biomechanics are not restored post-TKA as patients have reduced knee flexion and weakened quadriceps muscles compared to their healthy peers. Purpose. The purpose of this study was to compare muscle activation in TKA patients who received a medial pivot (MP) or posterior stabilized (PS) implant to those of healthy controls (CTRL) during a stair ascent task. Methods. A total of 12 patients were assigned to either a MP or PS TKA operated by the same surgeon. Approximately 9 months following surgery, the 12 patients along with 6 CTRL patients completed an EMG analysis during a stair ascent task (Table 1). Wireless EMG electrodes were placed on 4 muscles: vastus medialis (VM), vastus lateralis (VL), biceps femoris long head (BF), and semimembranosus (SM) muscles. All participants completed maximal voluntary contractions (MVICs) during knee flexion and extension while seated with the knee flexed at 60°. Following the MVICs, participants completed 5 trials of a 3-step stair ascent task. TKA patients were instructed to make the first step onto the staircase with their operated limb. EMG data were processed in Matlab. Peak muscle activity (PeakLE EMG) and total muscle activity (iEMG) from each muscle was obtained during stance phase. Data were averaged between left and right limbs for the CTRL group and compared to the operated limb of TKA groups. Non-parametric Kruskal Wallace ANOVA tests were used to test for statistical significance between groups and Wilcoxon rank sum tests were used to identify differences with α=0.05. Results. Both TKA groups had significantly greater PeakLE EMG of the quadriceps muscles compared to the CTRL group (Figure 1). PeakLE EMG of the BF and VM muscles were significantly greater in the PS group compared to both CTRL and MP groups. The PS group had significantly greater iEMG of the BF, VL and VM muscles compared to the CTRL group (Figure 2) whereas the PS group had significantly greater iEMG of the SM and VM muscles compared to the MP group. Conclusion. The MP group had lower PeakLE EMG for both VM and BF muscles compared to the PS group, indicating that the MP group activates these muscles less to achieve the stair ascent task. BF muscle stabilizes the knee roll-back motion while the VM muscle extends the leg to clear the steps. iEMG for the VM and BF muscles were greater for the PS group indicating that they have to activate their muscles longer and to a greater extent in order to stabilize the joint. This increased stability in MP implants is achieved through the concave aspect on the medial tibial plateau for the femoral condyle to pivot in. This will reduce implant wear, prolonging implant longevity

Introduction. The purpose of this study was to determine whether the patient's perceived outcome and speed of recovery differs between a posterior cruciate ligament (PCL) substituting (cam-post type) and PCL sacrificing (ultracongruent polyethylene) total knee arthroplasty (TKA). Methods. Thirty eight patients (mean age, 65 years) underwent bilateral TKA using a PCL substituting and a PCL sacrificing prosthesis on each side. At each follow-up, the stability of anteroposterior and mediolateral laxity using stress radiographs, range of motion, quadriceps muscle power recovery using isokinetic dynamometer and radiographs were evaluated. At the 1-year evaluation, we asked, “Which is your better knee overall?” to determine the patients' preferences. Results. The mean varus/valgus laxities were 1.6Ë�/3.9Ë� in the PCL sacrificing side and 2.3Ë�/5.9Ë� in the PCL substituting side, and the mean anterior/posterior laxities were 6.4 mm/14.2 mm and 3.0 mm/7.3 mm at the 1-year follow up, respectively. Isokinetic peak torque at 60°/sec and 180°/sec in extension was 130% and 113% compared to the preoperative value in the PCL sacrificing side and 109% and 110% in the PCL substituting side, respectively. The differences in the posterior laxity and isokinetic peak torque at 60°/sec were significant statistically. Sixty-one percent preferred PCL sacrificing side to PCL substituting side. Conclusion. PCL sacrificing TKA showed more posterior laxity and better quadriceps muscle power at the time of short-term follow-up. Patients with bilateral TKA preferred PCL sacrificing TKA to PCL substituting TKA. Longer follow-up is needed to determine whether there will be an advantage in terms of longer-term function

Background: Paralysis of the crural nerve secondary to a compressive haematoma of the psoas in the pelvis is a well-known complication of anticoagulant therapy. This complication has also been described after hip or pelvic surgery. Its occurrence in a context of trauma is exceptional. Case report: A 16-year-old female adolescent sought emergency care for total deficit of knee extension. The patient had an enlarged painful knee subsequent to a skateboard fall. She reported knee trauma involving the patella and a direct shock to the homolateral hip, on the trochanter. Physical examination confirmed the knee and hip pain. Rest was advised. One and a half month after the accident, the patient again consulted for total deficit of active knee extension. The initial diagnosis suggested was posttraumatic rupture of the patellar tendon. An emergency MRI was normal, ruling out this diagnosis. More attentive physical examination revealed the presence of a complete paralysis of the quadriceps muscle by crural nerve palsy. MRI of the pelvic region revealed the presence of a voluminous haematoma of the psoas compressing the crural nerve. Emergency evacuation of the haematoma was performed. The patient underwent rehabilitation for one year and achieved progressive and complete recovery of the quadriceps function. An electromyogram obtained at one year was normal. Conclusion: This was an exceptional case of crural nerve palsy secondary to a posttraumatic haematoma of the psoas, with no notion of anticoagulation therapy. The initial knee injury was misinterpreted as involving a local patellar problem but in reality had caused a paralysis of the quadriceps muscle. MRI provided the diagnosis of psoas haematoma

Introduction: Patients with advanced osteoarthritis tend to have limited range of motion; the purpose of this in vivo anatomical study is to identify the anatomical structures responsible for limited knee movement in patient with osteoarthritis. Materials and Methods: 42 quadriceps releases were performed in patients who had TKA. The releases were carried out utilizing subvastus approach and just before proceeding with the knee replacement surgery. The ranges of motion were documented before and after the release using digital photography and lateral portable x-ray. No bony resection was done, and no ligament release was performed. Quadriceps excursion was also studied under fluoroscopy in six volunteers throughout the range of movement. Results: The quadriceps release improved the range of motion in all patients; at least 135 degrees of flexion were obtained. The average of improvement in knee flexion after the release was 36 degrees. The presence of osteophytes or gross deformity did not influence the degree of improvement. The fluoroscopy study has shown that the average excursion of quadriceps muscle from 0 to 145 degrees is 7 cm. The excursion per degree varies throughout the range of motion; it is more per degree near full flexion and extension than around 90 degree of flexion. Conclusion: The limited excursion of the quadriceps muscle is the main limiting factor to knee flexion. Other pathological changes such as osteophytes, surface pathology, posterior capsule and the cruciate ligaments play very limited roles

Patients with advanced osteoarthritis tend to have limited range of motion; the purpose of this in vivo anatomical study is to identify the anatomical structures responsible for limited knee movement in patients with osteoarthritis. Forty-two quadriceps releases were performed in patients who had TKA. The releases were carried out utilising subvastus approach and just before proceeding with the knee replacement surgery. The ranges of motion were documented before and after the release using digital photography and lateral portable X-ray. No bony resection was done, and no ligament release was performed. Quadriceps excursion was also studied under fluoroscopy in six volunteers throughout the range of movement. The quadriceps release improved the range of motion in all patients; at least 135 degrees of flexion were obtained. The improvements were more dramatic in patients who had previous surgeries. The average of improvement in knee flexion after the release was 36 degrees. The presence of osteophytes or gross deformity did not influence the degree of improvement. The fluoroscopy study has shown that the average excursion of quadriceps muscle from 0 to 145 degrees is 7 cm. The excursion per degree varies throughout the range of motion; it is more per degree near full flexion and extension than around 90 degrees of flexion. The limited excursion of the quadriceps muscle is the main limiting factor to full knee flexion. Other pathological changes such as osteophytes, surface pathology, posterior capsule and the cruciate ligaments play very limited roles

Disuse atrophy is the basis for profound physiological changes of the muscles of immobilised limbs. The aim of this study was to use ultrasound to assess the quadriceps musculature and to try and measure atrophy. We monitored the effects of enforced reduction of mobility due to trauma on the intramuscular architecture of the quadriceps using high resolution real-time ultrasonography (HRRTU) in 13 skeletally mature male patients (43.2 years, range 16 to 82 years), with an isolated unilateral diaphyseal fracture of the femur or of the tibia. All patients had undergone interlocked intramedullary nailing (IIN). Using HRRTU, the pennation angles and muscle fibre lengths of vastus lateralis, the cross sectional area (CSA) of the rectus femoris, and the quadriceps muscle layer thickness (MLT) were measured in the injured and the normal contralateral limb. Repeated measurements showed the technique of measurement of the variables used in this study to be highly reproducible. There was a significant difference in the angle of pennation of the vastus lateralis in the nailed (15.4°) and the unnailed limb (21.2°), documenting that muscle atrophy causes a change to muscle architecture that results in a significant decrease in pennation angle (p = 0.0002). The muscle fibre length was significantly different (p=0.002) and there was a significant correlation between pennation angle and muscle fibre length (r=−0.51, p=0.001). There was also a significant difference in the quadriceps MLT (p=0.001) and CSA of the rectus femoris (p=0.0004) implying that the whole of the quadriceps muscle is affected

Summary Statement. We observed that severe muscle weakness leads to OA, whereas a transient inflammatory stimulus did not have a significant effect on cartilage degradation. This arises the thought that a severe but transient inflammation may not be an independent risk factor for OA. Introduction. Biomechanical disturbances and joint inflammation are known risk factors, which may provoke or advance osteoarthritis (OA). However, the effect of interactions of such risk factors on the onset and progression of OA are still poorly understood. Therefore, the goal of this study was to investigate the in vivo effects of muscle weakness, joint inflammation, and the combination of these two risk factors, on the onset and progression of OA in the rabbit knee. Patients & Methods. Thirty 1-year-old skeletally mature female New Zealand White rabbits (weight: average 5.7kg, range 4.8–6.6kg) were used in this study. The animals were divided into four experimental groups: (i) surgical transection of the nerve branch of the common femoral nerve leading to the vastus lateralis muscle; (ii) muscle weakness of the quadriceps muscle induced by a chronic intramuscular injection of Botulinum toxin A (BTX-A) (3); (iii) intraarticular injection in the experimental knee joint with commercially available sterile Carrageenan solution to induce a transient severe inflammatory reaction (4); (iv) administration of both intraarticular injection of Carrageenan and intramuscular injection of BTX-A. In each animal, one hind limb was randomly assigned to the experimental intervention, while the contralateral side acted as its own control. Ninety days following intervention, muscle mass, joint diameter and cartilage histology of the femur, femoral groove, tibia and patella were assessed and microscopically analyzed using the OARSI histology score. Results. Transection of the femoral branch leading to the vastus lateralis as well as the administration of BTX-A led to a significant muscle mass loss for the vastus lateralis and the total quadriceps group, respectively. Similar results were seen in the combined Carrageenan/BTX-A group. There were no changes in total quadriceps muscle mass in the Carrageenan group. Knee joint diameters of the experimental limb were significantly increased in the Carrageenan and Carrageenan/BTX groups. VL transection and BTX-A injection did not cause significant increases in joint diameter. Histologic assessment of the cartilage showed that weakness of the vastus lateralis resulted in significantly higher OARSI scores in the patella and femoral groove, but not the tibiofemoral articulation. The administration of BTX-A caused significant cartilage damage in all 4 compartments (patella, femur, tibia, femoral groove). Intraarticular injection of Carrageenan did not cause significant cartilage damage in any compartment compared to the contralateral side. The combination of BTX-A and Carrageenan resulted in severe cartilage damage in the patella in all four compartments of the knee. The most severe damage was found on the medial side of the tibiofemoral joint and the lateral side of the patellofemoral joint. Conclusion. Severe muscle weakness over a three months period leads to the onset and progression of OA in the rabbit knee. A transient local inflammatory stimulus did not promote cartilage degradation, nor did it enhance cartilage degradation when it was combined with muscle weakness. This result is surprising and adds to the literature the idea that a severe but transient inflammation may not be an independent risk factor for OA

Objectives. Lower limb muscle power is thought to influence outcome following total knee replacement (TKR). Post-operative deficits in muscle strength are commonly reported, although not explained. We hypothesised that post-operative recovery of lower limb muscle power would be influenced by the number of satellite cells in the quadriceps muscle at time of surgery. . Methods. Biopsies were obtained from 29 patients undergoing TKR. Power output was assessed pre-operatively and at six and 26 weeks post-operatively with a Leg Extensor Power Rig and data were scaled for body weight. Satellite cell content was assessed in two separate analyses, the first cohort (n = 18) using immunohistochemistry and the second (n = 11) by a new quantitative polymerase chain reaction (q-PCR) protocol for Pax-7 (generic satellite cell marker) and Neural Cell Adhesion Molecule (NCAM; marker of activated cells). Results. A significant improvement in power output was observed post-operatively with a mean improvement of 19.7 W (95% confidence interval (CI) 14.43 to 30.07; p < 0.001) in the first cohort and 27.5 W (95% CI 13.2 to 41.9; p = 0.002) in the second. A strong correlation was noted between satellite cell number (immunohistochemistry) and improvement in patient power output (r = 0.64, p = 0.008). Strong correlation was also observed between the expression of Pax-7 and power output (r = 0.79, p = 0.004), and the expression of NCAM and power output (r = 0.84, p = 0.001). The generic marker explained 58% of the variation in power output, and the marker of activated cells 67%. Conclusions. Muscle satellite cell content may determine improvement in lower limb power generation (and thus function) following TKR

Background. Revision total knee arthroplasties (rTKA) are performed with increasing frequency due to the increasing numbers of primary arthroplasties, but very little is known regarding the influence of muscle strength impairments on functional limitations in this population. Objectives. The aim of this study was to assess relationship between muscle strength and functional level in patient with rTKA. Design and Methods. Twenty-three patients (8 males, 15 females) were included in the study with mean age 68.4±10 years. Patients performed 3 performance tests (50-Step Walking Test, 10 Meter Walk Test, 30-Second Chair-Stand Test), and one self-report test (HSS) were preferred to assess patients. The maximum isometric muscle strength of quadriceps femoris and hamstring muscles of all the patients was measured using Hand-Held Dynamometer (HHD). Results. While moderate-to-strong significant correlations was found between quadriceps femoris muscle strength and 30- Second Chair-Stand Test (r=0.390, p=0.049), 50-Step Walking Test (r=−0.530, p=0.005), 10 Meter Walk Test (r=−0.587, p=0.002), there were not significant correlation between HSS knee score and all performance-based tests (p>0.05). Also there were not significant correlation between hamstring muscle strength and all other measurement tests (p>0.05). Conclusion. The moderate-to-strong statistical significant correlation between quadriceps femoris muscle strength and functional performance tests suggests that improved postoperative quadriceps strengthening could be important to enhance the potential benefits of rTKA