Radiographic measurement of the congruence angle according to Merchant: validity, reproducibility, and limits.

PURPOSE: The objective of this study was to analyze the intra- and interobserver variability of this measurement according to a strict methodology and on a representative sample of the general population, as well as to identify the possible difficulties of measurement in case of patellar or trochlear dysplasia. METHODS: This observational study involved radiographic analysis by three independent observers of a total of 50 patients who had a loaded patellofemoral X-ray taken with the knee flexed to 45°. An initial reading was taken to measure the angle of the trochlear sulcus, the Merchant angle, and to classify the knees according to a possible trochlear dysplasia and/or patellar dysplasia according to Wiberg. A second measurement was then performed to analyze intraobserver agreement. Interobserver agreement was measured on all radiographic measurements (n = 100). RESULTS: The Merchant patellofemoral congruence angle showed good intraobserver concordance ranging from 0.925 (95% CI 0.868-0.957) to 0.942 (95% CI 0.898-0.967), as well as interobserver concordance ranging from 0.795 (95% CI 0.695-0.862) to 0.914 (95% CI 0.872-0.942). Poor results were found in terms of interobserver concordance on the measurement of the Merchant angle in case of stage 3 Wiberg patella ranging from 0.282 (95% CI -0.920 to 0.731) to 0.611 (95% CI 0.226-0.892). CONCLUSION: Congruence angle is one of most commonly used measurements for patellar tracking. However, the convexity of the patellar surface makes it difficult to identify the patellar apex on its intraarticular facet, making the measurement of the Merchant congruence angle unreliable and not very reproducible in cases of stage 3 Wiberg patella. Registration N°IRB 2021/139.

Extrusion and meniscal mobility evaluation in case of ramp lesion injury: a biomechanical feasibility study by 7T magnetic resonance imaging and digital volume correlation.

Introduction: The existing body of literature on the biomechanical implications of ramp lesions is limited, leaving a significant gap in our understanding of how these lesions impact joint kinematics and loading in the medial compartment. This cadaveric biomechanical study aims to address this gap by employing an innovative Digital Volume Correlation (DVC) method, utilizing 7 Tesla Magnetic Resonance Imaging (MRI) images under various loading conditions. The primary objective is to conduct a comprehensive comparison of medial meniscal mobility between native knees and knees affected by grade 4 ramp lesions. By focusing on the intricate dynamics of meniscal mobility and extrusion, this work seeks to contribute valuable insights into the biomechanical consequences of medial meniscus ramp lesions. Materials and methods: An initial set of 7T MRI imaging sessions was conducted on two intact native knees, applying load values up to 1500N. Subsequently, a second series of images was captured on these identical knees, with the same loads applied, following the creation through arthroscopy of medial meniscus ramp lesions. The application of DVC enabled the precise determination of the three components of displacement and spatial variations in the medial menisci, both with and without ramp lesions. Results: The measured directional displacements between native knees and injured knees indicate that, following the application of axial compression load, menisci exhibit increased extrusion and posterior mobility as observed through DVC. Discussion: Injuries associated with Subtype 4 medial meniscus ramp lesions appear to elevate meniscal extrusion and posterior mobility during axial compression in the anterior cruciate ligament of intact knees. Following these preliminary results, we plan to expand our experimental approach to encompass individuals undergoing weight-bearing MRI. This expansion aims to identify meniscocapsular and/or meniscotibial insufficiency or rupture in patients, enabling us to proactively reduce the risk of osteoarthritic progression.

Study of Mechanical Behavior in Epiphyseal Fracture Treated by Reduction and Cement Injection: No Immediate Post-Operative Weight-Bearing but Only Passive and Active Mobilization Should be Advised.

The development of new percutaneous treatment techniques using a balloon for the reduction and cement for the stabilization for tibial plateau fractures (TPF) are promising. The biomechanical changes brought by the cement in the periarticular fracture are unknown. The objective of this study was to provide elements of understanding of the bone behavior in an epiphyseal fracture treated with cementoplasty and to define the modifications brought about by the presence of this cement in the bone from both an architectural and biomechanical point of view. In vitro animal experimentation was conducted. Bones samples were prepared with a cavity created with or without cancellous compaction, aided by balloon expansion following the same protocol as in the treatment of TPF. A uniaxial compression test was performed with various speeds and by using Heaviside Digital Image Correlation to measure mechanical fields. Preliminary finite element models were constructed with various boundary conditions to be compared to our experimental results. The analysis of the images permits us to obtain a representative load vs. time response, the displacement fields, and the strain distribution for crack initiation for each sample. Microcracks and discontinuity began very early at the interface bone/cement. Even when the global behavior was linear, microcracks already happened. There was no strain inside the cement. The finite element model that matched our experiments had no link between the two materials. In this work, the use of a novel correlation process highlighted the biomechanical role of the cement inside the bone. This demonstrated that there is no load transfer between bone and cement. After the surgery, the cement behaves like a rigid body inside the cancellous bone (same as a screw or plate). The cement provides good reduction and primary stabilization (mini-invasive approach and good stress distribution), permitting the patient to undergo rehabilitation with active and passive mobilization, but no weight-bearing should be authorized while the cortical bone is not consolidated or stabilized.

Varus malalignment of the lower limb increases the risk of femoral neck fracture: A biomechanical study using a finite element method.

INTRODUCTION: The understanding of the stresses and strains and their dependence on loading direction caused by an axial deformity is very important for understanding the mechanism of femural neck fractures. The hypothesis of this study is that lower limb malalignment is correlated with a substantial stress variation on the upper end of the femur. The purpose of this biomechanical trial using the finite element method is to determine the effect of the loading direction on the proximal femur regarding the malalignment of the lower limb, and also enlighten the relation between the lower limb alignment and the risk of a femoral neck fracture. METHODS: Ten segmentations of CT scans were considered. An axial compression load was applied to the femoral head to digitally simulate the physiological configuration in neutral position as well as in different axial positions in varus/valgus alignment. RESULTS: The stress at the proximal femur changes as the varus _valgus angle does. It can be observed the smaller absolute stress at angle 10° (valgus) and the higher absolute stress at angle -10° (varus). The mean maximum von Mises stress value was 14.1 (SD=±3.48) MPa for 0°, while the mean maximum von Mises stress value was 17.96 MPa (SD=4.87) for -10° in varus. The fracture risk indicator of the proximal femoral epiphyses changes inversely with angle direction. The FRI was the highest at -10° and the lowest at 10°. CONCLUSION: Based on the biomechanical findings and the fracture risk indicator determined in this preliminary study, varus malalignment increases the risk of femoral neck fracture. Consideration of other parameters such as bone mineral density and morphological parameters should also help to plan preventive medical strategy in the elderly.

Contribution of Minimally Invasive Bone Augmentation With PMMA Cement in Primary Fixation of Schatzker Type II Tibial Plateau Fractures.

Background: The most common type of fracture of the lateral tibial plateau is the Schatzker type II split-depressed fracture. Minimally invasive surgery using balloon reduction appears to be very promising compared to the gold standard using a bone tamp. This surgery aims to have the best reduction and stabilization to benefit from an early passive and active rehabilitation to avoid stiffening and muscle wasting. Using a balloon for fracture reduction has allowed the use of semi-liquid Injectable Bone Cement (IBC) fillers. These fillers can be phosphocalcic or polymethyl methacrylate (PMMA). The latest recommendations on these IBCs in spinal surgery increasingly rule out phosphocalcic fillers because of their low mechanical strength. Questions/purposes: 1) What is the mechanical influence of IBC filling (PMMA) regarding the split and depression components of a Schatzker type II fracture? 2) What is the mechanical influence of osteosynthesis regarding the split and depression components of a Schatzker type II fracture with or without PMMA filing in three different kinds of percutaneous fixations? Methods: This biomechanical study was performed on 36 fresh frozen tibia/fibula specimens. Six groups were formed according to the type of percutaneous osteosynthesis or possible PMMA filling. Mechanical strength tests were carried out using a Unicompartmental Knee prosthesis and displacement components were measured on either side of the separation on the anterolateral facet by optical method. Results: We found a significant difference between cementless and cemented osteosynthesis for depression fracture stabilization (difference -507.56N with 95% confidence interval [-904.17; -110.94] (p-value = 0.026)). The differences between the different types of osteosynthesis were not significant (p-value = 0.58). There was a significant difference between osteosynthesis without cement and osteosynthesis with cement on separation (difference -477.72N [-878.52; -76.93] (p-value = 0.03)). The differences between the different types of fixations were not significant regarding separation (p-value = 0.99). Conclusion: PMMA cement significantly improves primary stability, regardless of the type of osteosynthesis for a Schatzker type II plateau fracture. Filling with PMMA cement during tuberoplasty seems to be a very promising strategy in association with percutaneous osteosynthesis to allow rapid recovery after surgery.

Experimental validation of a new technique for the assessment of posterior tibial translation (ABC angle) after posterior cruciate ligament rupture.

BACKGROUND: The aim of this cadaver study was to evaluate an original technique for measuring posterior tibial translation based on an angle value instead of a distance value, with and without posterior stress application. It was hypothesized that an angle measurement of the posterior tibial translation would confirm the presence of a PCL tear with the knee flexed and completely extended. METHOD: Using fresh cadavers, a set of strict lateral views were taken by fluoroscopy with the knee at 0°, 45° and 90° flexion on the intact knee and after transecting the PCL. The primary endpoint was the change in the posterior translation measured using a new technique, the ABC angle. This measurement was compared to the conventional posterior translation distance measurement with and without a posterior stress placed on the knee. RESULTS: Application of a posterior stress revealed clear changes in posterior translation after PCL transection with the knee at 0° for the angle technique and at 45° and 90° for the two techniques (p < 0.05). Contrary to the reference method, the ABC angle method found a statistically significant difference in posterior translation with the knee in extension. CONCLUSION: Our technique provides a reliable radiographic measurement of posterior translation with the knee in extension, which should make it easier to acquire radiographs in patients who have pain with knee flexion. This angular measurement also has the advantage of not needing length calibration contrary to the reference technique. LEVEL OF EVIDENCE: IV.

Aseptic osteonecrosis of the femoral head in patients with sickle cell anemia.

Sickle cell disease (SCD) is a genetic trouble of the hemoglobin synthesis inherited as an autosomal recessive trait, whose prevalence can vary from 5 to 25% in the different parts of the world. It is characterized by the presence of abnormal hemoglobin HbS instead of hemoglobin A. Patients suffering from major forms of SCD present the risk of developing epiphyseal necrosis. Aseptic osteonecrosis of the femoral head (AOFH) caused by ischemia, or bone infarction can affect between 20 and 50% of SCD patients. The femoral head is the most frequent epiphyseal location with a range of 74.6%. AOFH can affect patients at any age, but is mainly detected in men under 50 years. Indeed, a large majority of cases, in a range of 60%, have been diagnosed at an early radiological stage in young adults whose average age varies, in the literature, between 27 and 36 years. A surgical procedure becomes sometimes necessary due to the severity of pain and the functional consequences, frequently following the mechanical collapse of the osteonecrosis area. It is estimated that approximately 25-30% of SCD patients will undergo a total hip arthroplasty before 50y. Although the mortality rate, between 0.2-2.6%, tends to be similar to the general population rate undergoing a prosthetic surgery, the perioperative complications vary from 11.5 to 67%. Here, we clarify the epidemiological data and present an exhaustive update on the different preventive and therapeutic strategies, as well as the perioperative management in patients with an AOFH caused by SCD and risking multiple complications.

Medial closing-wedge distal femoral varus osteotomy: Symptoms and functional impact in cases of associated patellofemoral osteoarthritis. A two-year follow-up prospective pilot study.

PURPOSE: To date, indications for distal femoral varus osteotomy (FVO) in cases of associated patellofemoral osteoarthritis (PFO) have yet to be clarified. The purpose of this prospective study is to assess the short-term symptoms, functional and radiological impact of a medial closing-wedge femoral varus osteotomy on the patellofemoral joint in patients with valgus deformities who are afflicted with lateral tibiofemoral osteoarthritis (LTFO) associated with PFO. METHODS: Fourteen patients (15 knees) received a medial closing-wedge femoral varus osteotomy. The functional impact of an FVO on the patellofemoral joint was assessed based on the KOOS-PF (Knee Injury and Osteoarthritis Outcome Score-Patellofemoral Subscale), the Kujala score and the patellofemoral symptoms. Realignment of the patella was measured by the Merchant's patellofemoral congruence angle. The pre- and post-operative symptoms and functional scores were compiled prospectively and compared two years after the surgery. RESULTS: The Kujala patellofemoral functional scores and the KOOS-PF showed considerable improvement with a differential of +37.5 points ± 20.4 and +42.7 points ± 19.3 (p < .01) respectively. The average Merchant's congruence angle went from 8.8° laterally to 3.6° medially, resulting in medialization of the patella, with a significant difference (p < .01). Based on the specific clinical analysis of the patellar joint, preoperative J-sign was identified in 26.7% of patients (n = 4) and was not found during postoperative examination (p = .1). Preoperative apprehension test was identified in 33.3% of patients (n = 5) against 13.3% (n = 2) after surgery (p = .39). Preoperative pain extension test was identified in 40% of patients (n = 6) against 20% during postoperative clinical analysis (p = .43). DISCUSSION: Although the threshold of significance for patellofemoral symptoms was not reached, the medial closing-wedge femoral varus osteotomy induces a significant medialization of the patella (Merchant's congruence angle) and improves short-term functional results even with co-existing patellofemoral osteoarthritis. Due to the lack of specificity of the patellofemoral scores, patellofemoral osteoarthritis improvement is difficult to determine on its own, but does not represent a contraindication to FVO. LEVEL OF EVIDENCE: III. Prospective clinical study.

Reverdin-Isham procedure for mild or moderate hallux valgus: clinical and radiographic outcomes.

BACKGROUND: In the last decade, interests in minimal incision surgery have been growing. Theoretically, this kind of procedure could decrease time to recovery and rehabilitation, with a reduction in morbidity. The present study assessed clinical and radiological outcomes and complications of percutaneous surgery for mild-to-moderate hallux valgus using Reverdin-Isham and Akin osteotomies without fixation after 60 months of follow-up. METHODS: A series of 48 patients (57 cases) with medium-to-moderate hallux valgus underwent the same percutaneous surgery, between 2003 and 2011. Data collection involved preoperative dorsal flexion, plantar flexion, M1P1, M1M2, DMAA angles, AOFAS scale score, and subjective satisfaction. RESULTS: AOFAS scale score rose from a preoperative median of 55.9-89.2/100 postoperatively (p < 0.001); 51 surgical procedures (89.5%) were considered as satisfactory or very satisfactory by patients at the end of follow-up. Hallux valgus and distal metatarsal articular angle (DMAA) were significantly reduced (29.3° and 14.1°-15.4° and 7.7°, p < 0.001, respectively). There was a significant increase in MTPJ 1 stiffness (p < 0.001). DISCUSSION: Percutaneous correction by Reverdin-Isham and Akin osteotomies seems to be effective in isolated medium-to-moderate hallux valgus. Stiffness observed is comparable to other percutaneous and open procedures but needs to be compared in a randomized controlled clinical trial to extra-articular percutaneous procedures without capsule detachment in association with an internal fixation which allows an early mobilization. LEVEL OF CLINICAL EVIDENCE: IV.

Case Report: Bothrops lanceolatus Snakebite Surgical Management-Relevance of Fasciotomy.

Bothrops lanceolatus is an endemic Crotalidae species in Martinique, where approximately 30 cases of envenoming are managed yearly. Envenoming characteristics from Bothrops species include local tissue damage, systemic bleeding, and hemodynamic alterations. We hereby report a case of severe envenomation following B. lanceolatus snakebite to the right calf. Severe local manifestations developed progressively up to the lower limb despite adequate antivenom therapy. Systemic manifestations of venom also occurred, resulting in intensive care therapy. Surgery exploration revealed soft tissue necrosis, friability of the deep fascia, and myonecrosis. The patient needed multiple debridement procedures and fasciotomy of all leg compartments and anterior compartment of the thigh. Diagnosis of necrotizing fasciitis was confirmed by positive Aeromonas hydrophila blood cultures. This clinical case illustrates that major soft tissue infection, including necrotizing fasciitis may occur after snakebite. Abnormal coagulation tests should not delay surgical management, as severe envenoming is a life-threatening condition.

Postoperative infections after limb-sparing surgery for primary bone tumors of the pelvis: Incidence, characterization and functional impact.

INTRODUCTION: Surgical site infections (SSI) represent the most common postoperative complication after limb sparing surgery for primary malignant bone tumors, with incidence ranging from 10 to 47%. There is no consensus concerning about the optimal surgical strategy, or the adequate antibiotic prophylaxis in pelvic resections. A greater knowledge of these infections and their surgical trajectories seem essential to obtain. MATERIALS AND METHODS: We retrospectively studied 45 cases of pelvic resection, including at least the periacetabular zone 2 of Enneking, performed between 1989 and 2013 in the same center. Infection rate, risk factors and surgical trajectories were analyzed. The impact of a postoperative infection on the quality of life and functional recovery was evaluated by the Musculoskeletal Tumor Society scoring system (MSTS). RESULTS: Sixteen patients presented a SSI in the first post-operative year (35.6%). We found as risk factors the pre-operative ASA score, the age at surgery and the number of packed red cells transfused during surgery. In case of failure of an initial washout, an iterative procedure is responsible for a high failure rate of 88.9%. Irrespective of the type of reconstruction, our functional results show that this surgery is often a source of handicap with a MSTS score of 13.77 in infected patients versus 17.70 in non-infected patients, at two-year follow-up. DISCUSSION: In case of failure of an initial wash, prosthetic material must be removed and a hip transposition procedure should be preferred to a second-look surgery. Concerning prophylactic antibiotherapy, a dual therapy for at least 48 h after surgery should probably be preferred.

Arthroscopic suture repair of acute quadriceps tendon ruptures.

Acute quadriceps tendon ruptures disrupt the continuity of the extensor mechanism and must be treated surgically. Tendon reattachment with suture anchors has recently been shown to be biomechanically superior to reattachment through transosseous tunnels. In this context, arthroscopy is an interesting alternative. It can limit postoperative wound healing and infectious complications, while ensuring functional outcomes that are equivalent to standard techniques. The goal of this technical note is to describe an original, reproducible method for arthroscopic reattachment of the quadriceps tendon with suture anchors. Four patients were operated using this technique in a pilot study. No wound healing, infectious complications or re-tears were observed. At 6 months' postoperative, the mean subjective IKDC score was 85.8/100.

ACL reconstruction in 11 children using the Clocheville surgical technique: Objective and subjective evaluation.

INTRODUCTION: The over-the-top position of the femoral metaphyseal tunnel during extraphyseal ligament reconstruction of the anterior cruciate ligament (ACL) according to Clocheville may be responsible for negative anisometry. Until now, the follow-up of children operated using this pediatric technique was limited to screening for iatrogenic epiphysiodesis and the search for postoperative clinical instability. The objective of this study was to measure residual laxity using objective tests, to quantify muscle recovery, and to evaluate the quality of life of these patients in terms of the sports activities. MATERIAL AND METHODS: Eleven patients with a mean age of 13.5years were seen at a mean 2.1years of follow-up. They underwent objective clinical tests (GNRB(®) arthrometer and CON-TREX(®) dynamometer) as well as subjective questionnaires (IKDC and KOOS). RESULTS: No significant difference was found between the healthy knee and the operated knee for either the GNRB(®) at 134N (P=0.79) or at 200N (P=0.98). The CON-TREX(®) system allowed us to measure a median percentage of quadriceps recovery of 80.7% (range, 52.2-114.5) in terms of muscle power (60°/s) and 81.2% (range, 51.6-109.6) for muscle response (180°/s). The median subjective IKDC score was 94.73/100 (range, 73.68-98.93); 72.7% of the patients resumed competitive sports. DISCUSSION: This study's lack of statistical power did not show a significant difference in terms of residual laxity at rest of GNRB(®) transplants, while a mean differential of +0.4mm was observed. Although pediatric transphyseal ligament reconstruction techniques are increasingly used, the Clocheville technique remains, in our opinion, an attractive surgical alternative in the youngest subjects, with no major risk of iatrogenic epiphysiodesis even though it is theoretically anisometric. LEVEL OF EVIDENCE: IV.