Semimembranosus Tendon Findings in Acute Anterior Cruciate Ligament Tears: MRI Evaluation and Associated Lesions.

BACKGROUND: The semimembranosus (SM) tendon acts as a secondary dynamic stabilizer of the knee. It restrains external rotation and anterior translation of the medial compartment. Its role in the mechanism of injury during anterior cruciate ligament (ACL) rupture is unknown. HYPOTHESIS: The bone bruise (BB) often detected at the posteromedial tibia in association with acute ACL tear may be related to the traction force from the SM tendon insertion. Magnetic resonance imaging (MRI) alterations can be detectable at the direct arm of the SM tendon in association with acute ACL injury. STUDY DESIGN: Cross-sectional study: Level of evidence, 3. METHODS: In the first study phase, 36 noninjured patients underwent knee MRI. The anatomic appearance of the SM tendon was evaluated. An imaging score for evaluating the SM tendon was developed for the purpose of the study. The intensity (in the axial or sagittal plane), morphology, and thickness of the distal SM tendon was evaluated and scored (4 total points). In the second study phase, 52 patients undergoing acute ACL reconstruction were included. Preoperative MRI was examined and scored, with documentation of BB at the posteromedial tibial plateau. Finally, arthroscopic diagnosis of a ramp lesion was confirmed. Logistic regression analysis was carried out for correlation between an altered MRI scoring system and the presence of BB at the posteromedial tibial plateau, the presence of a ramp lesion, or both. RESULTS: Interrater agreement of 100% was obtained in the noninjured cohort (ie, no alteration found in any patient). The score validation in the cohort of patients with acute ACL injury showed a Cohen κ of 0.78 (interrater agreement, 82.7%). The direct arm of the SM tendon was altered in 35 of 52 patients (67.3%). A ramp lesion of the medial meniscus was arthroscopically detected in 21 patients (40.4%). The presence of BB at the posteromedial tibial plateau was detected in 33 patients (63.5%) and at the posterior medial femoral condyle in 1 (1.9%). Correlation analysis showed a significant association of a pathologic SM score with the presence of BB at the posteromedial tibial plateau (odds ratio = 2.7; P = .001). Conversely, no correlation was observed between the pathologic score and the presence of a ramp lesion (odds ratio = 0.88; P = .578). CONCLUSION: The prevalence of pathologic findings in the direct arm of the SM tendon insertion was high in the acutely injured cohort with ACL rupture and is correlated with the presence of BB at the posteromedial tibial plateau. The main hypothesis formulated for the study was confirmed.

The post-traumatic meniscal extrusion, sign of meniscotibial ligament injury. A case series.

BACKGROUND: Medial meniscal extrusion (ME) has been found to be associated to anterior cruciate ligament (ACL) injury. Post-traumatic extrusion is mainly attributed to meniscotibial ligament (MTL) tear. The aim of this retrospective study was to assess the incidence of MTL tear associated with meniscal extrusion, evaluate arthroscopic findings and the associated clinical findings. HYPOTHESIS: The medial meniscal extrusion, when associated to ACL injury, is related to a tear of the MTL. PATIENTS AND METHODS: Patients who underwent to primary or revision ACL reconstruction with associated medial meniscal rise and/or meniscotibial tear or insufficiency were retrospectively identified over a 5-year period (from 2015 to 2019). Twenty-four patients were included in this study with preoperative magnetic resonance imaging (MRI) carried out at our institution Each MRI was evaluated by the senior author for the presence of meniscal extrusion and also for the additional pathology of meniscotibial ligament. Patient medical records were reviewed to obtain demographic information, including age, gender, and arthrometric evaluation of anteroposterior laxity. RESULTS: All included patients underwent arthroscopic ACL reconstruction using autograft tissue, (19 primary and in 5 revision ACL reconstruction). The mean age was 31.2 years (range: 15-57; SD: 12.3 years) at the time of surgery. ME was identified at MRI in all cases preoperatively and confirmed arthroscopically. No correlation was found between meniscal extrusion and anteroposterior translation (ρ=-0.270; p=0.202). Neither between having more than 3mm of extrusion and gender (χ2=0.80; p=0.371), acute/chronic lesion (χ2=0.91; p=0.341) and primary/revision reconstructions (χ2=0.83; p=0.364). In the last three patients, arthroscopic treatment of meniscal extrusion was carried out through outside-in repair of medial meniscus at its capsular junction. Reduction of meniscal extrusion has been verified by MRI, performed at 3-month follow-up. DISCUSSION: A high prevalence of ME was found at MRI in patients with ACL injury and MTL tear. Therefore, ME may be associated to acute or chronic ligamentous injury involving the MTL, and its tear can be considered as the main determinant of extrusion. Further research is needed to increase evidence concerning MTL incidence and surgical outcomes. LEVEL OF EVIDENCE: IV, retrospective case series.

Anomalous insertion of anterior and posterior horns of medial meniscus. Case report.

BACKGROUND: Anatomical variations of the attachment of medial meniscus are a common finding. However, anomalies of the posterior horn are extremely rare. Only two cases of posterior root anomaly have been described prior to the routine use of arthroscopy for evaluation and treatment of meniscal pathology. In this report, we present an anomaly of both the anterior and posterior roots of the medial meniscus that posed both a diagnostic and therapeutic dilemma. CASE PRESENTATION: The patient is young male soccer player who is currently 16 years of age and began having the atraumatic onset of pain and symptoms that limited performance starting at age 14 and was referred for failure of response to nonoperative treatment. Diagnostic arthroscopy revealed the presence of an anteromedial meniscofemoral ligament whereas the posterior root showed no bony attachment. The radiographic and arthroscopic findings are described. The clinical decision was made after to proceed with observation, reassurance, and gradual return to full activity with physiotherapy guidance. DISCUSSION AND CONCLUSION: The absence of injury, the mild complaints reported by the patient, his age, skeletal immaturity, and remaining growth led us to adopt a conservative approach to treating this anatomic variant and currently the patient is able to participate fully in sports without symptoms or restrictions.

MI-Environment: Geospatial patterns and inequality of relative heat stress vulnerability in Michigan.

Heat stress causes morbidity and mortality and is increasing with climate change. Heat stress can pose particular challenges in northern regions not well adapted to heat. To assist decision makers, we identified the relative vulnerability of census tracts within Michigan to factors that increase exposure to heat stress or reflect susceptibilities in the population based on a California heat vulnerability index. In the MI-Environment assessment, we used a Geographic Information System (GIS) to combine future ensemble climate model projections to create a total of 9 geospatial and demographic variables. As part of a broader planned cumulative environmental exposure assessment, the statewide heat vulnerability index (HVI) maps display the location and relative magnitude of exposure on three metrics: built environment (Place), future expected long-term temperature averages (Temperature), and population susceptibility (People). We observed varied and distinct patterns for each of the three component indices. We assessed how equitably those exposures are distributed by racial and socioeconomic factors. This analysis showed that each of the component indices and the aggregate HVI are disproportionately distributed along racial and socioeconomic lines in Michigan. Census tracts with higher percentages of people of color had larger exposure to HVI factors with a deviation from equity of -0.115 [95% CI -0.108, -0.122]. Similarly, for census tracts with higher percentage of people experiencing poverty, the deviation from equity was -0.101 [95% CI -0.094, -0.107]. The MI-Environment visualization tool can help communities prepare for climate change and resolve inequities by identifying census tracts with the most vulnerable residents and highest potential exposures.

Medial collateral ligament injuries and subsequent load on the anterior cruciate ligament: a biomechanical evaluation in a cadaveric model.

BACKGROUND: Numerous studies have documented the effect of complete medial collateral ligament injury on anterior cruciate ligament loads; few have addressed how partial medial collateral ligament disruption affects knee kinematics. PURPOSE: To determine knee kinematics and subsequent change in anterior cruciate ligament load in a partial and complete medial collateral ligament injury model. STUDY DESIGN: Controlled laboratory study. METHODS: Ten human cadaveric knees were sequentially tested by a robot with the medial collateral ligament intact, in a partial injury model, and in a complete injury model with a universal force-moment sensor measuring system. Tibial translation, rotation, and anterior cruciate ligament load were measured under 3 conditions: anterior load (125 N), valgus load (10 N x m), and internal-external rotation torque (4 N x m; all at 0 degrees and 30 degrees of flexion). RESULTS: Anterior and posterior translation did not statistically increase with a partial or complete medial collateral ligament injury at 0 degrees and 30 degrees of flexion. In response to a 125 N anterior load, at 0 degrees , the anterior cruciate ligament load increased 8.7% (from 99.5 to 108.2 N; P = .006) in the partial injury and 18.3% (117.7 N; P < .001) in the complete injury; at 30 degrees , anterior cruciate ligament load was increased 12.3% (from 101.7 to 114.2 N; P = .001) in the partial injury and 20.6% (122.7 N; P < .001) in the complete injury. In response to valgus torque (10 N x m) at 30 degrees , anterior cruciate ligament load was increased 55.3% (30.4 to 47.2 N; P = .044) in the partial injury model and 185% (86.8 N; P = .001) in the complete injury model. In response to internal rotation torque (4 N.m) at 30 degrees , anterior cruciate ligament load was increased 29.3% (27.6 to 35.7 N; P = .001) in the partial injury model and 65.2% (45.6 N; P < .001) in the complete injury model. The amount of internal rotation at 30 degrees of flexion was significantly increased in the complete injury model (22.8 degrees ) versus the intact state (19.5 degrees ; P < .001). CONCLUSION: Partial and complete medial collateral ligament tears significantly increased the load on the anterior cruciate ligament. In a partial tear, the resultant load on the anterior cruciate ligament was increased at 30 degrees of flexion and with valgus load and internal rotation torque. CLINICAL RELEVANCE: Patients may need to be protected from valgus and internal rotation forces after anterior cruciate ligament reconstruction in the setting of a concomitant partial medial collateral ligament tear. This information may help clinicians understand the importance of partial injuries of the medial collateral ligament with a combined anterior cruciate ligament injury complex.

Results of revision anterior cruciate ligament surgery.

BACKGROUND: Revision anterior cruciate ligament surgery remains challenging. PURPOSE: To analyze the authors' experience with revision anterior cruciate ligament surgery and determine the association between stability and functional results. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Between 1991 and 2002, 95 of 102 patients who underwent revision anterior cruciate ligament reconstruction at the authors' institution met the criteria for inclusion in the study. Of those, the 63 (66%) who returned for complete clinical and radiologic evaluation (mean follow-up, 72.7 months) formed the study group. Subjective evaluation focused on return to sports, arthritic symptoms, and subjective International Knee Documentation Committee criteria. Clinical evaluation included examination, KT-1000 arthrometer and functional testing, and radiographic analysis of alignment and arthritis. RESULTS: Based on International Knee Documentation Committee subjective scores and return to sports, results were rated as excellent/good in 45 patients (71%), fair in 6 (10%), and poor in 12 (19%). A grade IA or IIA Lachman and a KT-1000 arthrometer side-to-side difference of <3 mm (32/63 patients) was associated with a good/excellent result (P < .05). The mechanical axis was midline in 78% (49/63 patients). Radiographic arthritis (16 patients, 25%) was associated with duration of instability after primary failure (P < .03). Return to sports occurred in 59% (37/63 patients). Sixteen patients (25%) required a second revision surgery. CONCLUSION: Revision anterior cruciate ligament surgery allowed approximately 60% of patients to go back to sports, most of them at lower levels than their prerevision function. Instrumented laxity of <3 mm was associated with a better result. Radiographic arthritis was associated with duration of instability symptoms after primary failure. Patients who undergo revision anterior cruciate ligament surgery should be counseled as to the expected outcome and cautioned that this procedure probably represents a salvage situation and may not allow them to return to their desired levels of function.

Loose Body in Elbow of a Baseball Player: Arthroscopic/Radiologic Correlation.

We present the case of a 21 year old male college varsity baseball player who presented with sudden non-traumatic right elbow pain and limited range of motion. Plain radiographs suggested a calcified intra-articular body. Magnetic Resonance (MR) was performed to better characterize the location, consistency and mobility of this body. Multiple intra-articular bodies were found at subsequent arthroscopy. This case emphasizes the close correlation among the clinical, radiographic, MR and arthroscopic findings.