Biomechanical consequences of a complete radial tear adjacent to the medial meniscus posterior root attachment site: in situ pull-out repair restores derangement of joint mechanics.

BACKGROUND: Complete radial tears near the medial meniscus posterior root attachment site disrupt the circumferential integrity of the meniscus (similar to a posterior root avulsion). These tears can compromise the circumferential integrity, and they have been reported in biomechanical studies to be comparable with the meniscectomized state. PURPOSE: To quantify the tibiofemoral contact pressure and contact area changes that occur in cadaveric knees from complete posterior horn radial tears and subsequent repairs of the medial meniscus adjacent to the posterior root attachment site. STUDY DESIGN: Controlled laboratory study. METHODS: Six nonpaired fresh-frozen human cadaveric knees each underwent 45 different testing conditions: 9 medial meniscus conditions (intact, root avulsion, root repair, serial radial tear at 3, 6, and 9 mm from the root attachment site, and in situ repair at the same 3 distances from the root attachment site) at 5 flexion angles (0°, 30°, 45°, 60°, and 90°), under a 1000-N axial load. Tekscan sensors were used to measure contact area and pressure in the medial and lateral compartments. RESULTS: The medial meniscus root avulsion and all radial tear conditions resulted in significantly decreased contact area and increased mean contact pressure compared with the intact state for knee flexion angles beyond 0° (P < .05). The root repair and in situ repairs restored contact area and pressure to levels statistically indistinguishable from those of the intact meniscus and increased contact area and decreased contact pressure compared with the corresponding tear conditions. CONCLUSION: Posterior horn radial tears adjacent to the medial meniscus root that extend to the meniscocapsular junction can lead to derangement of the loading profiles of the medial compartment that are similar to a root avulsion. Repair of these radial tears with an in situ pull-out technique restored joint mechanics to the intact state. CLINICAL RELEVANCE: Complete radial tears of the posterior horn of the medial meniscus, which occur relatively frequently, are biomechanically equivalent to root avulsions and could potentially lead to medial compartment arthrosis. An in situ repair offers an alternative treatment to meniscectomy and can reestablish the posterior anchor point, thus improving load distribution in the medial compartment. Future clinical studies of these repairs are recommended.

Modified arthroscopic McLaughlin procedure for treatment of posterior instability of the shoulder with an associated reverse Hill-Sachs lesion.

Traumatic posterior shoulder dislocations are often accompanied by an impression fracture on the anterior surface of the humeral head known as a "reverse Hill-Sachs lesion". This bony defect can engage on the posterior glenoid rim and subsequently lead to recurrent instability and progressive joint destruction. We describe a new modified arthroscopic McLaughlin procedure, which allows for filling of the bony defect with the subscapularis tendon and subsequently prevents recurrence of posterior instability. This technique creates a double-mattress suture providing a large footprint for the subscapularis and a broader surface area to allow for effective tendon to bone healing. Furthermore, it obviates the need for detaching the subscapularis tendon and avoids the morbidity potentially associated with open procedures. Level of evidence V.

Qualitative and quantitative anatomic analysis of the posterior root attachments of the medial and lateral menisci.

BACKGROUND: The clinical importance of the meniscal posterior root attachments has been recently reported by both biomechanical and clinical studies. Although several studies have been performed to evaluate surgical techniques, there have been few studies on the quantitative arthroscopically pertinent anatomy of the posterior meniscal root attachments. HYPOTHESIS: The posterior root attachments of the medial and lateral menisci are consistent among specimens, and repeatable quantitative measurements using arthroscopically pertinent landmarks are achievable. STUDY DESIGN: Descriptive laboratory study. METHODS: Twelve nonpaired, fresh-frozen cadaveric knees were used. The positions of the posterior root attachments of the medial and lateral menisci were identified, and 3-dimensional measurements to arthroscopically pertinent landmarks were performed using a coordinate measuring system. RESULTS: The direct distance (±standard error of the mean) between the medial tibial eminence apex and the medial meniscus posterior root attachment center was 11.5 (±0.9) mm. When split into directional components along the knee's main axes, the medial meniscus posterior root attachment center was 9.6 (±0.8) mm posterior and 0.7 (±0.4) mm lateral along the bony surface from the medial tibial eminence apex. It was located 3.5 (±0.4) mm lateral from the medial articular cartilage inflection point and directly 8.2 (±0.7) mm from the nearest tibial attachment margin of the posterior cruciate ligament. The direct distance between the lateral tibial eminence apex and the lateral meniscus posterior root attachment center was 5.3 (±0.3) mm. When it was split into directional components using the knee's main axes, the lateral meniscus posterior root attachment center was 4.2 (±0.4) mm medial and 1.5 (±0.7) mm posterior from the lateral tibial eminence apex. The lateral meniscus posterior root attachment center was located 4.3 (±0.5) mm medial from the nearest articular cartilage margin and directly 12.7 (±1.1) mm from the nearest margin of the tibial attachment of the posterior cruciate ligament. CONCLUSION: This quantitative study reproducibly identified the posterior root attachment centers of the medial and lateral menisci in relation to arthroscopically pertinent landmarks and guidelines. CLINICAL RELEVANCE: These data can be directly applied to assist in anatomic meniscal root repairs.

Meniscal and chondral injuries associated with pediatric anterior cruciate ligament tears: relationship of treatment time and patient-specific factors.

BACKGROUND: Anterior cruciate ligament (ACL) tears are commonly associated with meniscal and chondral injuries. Although lateral meniscal tears are commonly associated with acute ACL injuries, the chronically ACL-deficient knee is associated with an increased rate of medial meniscal injury. These associations have been described in the adult knee literature. PURPOSE: To evaluate the relationship of elapsed time from injury with the incidence of meniscal and chondral injuries noted at the time of surgical treatment for ACL tears in pediatric patients. The effect of age, gender, weight, and mechanism of injury was also evaluated. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A retrospective chart review of pediatric patients undergoing primary arthroscopic ACL reconstruction between January 2005 and January 2011 was performed. The presence of meniscal tear, chondral injury, number of days from injury to treatment, age, weight, gender, and mechanism of injury were recorded. The data were analyzed for associations between elapsed time before surgery as well as patient-specific factors with rates of meniscal and chondral injuries. RESULTS: Three hundred seventy pediatric patients who underwent primary ACL reconstruction were included. Two hundred forty-one were treated ≤150 days (early) from injury, and 129 were treated >150 days (delayed) from injury. Ninety-one (37.8%) patients in the early treatment group and 69 (53.5%) patients in the delayed treatment group had medial meniscal tears (MMTs) (P = .014; odds ratio [OR], 1.8; 95% confidence interval [CI], 1.12-2.83). Lateral meniscal tear (LMT) rates were similar (56.0% and 57.4%) in each group. Age >15 years also influenced the presence of MMTs (P = .033; OR, 1.6; CI, 1.04-2.54). Increased patient weight was associated with an increased rate of MMTs and LMTs. Fifty-four of 170 (31.8%) patients weighing ≤65 kg and 106 of 200 (53%) weighing >65 kg had MMTs (P < .001; OR, 2.2; CI, 1.36-3.42). Eighty-two of 170 (48.2%) patients weighing ≤65 kg and 127 of 200 (63.5%) weighing >65 kg had LMTs (P < .018; OR, 1.7; CI, 1.10-2.68). The presence of chondral injury was significantly associated with the presence of meniscal tear in the same compartment of the knee. CONCLUSION: Pediatric patients treated >150 days after injury for ACL tears have a higher rate of MMT than those treated ≤150 days after injury. Increased age and weight are independently associated with a higher rate of MMT. Patients with ACL tears and an MMT or LMT are more likely to have a chondral injury in that particular compartment than those without meniscal tears.

What constitutes a Young and Burgess lateral compression-I (OTA 61-B2) pelvic ring disruption? A description of computed tomography-based fracture anatomy and associated injuries.

OBJECTIVE: The objectives of this study were to provide computed tomography (CT)-based description of the anatomic specifics of lateral compression (LC)-1 pelvic ring disruptions and to describe injury severity to other body systems and their correlation with fracture anatomy. DESIGN: Retrospective radiographic assessment and review of records SETTING: A level 1 trauma and tertiary referral center. PATIENTS/PARTICIPANTS: We identified a consecutive series of 100 patients with Young and Burgess LC-1 pelvic ring disruptions from the trauma registry database at a level 1 trauma center and evaluated their radiographs, CT scans, and injury and admission information. INTERVENTION: None. MAIN OUTCOME MEASUREMENTS: Presentation films were used to confirm injury type. The CT scan of the bony pelvis was reviewed for each patient by independent reviewers, with disagreement being resolved by the senior author. Sixteen categories were reviewed for each patient (rami fractures, segmental/comminuted rami fractures, Nakatani classification of rami fractures, anterior and posterior sacral fractures, and Denis classification). Sacral fractures were graded based on severity (0, no fracture; 1, buckle fracture; 2, simple fracture line; 3, comminuted fracture line). The age, Injury Severity Score (ISS), and 6 categories of Abbreviated Injury Scale (AIS) were recorded for each patient. A statistical analysis was performed to test the associations between fracture characteristics and injury severity. RESULTS: Our group had 54 women and 46 men. The mean age was 37.84 +/- 1.95. All patients but 3 had 1 or more rami fractures, and all but 2 had a sacral fracture. Of the 116 superior rami fractures, Nakatani 3 was the most common type (60/116, 51.7%). Of the 217 rami fractures, 47 (21.7%) were segmental or comminuted. Of the 98 anterior sacral injuries, there were 9 (9.2%) buckle fractures, 39 (39.8%) simple fractures, and 50 (51.0%) comminuted fractures. Of these 98 anterior sacral injuries, 47 (48.0%) were complete, passing through the sacrum and exiting the posterior cortex. Increasing severity of anterior sacrum fracture was associated with the presence of a complete sacral fracture (P < 0.0001). Of the 98 sacral fractures, 50 (50.0%) were Denis type 1, 41 (41.8%) Denis type II, and 7 (7.1%) Denis type III. Higher Denis types had higher likelihood of complete fractures of the sacrum (P < 0.0001). There was a significant association between the presence of a comminuted rami fracture and a complete sacrum injury (P = 0.003) and a trend to higher rates in Nakatani 2 superior rami fractures (P = 0.169). There were 4 deaths due to trauma in this group, and the mean ISS score was 17.16 +/- 1.3. The highest mean system AIS score in these patients was extremity (2.42 +/- 0.06) followed by chest (1.28 +/- 0.17) and abdomen (1.03 +/- 1.30). There was a trend to higher mean ISS scores (P = 0.2287) and significantly higher abdominal AIS scores (P = 0.0014) in those with a complete sacral fracture. Those with comminuted and complete sacral fractures were more likely to be symptomatic and require posterior ring stabilization (P = 0.003 and 0.043, respectively) CONCLUSIONS: LC-1 fractures of the pelvic ring represent a spectrum of injuries, with a large proportion having complete disruption of the sacrum. This complete injury of the sacrum is predicted by Denis type, severity of anterior ring disruption, abdominal AIS, and potentially location of rami fracture and ISS. CT scanning best defines these injuries.