Preoperative Meniscal Extrusion Predicts Unsatisfactory Clinical Outcomes and Progression of Osteoarthritis after Isolated Partial Medial Meniscectomy: A 5-Year Follow-Up Study.

The objective of this study was to examine the association between preoperative meniscal extrusion of patients undergoing partial medial meniscectomy with clinical outcomes and progression of osteoarthritis and to determine the extent of meniscal extrusion associated with unsatisfactory clinical outcomes and progression of osteoarthritis. Ninety-five patients who underwent partial medial meniscectomy with a minimum follow-up of 5 years were retrospectively reviewed. Preoperative meniscal extrusion was evaluated with magnetic resonance imaging. Patients were assessed preoperatively and postoperatively with Lysholm and International Knee Documentation Committee (IKDC) subjective scores for clinical outcomes and with IKDC radiographic scale for osteoarthritis. An ANOVA (Analysis of Variance) was used to analyze the variations in meniscal extrusion and the clinical and radiological outcomes. A regression analysis was performed to identify factors that affect preoperative medial meniscus extrusion and that influence results after partial meniscectomy. An optimal cutoff value for meniscal extrusion associated with unsatisfactory clinical outcomes and progression of osteoarthritis was established. Significance was set at p < 0.05. The mean ± SD preoperative and postoperative Lysholm scores were 59.6 ± 15.5 versus 83.8 ± 13.1 (p < 0.001) and the mean preoperative and postoperative IKDC subjective scores were 59.4 ± 16.8 versus 82.0 ± 15.8 (p < 0.001). Meniscal extrusion greater than 2.2 mm (sensitivity, 84%; specificity, 81%) and 2.8 mm (sensitivity, 73%; specificity, 85%) was associated with unsatisfactory (poor/fair) Lysholm and IKDC subjective scores, respectively. The progression of osteoarthritis, characterized as a change of at least one category on the IKDC radiographic scale, occurred when meniscal extrusion was greater than 2.2 mm (sensitivity, 63%; specificity, 75%). Patients with higher body mass index (BMI) had significantly greater meniscal extrusion that patients with normal BMI (p < 0.001). The medial meniscus was more extruded in patients with horizontal and root tears. In conclusion, patients with preoperative meniscal extrusion of 2.2 mm or greater had unsatisfactory clinical outcomes and progression of osteoarthritis after partial medial meniscectomy at a minimum of 5 years follow-up. Higher BMI and horizontal and root tears were associated with greater preoperative meniscal extrusion.

Small lateral meniscus tears propagate over time in ACL intact and deficient knees.

PURPOSE: To quantify propagation of small longitudinal tears in the lateral meniscus in ACL intact and deficient knees. METHODS: Using a robotic testing system, 5-Nm of external tibial torque + 5-Nm of valgus torque + 250-N of axial compression was applied to 14 fresh-frozen cadaveric knees while the knees were flexed from 30° to 90°. Knees were divided into two groups: intact (N = 8) and ACL deficient (N = 6). Kinematic data was recorded for four knee states: intact or ACL deficient knee, after posterior arthrotomy, meniscus tear at baseline, and after 500 cycles of the applied loading condition. RESULTS: Lateral meniscus tear length increased throughout the 500 cycles regardless of the ACL integrity (p < 0.001). Overall, an increase of 28.7% and 26.1% was observed in intact and ACL deficient knees, respectively. In intact knees, external tibial rotation increased with meniscus tear propagation at all flexion angles by up to 45.5% (p = 0.019). In contrast, knee kinematics in ACL deficient knees were not affected by meniscus tear propagation (n.s.). In ACL deficient knees, resultant forces in the lateral meniscus increased at all flexion angles by up to 116.5% (p = 0.012). No differences in forces were observed in the intact knees (n.s.). CONCLUSION: The data of this study show that small longitudinal tears in the lateral meniscus propagate significantly regardless of the integrity of the ACL and even after only 100 cycles of knee loading. The propagation of such tears altered kinematics and forces in the knee. Therefore, small, longitudinal lateral meniscus tears that are untreated in current clinical practices may propagate when loaded.

Does Lateral Extra-articular Tenodesis of the Knee Affect Anterior Cruciate Ligament Graft In Situ Forces and Tibiofemoral Contact Pressures?

PURPOSE: To quantify the effects of lateral extra-articular tenodesis (LET) on tibiofemoral compartment contact area and pressures, knee kinematics, and forces. METHODS: Nine cadaveric knees were tested using a robotic testing system. Two loading conditions, (1) anterior tibial translational load coupled with axial compression and (2) internal tibial torque coupled with axial compression, were applied for each knee state at full extension and 30°, 60°, and 90° of knee flexion. Kinematic data was recorded for 3 knee states: anterolateral capsule (ALC) competent, ALC deficient, and post-LET using a 6-mm semitendinosus graft. In situ force in the anterior cruciate ligament (ACL) was quantified using the principle of superposition by comparing the change in force measured before and after the removal of the ALC. Contact area and pressures in each tibiofemoral compartment were measured by replaying kinematics after soft tissues were removed and pressure sensors were inserted. RESULTS: In response to an anterior tibial translational load, mean contact area in the medial compartment decreased by 33.1% from the ALC-competent to post-LET knee states at 90° of knee flexion (P = .042). No significant differences in lateral compartment contact pressure were found between knee states. In situ force in the ACL in response to an anterior tibial translational load decreased by 43.4% and 50% from the ALC-deficient to post-LET knee states at 60° (P = .02) and 90° (P = .006). No significant difference in kinematics was observed between the ALC-competent and post-LET knee states in each of the loading conditions at all knee flexion angles (P > .05). CONCLUSIONS: In this in vitro model, LET with a semitendinosus graft did not significantly overconstrain the knee or increase pressure in the lateral compartment. Additionally, LET reduced the in situ force in the ACL in the setting of ALC injury. CLINICAL RELEVANCE: The lack of knee overconstraint without significant increases in lateral compartment pressures indicates that if an LET with semitendinosus graft is not overtensioned, accelerated degenerative changes in the lateral compartment may not be expected after this procedure.

Partial Lateral Meniscectomy Affects Knee Stability Even in Anterior Cruciate Ligament-Intact Knees.

BACKGROUND: The effects of a partial lateral meniscectomy on knee kinematics and forces in the lateral meniscus are critical to understand. The purpose of this study was to quantify the effects of varying sizes of partial lateral meniscectomies of the posterior horn and a total lateral meniscectomy on knee kinematics and resultant forces in the lateral meniscus. METHODS: Using a robotic testing system, loads (134-N anterior tibial load + 200-N axial compression, 5-Nm internal tibial torque + 5-Nm valgus torque, and 5-Nm external tibial torque + 5-Nm valgus torque) were applied to 10 fresh-frozen cadaveric knees. The resulting joint motion and resultant forces in the lateral meniscus were determined for 4 knee states: intact, one-third and two-thirds partial lateral meniscectomies of the posterior horn, and total lateral meniscectomy. RESULTS: A decrease in lateral translation of the tibia (up to 166.7%) was observed after one-third partial lateral meniscectomies of the posterior horn compared with the intact knee, in response to an anterior load at all knee flexion angles tested (p < 0.05). One-third partial lateral meniscectomies of the posterior horn decreased the resultant forces in the lateral meniscus compared with the intact knee at all knee flexion angles tested in response to an anterior load (p < 0.05) and to an internal tibial torque (p < 0.05). The results of two-thirds partial lateral meniscectomies of the posterior horn were similar to those of one-third partial meniscectomies (p > 0.05). Total lateral meniscectomies further decreased the lateral translation of the tibia (up to 316.6%) compared with the intact knee in response to an anterior load (p < 0.05). CONCLUSIONS: The changes in joint motion and meniscal forces observed in this study after even small partial lateral meniscectomies may predispose knees to further injury. CLINICAL RELEVANCE: Surgeons should always consider repairing and minimizing the resection of even small lateral meniscal tears to prevent the potential deleterious effects of partial meniscectomy reported in this cadaveric study.

Effect of Meniscal Ramp Lesion Repair on Knee Kinematics, Bony Contact Forces, and In Situ Forces in the Anterior Cruciate Ligament.

BACKGROUND: Meniscal ramp lesions are possible concomitant injuries in cases of anterior cruciate ligament (ACL) deficiency. Although recent studies have investigated the influence of ramp lesions on knee kinematics, the effect on the ACL reconstruction graft remains unknown. PURPOSE/HYPOTHESIS: The purpose was to determine the effects of ramp lesion and ramp lesion repair on knee kinematics, the in situ forces in the ACL, and bony contact forces. It was hypothesized that ramp lesions will significantly increase in situ forces in the native ACL and bony contact forces and that ramp lesion repair will restore these conditions comparably with those forces of the intact knee. STUDY DESIGN: Controlled laboratory study. METHODS: Investigators tested 9 human cadaveric knee specimens using a 6 degrees of freedom robotic testing system. The knee was continuously flexed from full extension to 90° while the following loads were applied: (1) 90-N anterior load, (2) 5 N·m of external-rotation torque, (3) 134-N anterior load + 200-N compression load, (4) 4 N·m of external-rotation torque + 200-N compression load, and (5) 4 N·m of internal-rotation torque + 200-N compression load. Loading conditions were applied to the intact knee, a knee with an arthroscopically induced 25-mm ramp lesion, and a knee with an all-inside repaired ramp lesion. In situ forces in the ACL, bony contact forces in the medial compartment, and bony contact forces in the lateral compartment were quantified. RESULTS: In response to all loading conditions, no differences were found with respect to kinematics, in situ forces in the ACL, and bony contact forces between intact knees and knees with a ramp lesion. However, compared with intact knees, knees with a ramp lesion repair had significantly reduced anterior translation at flexion angles from full extension to 40° in response to a 90-N anterior load (P < .05). In addition, a significant decrease in the in situ forces in the ACL after ramp repair was detected only for higher flexion angles when 4 N·m of external-rotation torque combined with a 200-N compression load (P < .05) and 4 N·m of internal-rotation torque combined with a 200-N compression load were applied (P < .05). CONCLUSION: In this biomechanical study, ramp lesions did not significantly affect knee biomechanics at the time of surgery. CLINICAL RELEVANCE: From a biomechanical time-zero perspective, the indications for ramp lesion repair may be limited.

Long-Term Survival Analysis and Outcomes of Meniscal Allograft Transplantation With Minimum 10-Year Follow-Up: A Systematic Review.

PURPOSE: To investigate the long-term survivorship rates and functional outcomes of meniscal allograft transplantation (MAT) in patients with minimum 10-year postoperative follow-up. METHODS: Two reviewers independently searched EMBASE, MEDLINE, and PubMed from database inception for literature related to MAT according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Data are reported in a narrative summary fashion with descriptive statistics. RESULTS: Eleven studies with a total of 658 patients and 688 MATs were included. Mean age of patients was 33.1 years (range 14-66), of whom 63% were male. Mean survivorship rates were 73.5% at 10-year and 60.3% at 15-year follow-up, with 2 studies reporting 19- and 24-year survivorship of 50% and 15.1%, respectively. Pre- and postoperative Lysholm scores ranged from 36 to 60.5 and 61 to 75, respectively. Pre- and postoperative Tegner scores ranged from 1 to 3 and 2.5 to 4.6, respectively. Postoperative Knee injury and Osteoarthritis Outcome Score subset scores were as follows: Pain: 61.6 to 76.3; Symptoms: 57.9 to 61.8; Function in Daily Living: 68.5 to 79.9; Sport and Recreation: 33.9 to 49.3; Quality of Life: 37.3 to 45.9. Postoperative International Knee Documentation Committee scores ranged from 46 to 77. Regarding surgical technique, 194 MAT bone-fixation technique (53.8%) and 165 MAT suture-only fixation techniques (46.2%) were reported. The most common type of allograft used was cryopreserved (54.5% of the allografts). The most frequent concomitant procedures performed with MAT were to address chondral (20.8% of the cases) and ligament injuries (12.4% of the cases), and realignment procedures (9.4% of the cases). The most common complications observed that were not directly related to concomitant procedures were meniscal allograft partial tears (11.1%), arthrofibrosis (3.6%), and infection (2.0%). Several criteria were used among studies to define failure of MAT, the most common parameters being removal of meniscal allograft (8/11 studies) and conversion to total knee arthroplasty (7/11 studies). CONCLUSIONS: MAT can yield good long-term survivorship rates, with 73.5% and 60.3% of allografts remaining functional after 10 and 15 years, respectively. Functional outcomes 10 years after MAT were fair and improved compared with preoperative scores. LEVEL OF EVIDENCE: Level IV, systematic review of Level III and IV studies.

The effect of adipose-derived stem cells on enthesis healing after repair of acute and chronic massive rotator cuff tears in rats.

BACKGROUND: Chronic massive rotator cuff tears heal poorly and often retear. This study investigated the effect of adipose-derived stem cells (ADSCs) and transforming growth factor-ß3 (TGF-ß3) delivered in 1 of 2 hydrogels (fibrin or gelatin methacrylate [GelMA]) on enthesis healing after repair of acute or chronic massive rotator cuff tears in rats. METHODS: Adult male Lewis rats underwent bilateral transection of the supraspinatus and infraspinatus tendons with intramuscular injection of botulinum toxin A (n = 48 rats). After 8 weeks, animals received 1 of 8 interventions (n = 12 shoulders/group): (1) no repair, (2) repair only, or repair augmented with (3) fibrin, (4) GelMA, (5) fibrin + ADSCs, (6) GelMA + ADSCs, (7) fibrin + ADSCs + TGF-ß3, or (8) GelMA + ADSCs + TGF-ß3. An equal number of animals underwent acute tendon transection and immediate application of 1 of 8 interventions. Enthesis healing was evaluated 4 weeks after the repair by microcomputed tomography, histology, and mechanical testing. RESULTS: Increased bone loss and reduced structural properties were seen in chronic compared with acute tears. Bone mineral density of the proximal humerus was higher in repairs of chronic tears augmented with fibrin + ADSCs and GelMA + ADSCs than in unrepaired chronic tears. Similar improvement was not seen in acute tears. No intervention enhanced histologic appearance or structural properties in acute or chronic tears. CONCLUSIONS: Surgical repair augmented with ADSCs may provide more benefit in chronic tears compared with acute tears, although there was no added benefit to supplementing ADSCs with TGF-ß3.

Static Lateral Tibial Plateau Subluxation Predicts High-Grade Rotatory Knee Laxity in Anterior Cruciate Ligament-Deficient Knees.

BACKGROUND: In anterior cruciate ligament-deficient (ACL-D) knees, injury pattern and bony morphologic features have been shown to influence both static anterior tibial subluxation relative to the femur and dynamic rotatory knee laxity. Therefore, the relationship between static anterior tibial subluxation and dynamic rotatory knee laxity was investigated. PURPOSE: To determine whether static tibial subluxation as measured on magnetic resonance imaging (MRI) is associated with the grade of rotatory knee laxity in ACL-D knees. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Two-hundred fifty-eight knees underwent preoperative, image-guided assessment of lateral knee compartment translation during quantitative pivot shift (QPS). Subluxations of the medial and lateral tibial plateaus were measured on preoperative MRI in a subset of primary ACL-D knees meeting criteria for high-grade (QPS > 5.2 mm) and low-grade (QPS < 2.4 mm) rotatory laxity. Tibial subluxations on MRI were compared between patients with high- and low-grade rotatory laxity through use of pairwise t test and were analyzed via univariate and multivariate logistic regression. Significance was set at P < .05. RESULTS: On MRI, greater anterior subluxation of the lateral tibial plateau was observed in patients with high-grade compared with low-grade rotatory knee laxity (4.5 mm vs 2.3 mm; P < .05). No similar relationship was observed for the medial tibial plateau (-0.9 mm vs -0.4 mm; P > .05). Univariate logistic regression demonstrated that static subluxation of the lateral tibial plateau was associated with high-grade rotatory knee laxity (odds ratio [OR], 1.2; P < .05). An optimal cutoff of 2.95 mm of static lateral tibial subluxation was associated with high-grade rotatory knee laxity (sensitivity, 75%; specificity, 63%). Lateral meniscal injury was the first variable entered into a multivariate regression analysis and proved to be most associated with high-grade rotatory knee laxity (OR, 6.8; P < .05). When lateral meniscal injury was excluded from multivariate regression analysis, static anterior subluxation of the lateral tibial plateau alone was associated with high-grade rotatory knee laxity (OR, 1.2; P < .05). CONCLUSION: Data from this MRI study of two distinct rotatory knee laxity groups showed that static anterior subluxation of the lateral tibial plateau of 2.95 mm or greater was associated with high-grade rotatory knee laxity, and each millimeter increase of lateral tibial plateau subluxation was associated with a 1.2-fold odds of high-grade rotatory knee laxity. Anterior subluxation of the lateral tibial plateau on MRI was not independently associated with high-grade rotatory knee laxity in the presence of concomitant lateral meniscal injury. Static measurements made preoperatively may aid in predicting high-grade rotatory knee laxity and refining the indications for individualized knee surgery.