A Biomechanical Study of Pivot-Shift and Lachman Translations in Anterior Cruciate Ligament-Sectioned Knees, Anterior Cruciate Ligament-Reconstructed Knees, and Knees With Partial Anterior Cruciate Ligament Graft Slackening: Instrumented Lachman Tests Statistically Correlate and Supplement Subjective Pivot-Shift Tests.

PURPOSE: To determine the statistical and predictive correlation between instrumented Lachman and pivot-shift tests with progressive loss of anterior cruciate ligament (ACL) function. METHODS: The kinematic correlations between pivot-shift and Lachman anterior tibial translations (ATTs) in ACL-deficient and ACL-reconstructed states and in partially lax ACL grafts were determined with precise robotic testing in cadaveric knees. The Lachman test (100-N anteroposterior) and 2 pivot-shift loadings were conducted: anterior tibial loading (100 N), valgus rotation (7 Nm), and internal rotation (5 Nm and 1 Nm). The tibia was digitized to study the resulting medial, central, and lateral tibiofemoral compartment translations. In group 1 knees, 15 bone-patellar tendon-bone reconstructions were first tested, followed by ACL graft loosening with 3- and 5-mm increases in Lachman ATT. In group 2, 43 knees underwent robotic testing before and after ACL sectioning and underwent analysis of the effect of 3- and 5-mm increases in Lachman ATT and complete ACL sectioning on pivot-shift compartment translations. RESULTS: In group 1 knees, ACL graft loosening allowing a 3-mm increase in Lachman ATT resulted in increases in pivot-shift lateral compartment translation (lateral compartment ATT) of only 1.6 ± 0.3 mm and 2.2 ± 1.0 mm (internal rotation of 5 Nm and 1 Nm, respectively) that were one-half of those required for a positive pivot-shift test finding. In group 2, for a 3-mm increased Lachman test, there were no positive pivot-shift values. In both groups, a Lachman test with an increase in ATT of 3 mm or less (100 N) had a 100% predictive value for a negative pivot-shift test finding. With ACL graft loosening and a 5-mm increase in the Lachman ATT, group 1 still had no positive pivot-shift values, and in group 2, a positive pivot-shift test finding occurred in 3 of 43 knees (7%, pivot shift 1-Nm internal rotation). After ACL sectioning, a highly predictive correlation was found between abnormal increases in Lachman and pivot-shift translations (P < .001). CONCLUSIONS: ACL graft slackening and an instrumented Lachman test with an increase in ATT of 3 mm or less were 100% predictive of a negative pivot-shift subluxation finding and retained ACL stability. Further graft slackening and a 5-mm increase in the Lachman ATT produced pivot-shift lateral compartment ATT increases still less than the values in the ACL-deficient state; however, 7% of the knees (3 of 43) were converted to a positive pivot-shift test finding indicative of ACL graft failure. CLINICAL RELEVANCE: Instrumented Lachman tests provide objective data on ACL function and graft failure to supplement subjective pivot-shift tests and are highly recommended for single-center and multicenter ACL studies. In the past decade, a near majority of published ACL studies no longer reported on instrumented Lachman tests, relying solely on highly subjective pivot-shift grading by multiple examiners.

Blood Flow Restriction Training Can Improve Peak Torque Strength in Chronic Atrophic Postoperative Quadriceps and Hamstrings Muscles.

PURPOSE: To report a prospective study of patients who underwent blood flow restriction training (BFRT) for marked quadriceps or hamstring muscle deficits after failure to respond to traditional rehabilitation after knee surgery. METHODS: The BFRT protocol consisted of 4 low resistance exercises (30% of 1 repetition maximum): leg press, knee extension, mini-squats, and hamstring curls with 60% to 80% limb arterial occlusion pressure. Knee peak isometric muscle torque (60° flexion) was measured on an isokinetic dynamometer. RESULTS: Twenty-seven patients (18 females, 9 males; mean age, 40.1 years) with severe quadriceps and/or hamstrings deficits were enrolled from April 2017 to January 2020. They had undergone a mean of 5.3 ± 3.5 months of outpatient therapy and 22 ± 10 supervised therapy visits and did not respond to traditional rehabilitation. Prior surgery included anterior cruciate ligament reconstruction, partial or total knee replacements, meniscus repairs, and others. All patients completed 9 BFRT sessions, and 14 patients completed 18 sessions. The mean quadriceps and hamstrings torque deficits before BFRT were 43% ± 16% and 38% ± 14%, respectively. After 9 BFRT sessions, statistically significant improvements were found in muscle peak torque deficits for the quadriceps (P = .003) and hamstring (P = .02), with continued improvements after 18 sessions (P = .004 and P = .002, respectively). After 18 BFRT sessions, the peak quadriceps and hamstring peak torques increased > 20% in 86% and 76% of the patients, respectively. The failure rate of achieving this improvement in peak quadriceps and hamstring torque after 18 BFRT sessions was 14% and 24%, respectively. CONCLUSIONS: BFRT produced statistically significant improvements in peak quadriceps and hamstring torque measurements after 9 and 18 sessions in a majority of patients with severe quadriceps and hamstring strength deficits that had failed to respond to many months of standard and monitored postoperative rehabilitation. LEVEL OF EVIDENCE: Level IV therapeutic case series.

Generalized Joint Laxity Is Associated With Increased Failure Rates of Primary Anterior Cruciate Ligament Reconstructions: A Systematic Review.

PURPOSE: To investigate patients with generalized joint laxity (GJL) after primary anterior cruciate ligament reconstruction (ACLR) as to the risk of ACLR failure, graft selection success rates, and overall clinical outcomes. METHODS: A systematic review of the PubMed and EMBASE databases was performed to identify studies published from the inception of the databases through February 4, 2020. The inclusion criteria were original studies written in English involving outcomes of patients with GJL who had undergone primary ACLR. RESULTS: Nine studies met the inclusion criteria, which included 1,869 patients. Most underwent isolated bone-patellar tendon-bone (BPTB; n = 1062) or hamstring autograft (n = 696) ACLR. Overall, higher graft failure rates tended to occur in patients with GJL compared with patients without GJL (range per study: 6%-30% vs 0%-12.3%). Inferior results were also found patients with GJL in patient-reported outcome measures and postoperative knee stability determined by KT, Lachman, and pivot-shift tests. BPTB autografts tended to have lower failure rates than hamstring autografts in patients with GJL (range per study: 6%-21% vs 17.6%-30%). Only 1 study determined outcomes of a combined ACLR and extra-articular augmentation in patients with GJL. CONCLUSIONS: Patients with GJL are at an increased risk of inferior outcomes and graft failure after primary ACLR. BPTB autografts may have more favorable stability outcomes compared with hamstring autografts in patients with GJL. However, the reported stability parameters and KT results, even with a BPTB autograft, remain inferior to non-GJL published results, and the added benefit of an extra-articular procedure to supplement the primary ACLR deserves consideration. LEVEL OF EVIDENCE: Level III, systematic review of Level II and III investigations.

Editorial Commentary: Measurements for Successful High Tibial Osteotomy: Understanding Supine Versus Standing and Intraoperative Fluoroscopic Alignment Is Required.

A high tibial osteotomy (HTO) that is used to correct varus malalignment, such as with medial arthrosis or before cartilage restoration or posterolateral reconstructions, represents an important and required surgery for clinical success. A major problem that occurs with HTO planning is that the preoperative measurements, with either lower limb supine or standing weight-bearing radiographs, will invariably show abnormal medial or lateral tibiofemoral compartment opening resulting from soft-tissue laxity or injury. It is imperative that this tibiofemoral joint opening be accounted for in the osteotomy correction calculations. There are well-described methods available that affect operative planning, such as the use of preoperative stress radiographs to determine the millimeters of tibiofemoral opening or closure. The use of intraoperative fluoroscopy with application of axial loading to the lower limb and verification of closure of the tibiofemoral joint is recommended. A careful fluoroscopic examination of the tibiofemoral compartments allows a final adjustment of the osteotomy correction and confirms the final weight-bearing line percent measurement and limb alignment. Postoperative radiographs are required to detect outliers resulting from unexpected soft-tissue laxity or inadequate correction.

Editorial Commentary: Long-Term Survivorship of Knee Meniscal Transplant Surgery-The Importance of Patient-Reported Outcomes With Magnetic Resonance Imaging Demonstration of Retained Meniscal Transplant Function.

The altered knee joint function and symptomatic state in younger patients after meniscectomy and progressive tibiofemoral arthritis remain an important unsolved treatment dilemma. Meniscal allograft transplantation has evolved as an acceptable treatment because there are few (if any) other options. The procedure is effective in most patients, who experience a decrease in tibiofemoral pain and improved knee function, even allowing a return to light recreational activities. However, biological remodeling of the implant occurs over time, with replacement of the complex circumferential and radial fibers with disorganized collagen tissues and altered cellular and proteoglycan components that affects load bearing and negates chondroprotective function. Positive patient outcomes may still be reported even with the loss of meniscal transplant function on magnetic resonance imaging giving a false-positive survivorship analysis. Repeated surgical procedures are frequent by 10 years. Patients are advised that meniscal allograft transplant surgery, although beneficial in the short term to buy time, is not curative.

Degenerative Meniscus Lesions: An Expert Consensus Statement Using the Modified Delphi Technique.

PURPOSE: The purpose of this study was to perform an evidence-based, expert consensus survey using the Delphi panel methodology to develop recommendations for the treatment of degenerative meniscus tears. METHODS: Twenty panel members were asked to respond to 10 open-ended questions in rounds 1 and 2. The results of the first 2 rounds served to develop a Likert-style questionnaire for round 3. In round 4, the panel members outside consensus were contacted and asked to either change their score in view of the group's response or argue their case. The level of agreement for round 4 was defined as 80%. RESULTS: There was 100% agreement on the following items: insidious onset, physiological part of aging, tears often multiplanar, not all tears cause symptoms, outcomes depend on degree of osteoarthritis, obesity is a predictor of poor outcome, and younger patients (<50 years) have better outcomes. There was between 90% and 100% agreement on the following items: tears are nontraumatic, radiographs should be weightbearing, initial treatment should be conservative, platelet-rich plasma is not a good option, repairable and peripheral tears should be repaired, microfracture is not a good option for chondral defects, the majority of patients obtain significant improvement and decrease in pain with surgery but results are variable, short-term symptoms have better outcomes, and malalignment and root tears have poor outcomes. CONCLUSIONS: This consensus statement agreed that degenerative meniscus tears are a normal part of aging. Not all tears cause symptoms and, when symptomatic, they should initially be treated nonoperatively. Repairable tears should be repaired. The outcome of arthroscopic partial meniscectomy depends on the degree of osteoarthritis, the character of the meniscus lesion, the degree of loss of joint space, the amount of malalignment, and obesity. The majority of patients had significant improvement, but younger patients and patients with short-term symptoms have better outcomes. LEVEL OF EVIDENCE: Level V - expert opinion.

Two Different Knee Rotational Instabilities Occur With Anterior Cruciate Ligament and Anterolateral Ligament Injuries: A Robotic Study on Anterior Cruciate Ligament and Extra-articular Reconstructions in Restoring Rotational Stability.

PURPOSE: To determine the effect of 2 extra-articular reconstructions on pivot-shift rotational stability and tibial internal rotation as a basis for clinical recommendations. METHODS: A robotic simulator tested 15 cadaver knees. Group 1 (anterior cruciate ligament [ACL] cut) underwent ACL bone-patellar tendon-bone reconstruction followed by sectioning the anterolateral structures and an extra-articular, manual-tension iliotibial band (ITB) tenodesis. Group 2 (ACL intact) tested the rotational stabilizing effect of a low-tension ITB tenodesis before and after sectioning the anterolateral ligament/ITB structures. Lateral and medial tibiofemoral compartment translations and internal-external tibial rotations were measured under Lachman, 5N·m tibial rotation, and 2 pivot-shift simulations using 4-degree-of-freedom loading. Statistical equivalence was defined within 2 mm tibiofemoral compartment translation and 2° tibial rotation at P < .05. RESULTS: The bone-patellar tendon-bone ACL reconstruction (group 1) restored pivot-shift lateral compartment translation within 0.7 mm (95% confidence interval [CI], -0.6 to 1.9; P = .70) of normal. The internal rotation limit was not affected by ACL sectioning or reconstruction. After anterolateral ligament/ITB sectioning there was no change in pivot-shift lateral compartment translation, however internal rotation increased 2.9° (95% CI, 0.6-5.2; P = .99) at 90° flexion. The manual-tension ITB tenodesis (fixated 13-22 N tension) decreased pivot-shift lateral compartment translation 4.8 mm (95% CI, 1.4-8.1; P = .99) and internal rotation by 21.9° (95% CI, 13.2-30.6; P = .99) at 90° flexion. The ACL forces decreased 45.8% in the pivot-shift test. In group 2 knees, with the ACL intact, the anterolateral ligament/ITB sectioning had no effect on pivot-shift translations; however, the internal rotation limit increased by 4.3° (95% CI, 1.9-6.8; P = .99) at 60° flexion. The low-tension ITB tenodesis (fixated 8.9 N tension) had no effect on pivot-shift translations and corrected internal tibial rotation with a mild overconstraint of 4.2° (95% CI, 1.9-6.8; P = .99) at 60° flexion. CONCLUSIONS: A low-tension ITB tenodesis, fixated at neutral tibial rotation to avoid constraining internal tibial rotation, has no effect in limiting abnormal pivot-shift subluxations. CLINICAL RELEVANCE: A low-tension ITB tenodesis has limited clinical utilization as the pivot-shift subluxations are not affected, assuming appropriate tensioning to not overconstrain internal tibial rotation.

Low-impact sports activities are feasible after meniscus transplantation: a systematic review.

PURPOSE: To determine sports activities achieved after meniscus transplantation and if associations exist between sports activity levels and transplant failure or progression of tibiofemoral osteoarthritis (OA). METHODS: A systematic search was performed using PubMed and Cochrane online databases. Inclusionary criteria were English language, clinical trials published from 1996 through May 2017, minimum 2 years of follow-up, and sports activity data reported. RESULTS: Twenty-eight studies were included in which 1521 menisci were implanted into 1497 patients. The mean age was 34.3 ± 6.7 years, and the mean follow-up was 5.0 ± 3.7 years. Details on sports activities were provided in 7 studies (285 patients) that reported 70-92% of patients returned to a wide variety of sports activities. Mean Tegner activity scores were reported in 24 investigations. The mean score was <5 in 58% of these studies, indicating many patients were participating in light recreational activities. There was no association between mean Tegner scores and transplant failure rates. A moderate correlation was found between failure rates and mean follow-up time (R = 0.63). The effect of sports activity levels on progression of tibiofemoral OA could not be determined because of limited data. Only two studies determined whether symptoms occurred during sports activities; these reported 1/38 (3%) and 5/69 (7%) patients had knee-related problems. CONCLUSIONS: It appeared that the majority of individuals returned to low-impact athletic activities after meniscus transplantation. The short-term follow-up did not allow for an analysis on the effect of return to high-impact activities on transplant failure rates or progression of OA. LEVEL OF EVIDENCE: IV.

Anterolateral Ligament and Iliotibial Band Control of Rotational Stability in the Anterior Cruciate Ligament-Intact Knee: Defined by Tibiofemoral Compartment Translations and Rotations.

PURPOSE: To determine the stabilizing effect of the anterolateral ligament (ALL) and iliotibial band (ITB) in resisting internal tibial rotation limits and anterior subluxations of the tibiofemoral compartments in anterior cruciate ligament (ACL)-intact knees during anterior drawer, internal rotation, and under 2 different 4-degree-of-freedom pivot-shift conditions. METHODS: A 6-degree-of-freedom robotic simulator tested 19 fresh-frozen cadaver specimens with 3 testing conditions: intact, ALL- or ITB-sectioned (random), and both ALL and ITB sectioned. Anterior translation of the medial and lateral compartments and internal tibial rotation were measured under 100 N anterior drawer, 5 Nm internal rotation, and 2 pivot-shift conditions. Statistical equivalence was defined as P < .05. RESULTS: Sectioning the ALL alone had no effect on lateral compartment translation or internal rotation under any loading condition (equivalent P < .05). After ITB sectioning alone, small increases in internal rotation were found under 5 Nm internal rotation at 60° (3.0° [90% confidence interval 1.9-4.1]; P = .99) and 90° (2.2° [90% confidence interval 1.5-2.9]; P = .84) flexion. After both ALL and ITB were sectioned, increases in internal rotation of 1.7°, 4.5°, and 3.9° occurred at 25°, 60°, and 90° flexion, respectively (P > .05). Small increases in pivot-shift internal rotation (Group 1: 2.0° [90% confidence interval 1.4-2.6]; P = .52) and lateral compartment translation occurred (Group 1: 0.9 mm [90% confidence interval 0.7-1.1]; P < .001). CONCLUSIONS: Sectioning the ALL does not lead to an increase in tibiofemoral compartment subluxations in the pivot-shift test with an intact ACL. Accordingly the ALL would not represent a primary restraint to pivot-shift subluxations. ALL sectioning alone does not lead to an increase in internal rotation motion limits, however sectioning both the ALL and ITB did produce small increases in rotation limits at higher flexion angles which would likely not be clinically detectable. CLINICAL RELEVANCE: A deficiency to both the ALL and ITB during in vitro-simulated pivot-shift tests and internal rotation tests results in small, clinically undetectable changes in knee kinematics in the majority of knees assuming intact ACL function.

Editorial Commentary: Lateral Extra-articular Reconstructions With Anterior Cruciate Ligament Surgery: Are These Operative Procedures Supported by In Vitro Biomechanical Studies?

There remains controversy on the role of a concurrent lateral extra-articular procedure with anterior cruciate ligament (ACL) reconstruction. Previous biomechanical studies often are historical and inconclusive. Studies show the anterolateral ligament and iliotibial band are secondary restraints and, when injured in conjunction with the ACL, produce gross (Grade 3) pivot-shift subluxations. Recent robotic studies show a well-placed bone-patellar tendon-bone reconstruction does restore time-zero kinematics with a negative pivot-shift. Accordingly, a lateral extra-articular procedure does not provide any further resistance to the pivot-shift. Extra-articular reconstructions may produce a modest unloading of an ACL graft and reduce a few degrees of abnormal internal rotation at high flexion angles but at the expense of overconstraining the knee joint. The conclusion appears warranted at this time that biomechanical studies do not support the routine addition of anterolateral ligament or iliotibial band tenodesis procedures with ACL reconstructions. These procedures may, however, still play a role in select ACL chronic or revision knees with gross anterior subluxations.

Effect of anteromedial and posterolateral anterior cruciate ligament bundles on resisting medial and lateral tibiofemoral compartment subluxations.

PURPOSE: This study analyzed the interaction of the anteromedial and posterolateral portions of the anterior cruciate ligament (ACL) in resisting medial and lateral tibiofemoral compartment subluxations under multiple loading conditions. METHODS: By use of a 6-df robotic simulator, 10 human cadaveric knees were tested in 3 states: intact ACL, partial ACL (loss of either the anteromedial bundle [AMB] or posterolateral bundle [PLB]), and deficient ACL. The testing profile involved anterior-posterior translation and internal-external rotation, as well as 3 pivot-shift loading conditions with varying internal rotation torque (1- or 5-Nm) and coupled anterior force (35- or 100-N). Digitization of anatomic landmarks provided tibiofemoral compartment translations and centers of tibial rotation. RESULTS: During pivot-shift testing (100-N anterior force, 1-Nm internal rotation torque, and 7-Nm valgus), the lateral and medial compartment anterior translation increased by a mean of 2.5 ± 0.8 mm (P = .016) and 3.4 ± 2.0 mm (P = .001), respectively, on AMB sectioning and 1.3 ± 0.9 mm (P = .329) and 0.6 ± 0.7 mm (P = .544), respectively, on PLB sectioning. Higher internal rotation torque (5 Nm v 1 Nm) on pivot-shift testing reduced central and medial anterior translation after ACL sectioning. There was no change in internal rotation on AMB or PLB sectioning. During the Lachman test (100-N), AMB and PLB sectioning increased central translation by 3.6 ± 1.6 mm (P = .001) and 0.7 ± 0.6 mm (P = .498), respectively. CONCLUSIONS: Both ACL bundles function synergistically in resisting medial and lateral compartment subluxations on the Lachman and pivot-shift tests. The AMB provided more restraint to anterior tibial translation during both tests as compared with the PLB. PLB sectioning produced no statistically significant change in anterior translation on the Lachman or pivot-shift test. Neither bundle contributed to resisting internal rotation. CLINICAL RELEVANCE: An ACL graft designed to duplicate the AMB would theoretically resist medial and lateral compartment anterior subluxations under multiple loading conditions. The PLB provides a secondary restraint at low flexion angles. Neither ACL bundle resists internal tibial rotation or allows a positive pivot-shift subluxation.

Anatomic Single-Graft Anterior Cruciate Ligament Reconstruction Restores Rotational Stability: A Robotic Study in Cadaveric Knees.

PURPOSE: First, we aimed to investigate the ability of a single bone-patellar tendon-bone graft placed in the anatomic center of the femoral and tibial attachment sites to restore normal tibiofemoral compartment translations and tibial rotation. Second, we aimed to investigate what combination of anterior load and internal rotation torque applied during a pivot-shift test produces maximal anterior tibiofemoral subluxations. METHODS: We used a 6-df robotic simulator to test 10 fresh-frozen cadaveric specimens under anterior cruciate ligament (ACL)-intact, ACL-sectioned, and ACL-reconstructed conditions measuring anterior translations of the medial, central, and lateral tibiofemoral compartments and degrees of tibial rotation. Specimens were loaded under Lachman, anterior limit, and internal rotation conditions, as well as 3 different pivot-shift conditions. RESULTS: On ACL sectioning, compartment translations in the Lachman and 3 pivot-shift tests increased significantly and were restored to ACL-intact values after single-graft ACL reconstruction. In the pivot-shift tests, the single graft restored lateral and medial compartment translations (e.g., group 3, within 1.3 ± 0.6 mm and 0.8 ± 0.6 mm, respectively, of the ACL-intact state and internal rotation within 0.7° ± 1.2°). Anterior subluxation of the medial compartment during pivot-shift loading was reduced when internal rotation torque was increased from 1 to 5 Nm (P < .0001). CONCLUSIONS: A single-graft ACL reconstruction performed at the central femoral and tibial ACL attachment sites restored anterior-posterior translation and tibial rotation motion limits. In addition, rotational knee stability as defined by tibiofemoral compartment translations was restored under all simulated pivot-shift testing conditions. CLINICAL RELEVANCE: This study provides in vitro evidence to support the clinical use of single-graft ACL reconstructions in restoring tibiofemoral compartment translations. It also shows the advantage of describing ACL insufficiency in terms of medial and lateral compartment subluxations as compared with the common approach of describing changes in central tibial translations and rotations.

A systematic review of the incidence and clinical significance of postoperative meniscus transplant extrusion.

PURPOSE: To determine the incidence and clinical significance of postoperative meniscus transplant extrusion. METHODS: A systematic search was performed using PubMed and Cochrane online databases. Inclusionary criteria were English language, clinical trials of meniscus transplantation published from 1984 to 2014, and meniscus extrusion measured on magnetic resonance imaging (MRI). RESULTS: Twenty-three studies were included, in which 814 menisci were implanted into 803 patients. MRIs were obtained from 2 days to 10 years postoperatively. Eighteen studies used fresh-frozen meniscus transplants implanted with bone (n = 612) or suture fixation (n = 116); four studies, cryopreserved transplants; and one, irradiated transplants. Three measurements assessed extrusion: absolute millimeters of extrusion (0-8.8 mm), relative percentage of extrusion (0-100%), and the percent of transplants that were extruded (0-100 %). Relationships between transplant extrusion and clinical rating scales, joint space narrowing on standing radiographs, and arthrosis progression were inconclusive. Non-anatomic placement of lateral meniscus transplants and suture fixation of medial and lateral transplants were associated with greater extrusion in two studies. CONCLUSIONS: Inconsistencies among studies prevent conclusions regarding the incidence and clinical significance of meniscus transplant extrusion. Even so, the short- to mid-term results were encouraging for knee function with daily activities and low rates of failure requiring transplant removal. A postoperative MRI showing more than 3-mm extrusion occurring in some studies suggested technique and/or implant sizing problems that required correction. Future studies should report absolute transplant extrusion, relative percent of extrusion, percent of transplant within the tibiofemoral compartment, and the percent of transplants that are extruded. LEVEL OF EVIDENCE: IV.

Neuromuscular retraining intervention programs: do they reduce noncontact anterior cruciate ligament injury rates in adolescent female athletes?

PURPOSE: The purpose of this study was to identify neuromuscular training intervention programs that significantly reduced the incidence of noncontact anterior cruciate ligament (ACL) injury rates in female adolescent athletes. METHODS: A systematic search of PubMed was conducted to determine the outcome of ACL neuromuscular retraining programs in a specific population. The inclusion criteria were English language, published from 1994-2013, original clinical trials, all evidence levels, female athletes aged 19 years or younger, and noncontact ACL injury incidence rates determined by athlete-exposures. RESULTS: Of 694 articles identified, 8 met the inclusion criteria. Three training programs significantly reduced noncontact ACL injury incidence rates in female adolescent athletes. These were the Sportsmetrics, Prevent Injury and Enhance Performance, and Knee Injury Prevention programs. The estimated number of athletes who needed to train to prevent 1 ACL injury in these 3 studies ranged from 70 to 98, and the relative risk reduction ranged from 75% to 100%. Five programs did not significantly reduce noncontact ACL injury incidence rates. The ACL injury incidence rates for control subjects were lower in these studies (0.03 to 0.08 per 1,000 athlete-exposures) than in those investigations that had a significant effect (0.21 to 0.49 per 1,000 athlete-exposures). There was wide variability among all programs in the frequency, duration, and timing of training; how training was conducted, supervised, or controlled; the components of the program; how exposure data were calculated; noncontact ACL injury incidence rates in the control groups; and compliance with training. CONCLUSIONS: Three ACL intervention programs successfully reduced noncontact ACL injury incidence rates in female adolescent athletes. Pooling of data of all ACL intervention programs is not recommended because of numerous methodologic differences among studies. LEVEL OF EVIDENCE: Level II, systematic review of Level I and II studies.

Clinical healing rates of meniscus repairs of tears in the central-third (red-white) zone.

PURPOSE: To determine the clinical healing rate of repairs of meniscus tears that extend into the central one-third region and the factors that affect the outcome. METHODS: A systematic search of PubMed was conducted to determine the outcome of meniscus repairs in the red-white (R/W) zone. Inclusion criteria were as follows: English language, clinical trials published from 1996 to 2013, R/W tears analyzed separately from tears in other zones, arthroscopic suture-based repairs, and all evidence levels. RESULTS: Of 344 articles identified, 23 met the inclusion criteria. There were 1,232 patients who had 1,326 meniscus repairs, of which 767 were in the R/W zone. Concurrent anterior cruciate ligament reconstruction was performed in 955 patients (78%). The mean age was 25 years, and the mean follow-up was 4 years. Evaluation criteria included clinical examination in 22 studies, follow-up arthroscopy in 15, magnetic resonance imaging in 6, weight-bearing radiographs in 3, and the International Knee Documentation Committee subjective score in 1. Overall, 637 (83%) of the repairs were considered clinically healed because no additional surgery was required and no obvious clinical meniscus symptoms were detected. This included 382 of 470 inside-out suture repairs (81%) and 255 of 297 all-inside suture repairs (86%). Twenty-two factors were assessed in 13 studies to determine their influence on the outcome, with varying results. Authors generally found that patient age, chronicity of injury, involved tibiofemoral compartment, gender, and concurrent anterior cruciate ligament reconstruction did not adversely affect the results. Insufficient data existed to assess the healing rates according to the type of meniscus tear except for single longitudinal tears. Complications were reported in 3% of the patients in this review. Long-term assessment of a chondroprotective effect of the repairs was conducted in only 2 studies. CONCLUSIONS: An acceptable midterm clinical healing rate was found for R/W meniscus repairs, supporting this procedure when appropriately indicated. Long-term studies assessing the chondroprotective effect in the involved tibiofemoral compartment using magnetic resonance imaging and radiographs are needed. LEVEL OF EVIDENCE: Level IV, systematic review of Level I-IV studies.

Return to Sports in Patients Aged 50 Years or Younger After Robotic-Assisted Patellofemoral Arthroplasty: A 10-Year Experience Reporting High Clinical Benefits and High Patient Satisfaction With Return to an Active Lifestyle.

BACKGROUND: Limited data are available on return to sports and patient psychometric ratings of success after patellofemoral arthroplasty (PFA) in younger patients with high expectations to return to an active lifestyle. PURPOSE/HYPOTHESIS: The purpose of this article was to determine the role of PFA and its success in meeting patient expectations regarding the return to low-impact recreational sports and an active lifestyle in younger, active patients. It was hypothesized that PFA would allow younger patients to return to low-impact sports and an active lifestyle and achieve high patient psychometric ratings. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: In this 10-year prospective study (2009-2018), robotic-assisted PFA was performed on 44 patients (32 women and 12 men; n = 51 consecutive knees), with a mean age of 37.2 years (range, 21-50 years). The follow-up rate was 98%, with a mean of 5.3 years (range, 2-9.3 years). Primary clinical outcomes were as follows: the validated Cincinnati Knee Rating System sports activity and symptom rating scales, patient psychometric ratings of the substantial clinical benefit (SCB), and the Patient Acceptable Symptom State (PASS). Secondary outcomes were the Cincinnati Knee Rating System occupational rating, visual analog pain scale, and the 12-Item Short Form Health Survey. Survivorship was defined by conversion to total knee replacement (TKR). RESULTS: Before PFA, 78% of patients (35/45 knees) were symptomatic and unable to perform recreational sports, with only 20% of patients (9/45 knees) performing some low-impact sports. After PFA, 80% of patients (36/45 knees) were able to perform low-impact sports, and 7% (3/45 knees) performed jumping-pivoting sports (P < .001). The SCB scored by the patient showed 87% of knees as good, very good, or normal. On the PASS analysis, 89% of patients (95% CI, 76%-96%) were "pleased," and 93% (95% CI, 82%-99%) would undergo surgery again. There were clinically relevant improvements in symptoms of pain, swelling, and giving way (P = .0001). Preoperatively, 91% of knees had moderate to severe pain with activities of daily living, and only 11% of knees had pain at the follow-up. Five of the 50 knees (10%) underwent TKR conversion with one patient lost to follow-up. CONCLUSION: PFA resulted in a high return of patients to low-impact sports with high SCB and PASS psychometric ratings. The robotic-assisted 3-dimensional preoperative planning allowed precise intraoperative trochlear implant alignment in knees with severe trochlear dysplasia. PFA is recommended as an alternative treatment in younger patients with end-stage symptomatic patellofemoral arthritis. REGISTRATION: NCT02738476 (ClinicalTrials.gov identifier).

Advanced patellofemoral cartilage lesions in patients younger than 50 years of age: is there an ideal operative option?

PURPOSE: The purpose of this review was to determine if there is an ideal operation for large symptomatic articular cartilage lesions on the undersurface of the patella in young patients. METHODS: A systematic search of PubMed was conducted to determine the outcome of operations performed for large patellar lesions in young patients. Inclusionary criteria were English language, original clinical trials published from 1992 to 2012, patellar lesions 4 cm(2) or larger, mean patient age 50 years or younger, and all evidence levels. RESULTS: Of 991 articles identified, 18 met the inclusionary criteria, encompassing 840 knees in 828 patients. These included 613 knees that underwent autologous chondrocyte implantation (ACI) (11 studies), 193 knees that had patellofemoral arthroplasty (PFA) (5 studies), and 34 knees that underwent osteochondral allografting (OA) (2 studies). The mean patient age was 37.2 years and the mean follow-up was 6.2 years. Long-term follow-up (>10 years) was available in only 4 studies (2 PFA, 1 ACI, 1 OA). All studies except one were Level IV and none were randomized or had a control group. Twenty-one outcome instruments were used to determine knee function. When taking into account knees that either failed or had fair/poor function, the percentage of patients who failed to achieve a benefit averaged 22% after PFA and 53% after OA and ranged from 8% to 60% after ACI. In addition, all 3 procedures had unacceptable complication and reoperation rates. CONCLUSIONS: The combination of failure rates and fair/poor results indicated that all 3 procedures had unpredictable results. We concluded that a long-term beneficial effect might not occur in one of 3 ACI and PFA procedures and in 2 of 3 OA procedures. We were unable to determine an ideal surgical procedure to treat large symptomatic patellar lesions in patients 50 years or younger. LEVEL OF EVIDENCE: Level IV, systematic review of Level I to IV studies.

A training program to improve neuromuscular and performance indices in female high school soccer players.

The purpose of this study was to determine if a sports-specific anterior cruciate ligament injury prevention training program could improve neuromuscular and performance indices in female high school soccer players. We combined components from a published knee ligament intervention program for jump and strength training with other exercises and drills to improve speed, agility, overall strength, and aerobic fitness. We hypothesized that this program would significantly improve neuromuscular and athletic performance indices in high school female soccer players. The supervised 6-week program was done 3 d·wk(-1) for 90-120 minutes per session on the soccer fields and weight room facilities in area high schools. In phase 1, 62 athletes underwent a video drop-jump test, t-test, 2 vertical jump tests, and a 37-m sprint test before and upon completion of the training program. In phase 2, 62 other athletes underwent a multistage fitness test before and after training. There were significant improvements in the mean absolute knee separation distance (p < 0.0001), mean absolute ankle separation distance (p < 0.0001), and mean normalized knee separation distance (p < 0.0001) on the drop-jump, indicating a more neutral lower limb alignment on landing. Significant improvements were found in the t-test (p < 0.0001), estimated maximal aerobic power (p < 0.0001), 37-m sprint test (p = 0.02), and in the 2-step approach vertical jump test (p = 0.04). This is the first study we are aware of that demonstrated the effectiveness of a knee ligament injury prevention training program in improving athletic performance indices in high school female soccer players. Future studies will determine if these findings improve athlete compliance and team participation in knee ligament injury intervention training.

Functional Interaction of the Cruciate Ligaments, Posteromedial and Posterolateral Capsule, Oblique Popliteal Ligament, and Other Structures in Preventing Abnormal Knee Hyperextension.

BACKGROUND: The ligaments and soft tissue capsular structures of the knee joint that provide a resisting force to prevent abnormal knee hyperextension have not been determined. This knowledge is required for the diagnosis and treatment of knee hyperextension abnormalities. PURPOSE: To determine the resisting moment of knee ligament and capsular structures that resist knee hyperextension. HYPOTHESIS: The combined posteromedial and posterolateral capsular structures function to provide a major restraint to prevent abnormal knee hyperextension. The anterior and posterior cruciate ligaments resist knee hyperextension but function as secondary restraints. STUDY DESIGN: Descriptive laboratory study. METHODS: A 6 degrees of freedom robotic system determined intact laxity limits in 24 cadaveric knees from 0° to 100° of knee flexion for anteroposterior limits at ±135 N, abduction-adduction limits at ±7 N·m, and external-internal limits at ±5 N·m. One loading method (n = 14 knees) used a static loading sequence with knee hyperextension to 27-N·m torque while maintaining all other degrees of freedom at zero load during sequential soft tissue cutting. The second method (n = 10 knees) used a cyclic loading sequence to decrease viscoelastic effects with soft tissue cutting at 0° of extension, followed by knee hyperextension to 27-N·m torque and cycled back to 0°. Selective soft tissue cuttings were performed of the following: oblique popliteal ligament, fabellofibular ligament, posterolateral capsule, posteromedial capsule with posterior oblique ligament, cruciate ligaments, lateral collateral ligament, popliteus, anterolateral ligament and iliotibial band, and superficial plus deep medial collateral ligaments. The sequential loss in the restraining moment with sectioning provides the function of that structure in resisting knee hyperextension. RESULTS: The median resisting force to knee hyperextension, in descending order, was the posteromedial capsule and posterior oblique ligament (21.7%), posterorolateral ligament and fabellofibular ligament (17.1%), anterior and posterior cruciate ligaments (13% and 12.9%, respectively), superior and deep medial collateral ligament (9.6%), oblique popliteal ligament (7.7%), and lateral collateral ligament (5.4%). The combined posterior capsular structures provided 54.7% and the anterior and posterior cruciate ligaments 25.3% of the total resisting moment to prevent knee hyperextension. CONCLUSION: Diagnosis of abnormal knee hyperextension involves a combination of multiple ligament and soft tissue structures without 1 primary restraint. The posteromedial and posterolateral capsular structures provided the major resisting moment to prevent knee hyperextension. The cruciate ligaments produced a lesser resisting moment to knee hyperextension. CLINICAL RELEVANCE: This is the first study to comprehensively measure all of the knee ligaments and capsular structures providing a resisting moment to abnormal knee hyperextension. These data are required for diagnostic and treatment strategies on the pathomechanics of abnormal knee hyperextension in patients after injury or developmental cases.

Treatment of meniscus tears during anterior cruciate ligament reconstruction.

PURPOSE: To define the incidence of meniscectomy, meniscus repair, and meniscus tears left in situ during anterior cruciate ligament (ACL) reconstruction. METHODS: A systematic search of PubMed and 7 sports medicine journal databases was performed to determine the treatment of meniscus tears during ACL reconstruction. Inclusion criteria were English language, publication in the last 10 years, clinical trials, all evidence levels, and skeletally mature or immature knees. Exclusion criteria were revision ACL reconstruction, concomitant ligament reconstruction, and studies with exclusion or inclusion criteria regarding meniscus surgery during ACL reconstruction. RESULTS: Of 634 articles identified, 159 met the inclusion criteria, encompassing 19,531 patients. There were 11,711 meniscus tears; they were treated by meniscectomy in 65% (7,621 tears), treated by repair in 26% (3,022 tears), or left in situ in 9% (1,068 tears). Only 19 studies analyzed the treatment of meniscus tears according to the tibiofemoral compartment. These reported medial compartment tears were treated by meniscectomy in 63%, treated by repair in 27%, and left in situ in 9%. Lateral compartment tears were treated by meniscectomy in 71%, treated by repair in 14%, and left in situ in 14%. Only 24 studies identified the type of meniscus repair procedure performed. In 33 studies (21%) repair was performed more frequently than meniscectomy. CONCLUSIONS: Meniscectomy is performed 2 to 3 times more frequently than meniscus repair during ACL reconstruction. We were unable to analyze the effect of the location and type of meniscus tear, sex, age, or chronicity of injury on the treatment of meniscus tears. The number of potentially repairable meniscus tears that were treated by resection could not be identified. CLINICAL RELEVANCE: This study found that meniscectomy was performed in 65% of meniscus tears. This is concerning because studies have shown that, regardless of knee stability obtained after ACL reconstruction, meniscectomy accelerates degenerative joint changes. LEVEL OF EVIDENCE: Level IV, systematic review of Level I to IV studies.