Greater Knee Laxity Research Articles

Quadriceps tendon autograft ACL reconstruction has less pivot shift laxity and lower failure rates than hamstring tendon autografts.

Quadriceps tendon (QT) autograft ACL reconstruction was hypothesized to possess less anterior knee laxity, pivot shift laxity, and lower failure rates than hamstring tendon (HT) autografts. Terms "hamstring tendon autograft" and "ACL reconstruction" or "quadriceps tendon autograft" and "ACL reconstruction" were searched in Embase and PubMed. Inclusion criteria required that studies included patients treated for primary ACL injury with reconstruction using either a QT autograft (Group 1) or a HT autograft (Group 2) and instrumented anterior knee laxity assessment. Extracted information included surgical fixation method, graft type, graft thickness or diameter, single vs. double bundle surgical method, publication year, time between the index knee injury and surgery, % women, initial and final subject number, subject age, follow-up length, side-to-side anterior knee laxity difference, Lysholm Score, Subjective IKDC score, anterior knee laxity side-to-side difference grade, ipsilateral pivot shift laxity grade, and failure rate. The Methodological Index for Nonrandomized Studies was used to evaluate study methodological quality. The QT group (Group 1) had 17 studies and the HT group (Group 2) had 61 studies. Overall, Group 2 had greater pivot shift laxity (OR 1.29, 95% CI 1.05-1.59, p = 0.005). Group 2 suspensory femoral fixation had greater pivot shift laxity (OR 1.26, 95% CI 1.01-1.58, p = 0.02) than Group 1 compression femoral fixation. Group 2 compression femoral fixation also had more anterior knee laxity (OR 1.25, 95% CI 1.03-1.52, p = 0.01) than Group 1 compression femoral fixation and higher failure rates based on initial (OR 1.69, 95% CI 1.18-2.4, p = 0.002) and final (OR 1.89, 95% CI 1.32-2.71, p = 0.0003) subject number. Failure rate for HT compression femoral fixation was greater than suspensory femoral fixation based on initial (OR 2.08, 95% CI 1.52-2.84, p < 0.0001) and final (OR 2.26, 95% CI 1.63-3.16, p < 0.0001) subject number. Overall, QT autografts had less pivot shift laxity and lower failure rates based on final subject number than HT autografts. Compression QT autograft femoral fixation had lower pivot shift laxity than suspensory HT autograft femoral fixation. Compression QT autograft femoral fixation had less anterior knee laxity and lower failure rates than compression HT autograft femoral fixation. Suspensory HT autograft femoral fixation had lower failure rates than compression HT autograft femoral fixation. Greater knee laxity and failure rates may be related to a combination of HT autograft diameter and configuration (tissue quality and dimensions, strands, bundles, and suturing method) variability and fixation mode. Level IV.

Allograft Use Results in Higher Re-revision Rate for Revision Anterior Cruciate Ligament Reconstruction.

Background:The literature on revision anterior cruciate ligament (ACL) reconstruction (ACLR) outcomes is generally sparse, but previous studies have demonstrated that autograft use results in improved sports function and patient-reported outcome measures compared with allograft. However, knowledge is still lacking regarding the impact of graft type on rates of re-revision.Purpose:To investigate the clinical outcomes and failure rates of revision ACLRs performed with either allograft or autograft.Study Design:Cohort study; Level of evidence, 3.Methods:A search of the Danish Knee Ligament Reconstruction Registry identified 1619 revision ACLRs: 1315 were autograft procedures and 221 were allograft procedures (type of graft was not identified for 83 procedures). Clinical outcomes after 1 year were reported via the Knee injury and Osteoarthritis Outcome Score (KOOS), the Tegner activity score, and an objective knee stability measurement that determined side-to-side differences in instrumented sagittal knee laxity. Failure was determined as re-revision. Outcomes for revision were provided for the full life of the registry, up to 10 years.Results:The re-revision rate was significantly higher for allograft compared with autograft (12.7% vs 5.4%; P < .001), leading to a hazard ratio for re-revision of 2.2 (95% CI, 1.4-3.4) for allografts compared with autografts when corrected for age. At 1-year follow-up, objective knee stability was significantly different (2.1 ± 2.1 mm for allograft vs 1.7 ± 1.8 mm for autograft; P = .01), and the KOOS subscale scores for symptoms, pain, activities of daily living, sports, and quality of life were 67, 76, 84, 49, and 46 for allograft and 67, 78, 84, 51, and 48 for autograft, respectively, with no difference between groups.Conclusion:In this observational population-based study, the ALCR re-revision rate was 2.2 times greater for allograft compared with autograft procedures. Allograft was associated with greater knee laxity at 1-year follow-up. However, subjective clinical outcomes and knee function were not inferior for allograft patients. These results indicate that autograft is a better graft choice for revision ALCR.

Greater knee laxity after primary ACL reconstruction is associated with subsequent contralateral ACL injury in younger patients

Greater knee laxity after primary ACL reconstruction is associated with subsequent contralateral ACL injury in younger patients

Relaxin Influences Knee Laxity Changes Across the Menstrual Cycle

Greater knee laxity is associated with an increased risk for anterior-cruciate ligament (ACL) injury, particularly in women. Research suggests that the hormone relaxin may influence the structural integrity of the ACL, rendering a weaker and more lax ligament. PURPOSE: To assess the impact of relaxin on knee laxity once progesterone and testosterone (potential endocrine antagonists) are accounted for. METHODS: College-aged females (166.0±5.7cm, 65.9±8.5kg, 20.8±2.9yr) provided blood samples for the first 6 days of menses and first 10 days of luteal phase of one menstrual cycle. Knee laxity was recorded as anterior knee laxity (AKL; mm), genu recurvatum (GR; °), and general joint laxity (GJL; score, 0-9), and dependent variables were calculated as mean (X), cyclic Δ (max – min), coefficient of variation (CV), and standard deviation (SD). Progesterone (P; ng/ml), testosterone (T; ng/dl), and relaxin (R; pg/ml) were analyzed via ELISA assays. The sum of the 6 greatest hormone concentrations during menses (M) and luteal phase (L) and the change in exposure from M to L (MLΔ) were calculated. Only subjects with captured R and P peak were included in analysis (n=18). M and MLΔ for each hormone were entered into backward stepwise (in: p=.05, out: p=.20) multiple linear regression models to predict each laxity measure. RESULTS: R and P were significantly different between M and L (p<.001, RM=22.2±29.4 vs. RL=147.0±96.3; p<.001, PM=5.8±1.8 vs. PL=89.7±36.6), whereas T was less variable (p=.07, TM=203.8±63.0 vs. TL=222.7±82.6). All laxity showed variation across the menstrual cycle (range [min-max]: AKL=5.9-7.6; GR=2.6-5.6; GJL=.8-2.1). Significant models were observed for GRX (p=.014; R2=.418; GRX=3.501+.1.024RMLΔ-.757RM-.395PMLΔ), GJLMLΔ (p=.044; R2=.253; GJLMLΔ=-.469RMLΔ-.440TM), and GJLX (p=.035; R2=.379; GJLX=-.317RM-.353PM-.440PMLΔ-.507TM). Models for AKLMLΔ, AKLCV, GRΔ, and GJLSD approached significance (all p<.075). CONCLUSION: Once controlling for P and T, R was a significant predictor of knee laxity mean and cyclic changes. These findings would suggest that R, combined with other sex hormones, may affect the structural integrity of the ligament and impact injury risk. Further study is needed to explore potential mechanisms for this association.

Differences in Knee Joint Stabilization Between Children and Adults and Between the Sexes

Background: Differences in knee joint stabilization between children and adults and between the sexes are not fully understood. Purpose: To compare the knee laxity and the dynamic tibial translation between (1) children and adults, (2) girls and boys, and (3) women and men. Study Design: Controlled laboratory study. Methods: Sixty-seven children (aged 8-13 years) and 63 adults (aged 18-30 years) without previous knee injuries participated. Sagittal tibial translation was measured during the instrumented Lachman test at 90 N and 134 N (knee laxity) and during gait (dynamic translation). Tibial translation was recorded with an electrogoniometer. Results: Knee laxity was greater in children than in adults (Lachman test at 90 N: 9.1 ± 2.9 vs 7.3 ± 2.7, respectively; P < .001). In contrast, dynamic tibial translation during gait did not differ between children and adults. Girls and boys did not differ in knee laxity or maximum anterior tibial translation during gait, and men and women did not differ in knee laxity. Women had greater dynamic tibial translation during gait than men (7.8 ± 2.7 vs 5.7 ± 3.0, respectively; P = .004). Conclusion: Children had greater knee laxity than adults, whereas the dynamic tibial translation did not differ. In adults, knee laxity did not differ between the sexes, but dynamic tibial translation was greater in women. Clinical Relevance: Children and men had less dynamic tibial translation during gait in proportion to their maximum knee laxity. The observed less dynamic tibial translation in children and adult men might be related to their reduced risk of sustaining an anterior cruciate ligament injury.

Diagnostic Value of Knee Arthrometry in the Prediction of ACL Strain During Landing

Objectives:Excessive knee joint laxity may decrease overall joint stability and increase the risk of anterior cruciate ligament (ACL) injury during high risk activities. Despite the frequent clinical use of knee arthrometry, as an accurate and valid method for evaluation of knee laxity, no data exists to correlate instrumented laxity measures and ACL strain during dynamic high-risk activities. The purpose of this study was to evaluate relationships between instrumented anterior knee laxity measurements and ACL strain during simulated bi-pedal landing (as an identified high-risk injurious task). We hypothesized that a strong correlation would be observed between ACL strain and arthrometry displacement, and that specimens with greater anterior knee laxity would demonstrate increased peak ACL strain during landing.Methods:20 cadaveric lower limbs (46±6 years, 10 female and 10 male) were tested using a CompuKT knee arthrometer to measure anterior knee joint laxity. Each specimen was tested under four continuous cycles of A-P shear force (±134 N) applied to the tibial tubercle. To quantify ACL strain, a DVRT displacement transducer was arthroscopically placed on the ACL (AM-bundle), and specimens were retested. Subsequently, bi-pedal landing from 30 cm was simulated on a subset of 14 specimens (45±5 years, 6 female and 8 male) using a novel custom-designed drop-stand. Paired sample t-tests, and a general linear model were used to evaluate changes in joint laxity and ACL strain. Results:During simulated drawer tests, 134 N of applied anterior drawer load produced an average 3.1±1.1 mm peak anterior tibial translation and 4.9±4.3% peak ACL strain. Anterior drawer load was a significant determinant of anterior tibial translation (p<0.0005) and peak ACL strain (p=0.02). A strong correlation (r=0.78, P<0.0005) was observed between anterior tibial translation and ACL strain during simulated drawer tests. Cadaveric simulations of landing produced an average 4070±732 N axial impact load representing the generated ground reaction force during landing following a jump. Simulated landing significantly increased peak anterior tibial translation to 10.4±3.5 mm and peak ACL strain to 6.8+2.8 % (p<0.0005) compared to pre-landing conditions. Impact-induced anterior tibial translation was a significant factor in peak ACL strain (p=0.001). Strong correlations were observed between peak ACL strain during landing and anterior tibial translation quantified by knee arthrometry (Figure 1). Conclusion:This work represents the first cadaveric study to establish a strong correlation between arthrometrically measured anterior knee joint laxity and peak ACL strain during dynamic landing (as a high-risk injurious condition). Experimental findings support the tested hypothesis, as a strong correlation between arthrometry displacement collected during laxity tests and concurrent calculated ACL strain was demonstrated. Instrumented measures of anterior knee laxity were predictive of peak ACL strain during landing, while specimens with greater knee laxity demonstrated higher levels of peak ACL strain during landing. Considering ACL strain as an established quantifiable measure of ACL injury risk, current findings highlight the importance of instrumented anterior knee laxity assessments as a potential indicator of ACL injury risk in addition to its clinical utility in the evaluation of ACL integrity.

Rehabilitation adherence and anterior cruciate ligament reconstruction outcome

This study examined the relationship between adherence to postoperative physical therapy and outcome after surgical reconstruction of the anterior cruciate ligament (ACL) of the knee in a sample of 72 men and 36 women. Indices of adherence were obtained during the first 6 weeks of postsurgical rehabilitation. Outcome measures were administered before surgery and approximately 6 months after surgery. Results of a canonical correlation analysis indicated a statistically significant association between the adherence variables and the outcome variables (r = 0.56, p < 0.05). Greater attendance at rehabilitation sessions and more favourable practitioner ratings of adherence during rehabilitation sessions were associated with fewer self-reported knee symptoms and greater knee laxity. The findings highlight the complex nature of the adherence – outcome relationship.