Rotational knee laxity: Reliability of a simple measurement device in vivo

<p>Abstract</p> <p>Background</p> <p>Double bundle ACL reconstruction has been demonstrated to decrease rotational knee laxity. However, there is no simple, commercially-available device to measure knee rotation. The investigators developed a simple, non-invasive device to measure knee rotation. In conjunction with a rigid boot to rotate the tibia and a force/moment sensor to allow precise determination of torque about the knee, a magnetic tracking system measures the axial rotation of the tibia with respect to the femur. This device has been shown to have acceptable levels of test re-test reliability to measure knee rotation in cadaveric knees.</p> <p>Methods</p> <p>The objective of this study was to determine reliability of the device in measuring knee rotation of human subjects. Specifically, the intra-tester reliability within a single testing session, test-retest reliability between two testing sessions, and inter-tester reliability were assessed for 11 male subjects with normal knees.</p> <p>Results</p> <p>The 95% confidence interval for rotation was less than 5° for intra-tester, test-retest, and inter-tester reliability, and the standard error of measurement for the differences between left and right knees was found to be less than 3°.</p> <p>Conclusion</p> <p>It was found that the knee rotation measurements obtained with this device have acceptable limits of reliability for clinical use and interpretation.</p

ACL injuries identifiable for pre-participation imagiological analysis: Risk factors

Identification of pre-participation risk factors for noncontact anterior cruciate ligament (ACL) injuries has been attracting a great deal of interest in the sports medicine and traumatology communities. Appropriate methods that enable predicting which patients could benefit from pre- ventive strategies are most welcome. This would enable athlete-specific training and conditioning or tailored equipment in order to develop appropriate strategies to reduce incidence of injury. In order to accomplish these goals, the ideal system should be able to assess both anatomic and functional features. Complementarily, the screening method must be cost-effective and suited for widespread application. Anatomic study protocol requiring only standard X rays could answer some of such demands. Dynamic MRI/CT evaluation and electronically assisted pivot-shift evaluation can be powerful tools providing complementary information. These upcoming insights, when validated and properly combined, envision changing pre-participation knee examination in the near future. Herein different methods (validated or under research) aiming to improve the capacity to identify persons/athletes with higher risk for ACL injury are overviewed.

Experimental loss of menisci, cartilage and subchondral bone gradually increases anteroposterior knee laxity

Purpose: Anteroposterior knee stability is a relevant factor for the decision-making process of various surgical procedures. In degenerative joints when the implantation of unicompartimental prostheses or corrective osteotomies of the limb are planned, the integrity of the anteroposterior stability with an intact ACL has been regarded as a necessary prerequisite. We hypothesise that joint degeneration, however, may influence the anteroposterior knee laxity. Therefore, we set out to test this hypothesis simulating a progressively ‘degenerated’ joint in an experimental cadaveric setting. Methods: Twelve intact transfemorally resected Thiel-fixated cadaver knee joints were divided into 2 groups for manipulation in the medial or lateral compartment. In each knee, we performed (1) unilateral total meniscectomy; (2) simulation of advanced osteoarthritis, by unilateral total cartilage debridement; (3) simulation of a unilateral tibial impression fracture, by resection of 5 mm of the tibial plateau; (4) transection of the ACL. The KT-1000 arthrometer was used to measure the extent of anteroposterior translation at 30° of knee flexion. Results: The mean value for tibial anteroposterior translation before intervention was 3.2 mm (SD: ±0.8). The mean translation after each intervention was 4.6 mm (SD: ±0.9; +44%; n.s.) after meniscectomy, 5.9 mm (SD: ±1.5; +84%; P < 0.05) after cartilage debridement, 8 mm (SD: ±1.5; +150%; P < 0.01) after bone debridement, and finally 9.7 mm (SD: ±2.2; +203%; P < 0.05) after resection of the ACL. There were no significant differences between the medial and lateral compartment. Conclusion: In absence of massive osteophytes or capsular shrinkage, rapid loss of meniscus, cartilage and particularly loss of subchondral bone may result in a massive increase in anteroposterior translation, mimicking a tear of the ACL. In such a situation, a false positive impression of a ligamentous injury may arise, and decision making is falsely directed away from totally or partially knee joint-preserving procedures. Therefore, in degenerate joints, clinical evaluation of anteroposterior stability should rather rely on the presence of a firm stop than an overall increased joint translation

Postoperative Lateral Ligamentous Laxity Diminishes with Time After TKA in the Varus Knee

For successful TKA, good soft tissue balance is one of the most important factors; however, it is unknown whether the coronal balance immediately after surgery is maintained with time. We hypothesized, if neutral mechanical alignment was achieved at the time of TKA, some degree of lateral ligamentous laxity could be accepted and the laxity would diminish with time. To confirm this hypothesis, we posed two scientific questions: (1) Does the coronal ligament balance measured immediately after TKA change with time? (2) Does the degree of preoperative varus alignment correlate with the lateral or medial ligamentous laxity observed after TKA? We measured coronal lateral or medial ligamentous laxity in 71 knees with varus deformities immediately after surgery and at 3, 6, and 12 months thereafter. The mean mechanical axis was 15.9° varus preoperatively and 0.4° varus postoperatively. The mean medial ligamentous laxity was relatively constant postoperatively from immediately after surgery to 12 months. However, the mean lateral ligamentous laxity was as much as 8.6° immediately after surgery and decreased to 5.1° at 3 months. The lateral ligamentous laxity immediately after surgery correlated with the preoperative varus mechanical axis. Our data show residual lateral ligamentous laxity observed in preoperative varus deformity may be corrected spontaneously after TKA