Measurement of laxity in the anterior cruciate ligament-deficient knee: A comparison of three different methods in vitro

Evaluation of an Unloading Concept for Knee Osteoarthritis: A Pilot Study in a Small Patient Group

Joint compressive forces have been identified as a risk factor for osteoarthritis disease progression. Therefore, unloader braces are a common treatment with the aim of relieving pain, but their effects are not clearly documented in the literature. A knee brace concept was tested with the aim of reducing joint loads and pain in knee osteoarthritis patients by applying an extension moment exclusively during the stance phase. The ideal effects were evaluated during gait based on musculoskeletal modeling of six patients, and experimental tests with a prototype brace were conducted on one patient. The effects were evaluated using electromyography measurements and musculoskeletal models to evaluate the muscle activation and knee compressive forces, respectively. The ideal brace simulations revealed a varying reduction of the first peak knee force between 3.5% and 33.8% across six patients whereas the second peak was unaffected. The prototype reduced the peak vasti muscle activation with 7.9% and musculoskeletal models showed a reduction of the first peak knee compressive force of up to 26.3%. However, the prototype brace increased the knee joint force impulse of up to 17.1% and no immediate pain reduction was observed. The reduction of the first peak knee compressive force, using a prototype on a single patient, indicates a promising effect from an applied knee extension moment for reducing knee joint loads during normal gait. However, further clinical experiments with this brace method are required to evaluate the long-term effects on both pain and disease progression in knee osteoarthritis patients.

Design, Repeatability, and Comparison to Literature Data of a New Noninvasive Device Called "Rotameter" to Measure Rotational Knee Laxity

The present paper deals with the design, the repeatability, and the comparison to literature data of a new measuring device called “Rotameter” to characterize the rotational knee laxity or the tibia-femoral rotation (TFR). The initial prototype P1 of the Rotameter is shortly introduced and then modified according to trials carried out on a prosthetic leg and on five healthy volunteers, leading therefore to an improved prototype P2. A comparison of results obtained from P1 and P2 with the same male subject shows the enhancements of P2. Intertester and intratester repeatability of this new device were shown and it was observed that rotational laxities of left and right knees are the same for a healthy subject. Moreover, a literature review showed that measurements with P2 presented lower TFR values than other noninvasive devices. The measured TFR versus torque characteristic was quite similar to other invasive devices, which are more difficult to use and harmful to the patient. Hence, our prototype P2 proved to be an easy-to-use and suitable device for quantifying rotational knee laxity. A forthcoming study will validate the Rotameter thanks to an approach based on computed tomography in order to evaluate its precision.

Impact of Patient Sex on Clinical Outcomes: Data From an Anterior Cruciate Ligament Reconstruction Registry, 2008-2013

Background:

The Combined Quality Care Anterior Cruciate Ligament registry provides data for clinical research regarding primary anterior cruciate ligament (ACL) surgery.

Purpose:

To explore the data with regard to the clinical outcomes between sexes after ACL reconstruction in a Dutch population.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Data involving patients diagnosed with an ACL tear and eligible for surgery were recorded. Isokinetic muscle strength, functional muscle performance, and anterior-posterior translation of the knee joint were documented preoperatively and at 3, 6, 9, and 12 months postoperatively. Patients completed the Knee Injury and Osteoarthritis Outcome Score (KOOS), Lysholm, and Tegner rating scales during each examination using a web-based questionnaire.

Results:

Approximately 90% of ACL injuries occurred during sport activities. The mean (SD) age at surgery was 28 (11) years for both men and women, and the majority of patients were treated with hamstring tendon autografts (94%). Four percent received bone–patellar tendon–bone autografts, and 2% of the patients received other grafts. Preoperatively, the KOOS, Lysholm, and Tegner scores were significantly higher in males. Twelve months postoperatively, both sexes showed comparable isokinetic strength (P = .336), knee laxity (P = .680), and hop test for distance (P = .122) when comparing the injured with the uninjured side. Self-reported knee function was comparable between sexes as assessed by the KOOS (P = .202), Lysholm (P = .872), and Tegner (P = .767) questionnaires during the 12-month follow-up.

Conclusion:

One year after ACL surgery, all patients had improved greatly, showing only minor differences between sexes. The male group showed slightly better results when evaluating self-reported knee questionnaires. Comparable outcomes and knee function between sexes can therefore be presumed with patients who are treated with hamstring tendon autografts in a Dutch population.

Clinical Relevance:

These results can be used during the clinical evaluation of patients who are eligible for ACL reconstruction.

Bench testing of a knee joint arthrometer

The KT1000 and KT2000 knee joint arthrometers (MEDmetric Corp, San Diego, California) have been shown to overestimate the measurement of knee joint sagittal laxity. The purpose of this study was to investigate the accuracy of the KT arthrometers as measures of anterior and posterior linear displacement. The anterior and posterior linear displacements of 3 KT arthrometers (2 KT1000 arthrometers and 1 KT2000 arthrometer) were compared with the simultaneous displacement measured by a precision linear Vernier Dial Test Indicator (Davenport Ltd, London, United Kingdom). The displacement calculated using the analog output of the KT2000 was also compared with the values on the KT2000 displacement dial. Compared with the Vernier Dial Test Indicator, the KT arthrometers overestimated anterior linear displacement by between 22% and 24%. True anterior displacement for all 3 arthrometers, as recorded by the Vernier Dial Test Indicator, was found by multiplying the KT value by 0.79. When compared with the Vernier Dial Test Indicator, the KT arthrometers underestimated posterior linear displacement by between 18% and 19%. True posterior displacement, as recorded by the Vernier Dial Test Indicator, was found by multiplying the KT1000 value by 1.17 and the KT2000 value by 1.16. The internal apparatus of the KT2000 and KT1000 knee joint arthrometers overestimates anterior displacement and underestimates posterior displacement with a predictable relative systematic error. Future validation studies should use these correction equations to assess the accuracy of the KT arthrometers. Sagittal plane knee laxity measured with the KT devices requires systematic correction for optimal accuracy.

A new diagnostic approach using regional analysis of anterior knee laxity in patients with anterior cruciate ligament deficiency

PURPOSE

The first purpose of this study was to analyze the characteristics of the anterior knee laxity in the three regions of different stiffness in the force-displacement curve, which was obtained from a frequently used arthrometer for quantifying knee joint stability in the patients with anterior cruciate ligament (ACL) rupture and the healthy controls. The second purpose was to compare the characteristics from the regional analysis of the anterior knee laxity between the two subject groups in order to explore proper diagnosis criteria.

METHODS

Seventy-one patients with unilateral ACL tear and eighty healthy controls were enrolled and their anterior knee laxities were tested using the KT-2000 arthrometer. The displacements and stiffness of the three regions were extracted separately and compared between groups to further develop the diagnostic criteria.

RESULTS

The results indicated that the laxity behavior was mostly affected in Region 2 and Region 3 after ACL tear. Two good indicators for ACL tear were found in the receiver operating characteristic (ROC) curve analysis: Region 2 with the displacement larger than 3.7 mm and Region 3 with the stiffness smaller than 22 N/mm. These two criteria provided a better diagnostic accuracy with increased sensitivity.

CONCLUSIONS

The regional analysis method developed in this study could provide more information for understanding the characteristics of the anterior knee laxity and help increase the diagnostic accuracy for ACL rupture.

LEVEL OF EVIDENCE

II.

The effect of medial versus lateral meniscectomy on the stability of the anterior cruciate ligament-deficient knee

BACKGROUND

The pivot shift is a dynamic test of knee stability that involves a pathologic, multiplanar motion path elicited by a combination of axial load and valgus force during a knee flexion from an extended position.

PURPOSE

To assess the stabilizing effect of the medial and lateral meniscus on anterior cruciate ligament-deficient (ACL-D) knees during the pivot shift examination.

STUDY DESIGN

Controlled laboratory study.

METHODS

A Lachman and a mechanized pivot shift test were performed on 16 fresh-frozen cadaveric hip-to-toe lower extremity specimens. The knee was tested intact, ACL-D, and after sectioning the medial meniscus (ACL/MM-D; n = 8), lateral meniscus (ACL/LM-D; n = 8), and both (ACL/LM/MM-D; n = 16). A navigation system recorded the resultant anterior tibial translations (ATTs). For statistical analysis an analysis of variance was used; significance was set at P < .05.

RESULTS

The ATT significantly increased in the ACL-D knee after lateral meniscectomy (ACL/LM-D; P < .05) during the pivot shift maneuver. In the lateral compartment of the knee, ATT in the ACL-D knee increased by 6 mm after lateral meniscectomy during the pivot shift (16.6 +/- 6.0 vs 10.5 +/- 3.5 mm, P < .01 for ACL/LM out vs ACL out). Medial meniscectomy, conversely, had no significant effect on ATT in the ACL-D knee during pivot shift examination (P > .05). With standardized Lachman examination, however, ATT significantly increased after medial but not lateral meniscectomy compared with the ACL-D knee (P < .001).

CONCLUSION

Although the medial meniscus functions as a critical secondary stabilizer to anteriorly directed forces on the tibia during a Lachman examination, the lateral meniscus appears to be a more important restraint to anterior tibial translation during combined valgus and rotatory loads applied during a pivoting maneuver.

CLINICAL RELEVANCE

This model may have implications in the evaluation of surgical reconstruction procedures in complex knee injuries.

Current concepts in instrumented knee-laxity testing

BACKGROUND

Instrumented knee laxity testing devices have been used in both the clinical and research setting to evaluate persons with injuries about the knee. The ability to accurately and reproducibly quantify knee motion has the potential to greatly benefit both clinical practice and research by improving the validity of the research involving treatment of knee-ligament injuries.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A thorough literature review was performed, and a systematic overview is provided evaluating the methods of use and the evidence for the use of instrumented knee laxity testing devices.

RESULTS

Devices that provide measurements of knee laxity have evolved during the past 30 years. The authors describe in detail their proper use and the best estimates of their validity based on clinical studies.

CONCLUSION

The review suggests that the KT-1000 knee arthrometer and the Rolimeter provide best results when testing anterior laxity at the knee, whereas the Telos device is superior for the assessment of posterior laxity.