Instrumented measurement of anterior-posterior translation in knees with chronic anterior cruciate ligament tear

In vivo laxity of stable versus anterior cruciate ligament-injured knees using a navigation system: a comparative study

We compared antero-posterior translation and internal-external rotation of the tibia in stable knees without anterior cruciate ligament (ACL) injury with those of ACL injured knees using a navigation system and suggest an objective data. Forty-four patients treated for a meniscal tear without ACL injury were allocated to stable group, and 41 patients were allocated to ACL injury group. Antero-posterior displacement and rotation of knees were measured in 0, 30, 60 and 90 degrees of flexion using navigation. Mean anterior displacements were 3.6 +/- 2.0, 6.7 +/- 2.7, 6.0 +/- 2.4 and 4.7 +/- 1.8 mm at 0, 30, 60 and 90 degrees of flexion, respectively, in stable group, and 6.8 +/- 3.6, 14.7 +/- 3.5, 11.9 +/- 4.6 and 8.5 +/- 4.0 mm in ACL injury group. Mean total rotation values were 18.8 +/- 4.5 degrees, 31.4 +/- 4.2 degrees, 30.1 +/- 5.1 degrees and 29.2 +/- 5.9 degrees in stable group and 22.7 +/- 6.9 degrees , 37.6 +/- 5.8 degrees, 34.0 +/- 9.4 degrees and 31.8 +/- 8.8 degrees in ACL injury group. Quantitative values of antero-posterior translations and rotations of stable and ACL injured knees were obtained using a navigation system. The laxity data may be useful to establish the diagnosis of an ACL injury and evaluation of post-operative results.

Isolation and characterization of multipotent stem cells from human cruciate ligaments

OBJECTIVES

Mesenchymal stem cells have great potential for tissue regeneration, and these cells can be harvested from a variety of tissues; however, up to now it has not been clear whether stem cells could be isolated from cruciate ligaments of the knee joint. The aim of our study was to isolate and characterize stem cells from both anterior and posterior cruciate ligaments (ACL and PCL) of humans.

MATERIALS AND METHODS

Cruciate ligaments were obtained from patients receiving total knee arthroplasty for advanced osteoarthritis and plastic-adherent cells were serially passaged. In vitro chondrogenic, osteogenic and adipogenic abilities of the cells were evaluated by reverse transcriptase-polymerase chain reaction and histological study. Karyotyping and surface immunophenotyping of the cells were performed.

RESULTS

It was found that a population of ligament-derived cells could be expanded and subcultured extensively. These cells were able to differentiate into osteoblasts, chondrocytes and adipocytes under appropriate inductions. Their phenotypic characteristics were similar to those of bone marrow mesenchymal stem cells. Karyotyping was normal after serial passage.

CONCLUSIONS

In summary, our study demonstrates that human multipotent stem cells can be isolated and expanded from human ACL and PCL, which are easily obtained from patients following total knee or cruciate ligament reconstructive surgery. Self-renewal and mesodermal differentiation potential of these cells make them a viable alternative source for use in regenerative medicine.

Knee-laxity measurements examined by a left-hand- and a right-hand-dominant physiotherapist, in patients with anterior cruciate ligament injuries and healthy controls

The purpose of the study was to analyse and compare KT-1000 knee laxity as examined by a left-hand- and a right-hand-dominant physiotherapist in a group of patients with an anterior cruciate ligament (ACL) injury and a group of patients, 2 years after ACL reconstruction. The other aim was to measure and analyse knee laxity in a group of persons without any known knee problems. A cross-sectional examination of two groups of patients pre-operatively and post-operatively after ACL reconstruction and examination of healthy controls on two different occasions was performed. Fifty-three patients who were scheduled for ACL reconstruction and 39 patients who attended a 2-year follow-up examination were included in the study. In the ACL-deficient group, 32 patients had a right-sided ACL injury and 21 patients a left-sided ACL injury. The corresponding figures in the post-operative group were 21 patients with a right-sided ACL injury and 18 patients with a left-sided ACL injury. Twenty-eight healthy persons without any known knee problems served as controls. One left-hand- and one right-hand-dominant experienced physiotherapist performed all the examinations. To be able to evaluate the intra and inter-reliability of the examiners the controls were examined at two occasions. The left-hand-dominant physiotherapist measured significantly higher absolute laxity values in the left knee, both injured and non-injured ones, compared with the right-hand-dominant physiotherapist. This was found irrespectively of whether the patients belonged to the ACL deficient or the post-operative group. In the healthy control group, the right-hand-dominant physiotherapist measured significantly higher knee-laxity values in the right knee compared with the left-hand-dominant physiotherapist. Correspondingly, the left-hand-dominant physiotherapist measured significantly higher knee laxity values in the left knee. We conclude that KT-1000 arthrometer laxity measurements can be affected by the hand dominance of the examiner. This might affect the reliability of KT-1000 arthrometer measurements. Level of evidence is II.

Right and left knee laxity measurements: a prospective study of patients with anterior cruciate ligament injuries and normal control subjects

PURPOSE

The purpose of this study was to analyze and compare knee laxity in a group of patients with a unilateral right anterior cruciate ligament (ACL) rupture and a group of patients with a unilateral left ACL rupture. Another goal was to analyze and compare the knee laxity of the right and left knees in a group of persons without any known knee problems.

TYPE OF STUDY

Prospective examination of the same patients preoperatively and 2 years after the reconstruction with examination of the healthy controls at 2 different occasions.

METHODS

Group A was composed of 41 patients with a right-sided chronic ACL rupture, and group B was composed of 44 patients with a left-sided chronic ACL rupture. All patients underwent an arthroscopic ACL reconstruction using patellar tendon autograft. Group C was composed of 35 persons without any known knee problems. One experienced physiotherapist performed all the KT-1000 measurements and the clinical examinations.

RESULTS

Group A displayed an increased difference in side-to-side laxity between the injured and non-injured side compared with group B in terms of both anterior and total knee laxity. This difference was found to be statistically significant preoperatively (P =.01, anterior; P =.001, total) and at follow-up evaluation 2 years after the index surgery (P =.008, anterior; P =.006, total). In group C, a significant increase was seen in absolute anterior and total laxity in the right knee compared with the left knee when 2 repeated measurements were performed (P <.0001 and P =.003, anterior; P <.0001 and P =.001, total).

CONCLUSIONS

The KT-1000 arthrometer revealed a significant increase in laxity measurements in right knees compared with left knees. This difference was found both preoperatively and postoperatively in patients undergoing ACL reconstruction. The same thing was found in a group of persons without any known knee problems.

LEVEL OF EVIDENCE

Level II.

Aggressive quadriceps loading can induce noncontact anterior cruciate ligament injury

BACKGROUND

The force responsible for noncontact anterior cruciate ligament (ACL) injuries remains controversial. The patella tendon to tibial shaft angle causes an anterior tibial shear force with quadriceps activation.

HYPOTHESIS

An aggressive quadriceps contraction can injure the ACL.

METHODS

The authors characterized noncontact ACL injury and kinematics with aggressive quadriceps loading. Thirteen fresh-frozen knees were potted in a jig held in 20 degrees of flexion while a 4500 N quadriceps contraction was simulated. Knee kinematics were recorded. A KT-1000 arthrometer and a simulated active quadriceps test assessed anterior displacement. Statistics were performed using paired t tests and 1-way analysis of variance.

RESULTS

Kinematics revealed the following mean values: anterior displacement, 19.5 mm; valgus, 2.3 degrees; and internal rotation, 5.5 degrees. Mean KT-1000 and active quadriceps test differences were 4.0 mm and 2.7 mm, respectively (statistically significant P =.002 and P =.002). Six knees showed gross ACL injury at the femoral insertion. Based on ACL injury, KT-1000 differences were statistically significant (P =.029).

CONCLUSIONS

Aggressive quadriceps loading, with the knee in slight flexion, produces significant anterior tibial translation and ACL injury. This suggests that the quadriceps is the intrinsic force in noncontact ACL injuries, producing a model for further investigation.

Good muscle performance does not compensate instability symptoms in chronic anterior cruciate ligament deficiency

A total of 167 patients with documented anterior cruciate ligament deficiency was examined preoperatively with laxity and isokinetic muscle strength measurements. Functional evaluation with Lysholm knee and Tegner activity level scores were done. Antero-posterior (AP) knee laxity correlated negatively with Tegner activity level (NS), and insignificantly with Lysholm knee score. A marginal correlation was found between the Lysholm score and muscle strength. Patients were divided into four groups depending on whether their AP laxity was greater or less than 20 mm and whether their quadriceps strength was greater or less than 85% of their control knee. No difference in the Lysholm or Tegner scores between the groups was observed. As a conclusion it seems that even a relatively good muscle performance does not compensate severe instability symptoms.