Biomechanical evaluation of intra-articular and extra-articular procedures in anterior cruciate ligament reconstruction: a finite element analysis.

BACKGROUND: Intra-articular techniques (single and double bundles) are the most widely used procedures for the anterior cruciate ligament reconstruction. Lemaire introduced in 1967 the extra-articular techniques, and combined intra-articular and extra-articular reconstruction, to better restore the stability of the knee. However, the effectiveness of these procedures (intra-articular, extra-articular combined or not with intra-articular) seems to be controversial. METHODS: In the present study, we developed numerical models of a knee joint to evaluate the effects of these different procedures on the kinematics and biomechanics of the knee during an internal rotation test. Six cases were simulated: intact anterior cruciate ligament, intra-articular reconstructed anterior cruciate ligament (single and double bundles), extra-articular reconstructed anterior cruciate ligament alone, and combination of extra- and intra-articular reconstructions. The loading condition was an internal tibial torque of 2 N m at 0 degrees, 15 degrees, 30 degrees and 45 degrees of knee flexion. Internal rotation of the tibia and forces within the grafts and the ligaments were calculated. FINDINGS: This study showed that both single and double bundles intra-articular reconstructions restore similar internal rotation control and biomechanics of the soft structures as the intact anterior cruciate ligament situation. On the other hand, our results indicate that extra-articular reconstruction reduces appreciably the internal rotation and modifies the charges distribution in the soft structures when compared to the intact anterior cruciate ligament. INTERPRETATION: The extra-articular procedure alters the kinematics of the knee, which might overconstraint the ligaments and the femorotibial joints, leading to the failure of the anterior cruciate ligament reconstruction.

A new ambulatory system for comparative evaluation of the three-dimensional knee kinematics, applied to anterior cruciate ligament injuries.

The aim of this study was to develop an ambulatory system for the three-dimensional (3D) knee kinematics evaluation, which can be used outside a laboratory during long-term monitoring. In order to show the efficacy of this ambulatory system, knee function was analysed using this system, after an anterior cruciate ligament (ACL) lesion, and after reconstructive surgery. The proposed system was composed of two 3D gyroscopes, fixed on the shank and on the thigh, and a portable data logger for signal recording. The measured parameters were the 3D mean range of motion (ROM) and the healthy knee was used as control. The precision of this system was first assessed using an ultrasound reference system. The repeatability was also estimated. A clinical study was then performed on five unilateral ACL-deficient men (range: 19-36 years) prior to, and a year after the surgery. The patients were evaluated with the IKDC score and the kinematics measurements were carried out on a 30 m walking trial. The precision in comparison with the reference system was 4.4 degrees , 2.7 degrees and 4.2 degrees for flexion-extension, internal-external rotation, and abduction-adduction, respectively. The repeatability of the results for the three directions was 0.8 degrees , 0.7 degrees and 1.8 degrees . The averaged ROM of the five patients' healthy knee were 70.1 degrees (standard deviation (SD) 5.8 degrees), 24.0 degrees (SD 3.0 degrees) and 12.0 degrees (SD 6.3 degrees for flexion-extension, internal-external rotation and abduction-adduction before surgery, and 76.5 degrees (SD 4.1 degrees), 21.7 degrees (SD 4.9 degrees) and 10.2 degrees (SD 4.6 degrees) 1 year following the reconstruction. The results for the pathologic knee were 64.5 degrees (SD 6.9 degrees), 20.6 degrees (SD 4.0 degrees) and 19.7 degrees (8.2 degrees) during the first evaluation, and 72.3 degrees (SD 2.4 degrees), 25.8 degrees (SD 6.4 degrees) and 12.4 degrees (SD 2.3 degrees) during the second one. The performance of the system enabled us to detect knee function modifications in the sagittal and transverse plane. Prior to the reconstruction, the ROM of the injured knee was lower in flexion-extension and internal-external rotation in comparison with the controlateral knee. One year after the surgery, four patients were classified normal (A) and one almost normal (B), according to the IKDC score, and changes in the kinematics of the five patients remained: lower flexion-extension ROM and higher internal-external rotation ROM in comparison with the controlateral knee. The 3D kinematics was changed after an ACL lesion and remained altered one year after the surgery.

Effects of the posterior cruciate ligament reconstruction on the biomechanics of the knee joint: a finite element analysis.

BACKGROUND: Previous experimental studies have been conducted to evaluate the biomechanical effects of posterior cruciate ligament reconstruction; but no consensus has been reached on the preferred method of reconstruction. METHODS: The 3D finite element mesh of a knee joint was reconstructed from computed tomography and magnetic resonance images. The ligaments were considered as hyperelastic materials. The tibiofemoral and patellofemoral joints were modeled with large sliding contact elements. The 3D model was used to simulate knee flexion from 0 degrees to 90 degrees in four cases: a knee with a "native" posterior cruciate ligament, a resected posterior cruciate ligament, a reconstructed single graft posterior cruciate ligament, and a reconstructed double graft posterior cruciate ligament. FINDINGS: A resected posterior cruciate ligament induced high compressive forces in the medial tibiofemoral and patellofemoral compartments. The pressures generated in the tibiofemoral and patellofemoral compartments were nearly the same for the two reconstruction techniques (single graft and double graft). The single graft resulted in lower tensile stresses inside the graft than for the double graft. INTERPRETATION: Firstly, a resected posterior cruciate ligament should be replaced to avoid excessive compressive forces, which are a source of cartilage degeneration. Secondly, the two types of posterior cruciate ligament reconstruction techniques partially restored the biomechanics of the knee in flexion, e.g. contact pressures were restored for pure flexion of the knee. The reconstruction techniques therefore partially restore the biomechanics of the knee in flexion. A double graft reconstruction is subjected to the highest tensile stresses.

["Isolated" injury of the posterior cruciate ligament. Surgical treatment of isolated posterior cruciate ligament tears: a multicentric retrospective study of 103 patients]. / Traitement chirurgical d'une rupture isolée du ligament croisé postérieur: résultats d'une série rétrospective multicentrique de 103 patients.

PURPOSE OF THE STUDY: We present a retrospective multicentric series of carefully selected patients presenting "isolated" laxity of the posterior cruciate ligament. MATERIAL AND METHODS: The series included 103 patients who were reviewed clinically (with a dedicated review chart) and radiographically with measurement of posterior laxity (Telos 15 kg). RESULTS: In these patients with an isolated injury of the PCL (without associated injury of the peripheral ligament) DISCUSSION: The short follow-up of this series (four years) does not enable an assessment of the risk or benefit of PCL ligamentoplasty for arthrosic knees.

Medial meniscectomy in patients over the age of fifty: a six year follow-up study.

PURPOSE: Meniscectomy in the older patient remains a controversial topic. The aim of our study is to assess the mid-term outcome of arthroscopic partial medial meniscectomy in patients over fifty years of age and attempt to retrospectively identify symptoms and/or findings on examination which can differentiate between non-degenerative medial meniscal tears versus degenerative meniscal changes. MATERIALS AND METHODS: Thirty-two patients over the age of fifty who had undergone arthroscopic medial partial meniscectomy, were reviewed. The average age was 60 (51-74 yrs) and the average follow-up was six years (3-7 yrs). Based upon the intra-operative findings, patients were divided into two groups: (1) non-degenerative meniscal tears (NDM; n = 12) and (2) degenerative meniscal changes (DM; n = 20). Our outcome measurements were with the HSS knee score, a satisfaction score, and weight-bearing X-rays. RESULTS: In the NDM group, eleven patients were rated excellent or good, and one was rated poor. In the DM group, three patients were rated as excellent or good, eight as fair, and nine as poor. The HSS score was 97 +/- 4.6 for the NDM group and 85 +/- 9.5 for the DM group. The average satisfaction score was 9.2 +/- 0.7 (very satisfied) for the NDM group and 5.8 +/- 2.6 (fairly satisfied) for the DM group. There was no significant difference between the NDM and the DM groups with regards to pre-operative symptoms and signs, except for the McMurray sign, which was found to be positive in 83% of NDM cases versus 25% of DM cases (sensitivity = 83%). Using only these data, the McMurray sign was 67% specific for NDM. CONCLUSIONS: Arthroscopic medial meniscectomy in older patients provides 90% good results six years after a non-degenerative meniscal tear, but only 20% of good results after a degenerative meniscal tear. However, based on this study, neither symptoms nor physical examination are able to differentiate between traumatic meniscal tears and degenerative meniscal changes in older patients. A positive McMurray's sign favors the diagnosis of a traumatic tear. However, a specificity of this test of only 67% as shown in our data questions its utility in clinical decision-making.

Stress fracture of the ulna in a professional tennis player using a double-handed backhand stroke.

Stress fractures of the ulna are uncommon injuries, but they have been reported in athletes from various sports. In tennis players stress fractures of the ulna are described exclusively in the nondominant forearm of athletes using a two-handed backhand stroke. We report such a case in a 24-year-old tennis player, with special emphasis on diagnostic imaging, accurate grading of the injury, and specific treatment recommendations.