From 1979 to 1984, 27 skiers who were either present or past members of the United States Ski Team or professional skiers had 30 ACL tears that were repaired primarily. Only two of the repairs were augmented with autogenous patellar tendon grafts. Five patients had complete knee dislocations, including tears of both cruciate ligaments. Nineteen patients had a concomitant extraarticular iliotibial band tenodesis. Twenty-seven knees (24 patients) were followed an average of 57.6 months postoperatively. Recreational skiing was resumed at 5.4 months on average, and in ski racing and pivot-requiring sports all but three patients resumed participation at an average of 9.1 months. In 78% of the knees there was pain-free function. Mild pain was reported in 19%, the majority of which (4/5) was related to vigorous activity. Of the total, only two knees were reported to have a sensation of giving way. On clinical examination 85% (23/27) had normal pivot shift examination with no evidence of abnormal motion. Four percent (1/27) had a 1+ test and 11% (3/27) had "glides." Arthrometer measurements revealed an average of 7.76 mm anterior displacement with 20 pounds of force on the knee with an ACL repair as compared to 5.56 mm on the uninjured knee. The laxity measurements of knees with repaired ACLs fell within the range reported for uninjured knees in the normal population. Five patients had reinjuries to the ACL at an average time of 28 months postoperatively, with two of five undergoing rerepair. Only one patient had an iliotibial band tenodesis to supplement the original ACL repair.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

An in vivo analysis of the effect of transcutaneous electrical stimulation of the quadriceps and hamstrings on anterior cruciate ligament deformation.

Transcutaneous electrical muscle stimulation (TEMS) has been advocated as a method to rehabilitate the postoperative ACL repaired/reconstructed lower extremity. Isolated quadriceps contraction can potentially disrupt the ACL repair/reconstruction; to minimize this risk simultaneous quadriceps and hamstring stimulation has been used. This study measured the in vivo deformation of the ACL during TEMS of the quadriceps and hamstrings. Six legs in four Rhesus monkeys were immobilized in 0 degrees, 45 degrees, and 90 degrees of flexion in neutral rotation using a Hoffman frame and pins placed through the proximal femur and distal tibia. The hamstrings and quadriceps muscles were stimulated with a dual channel electrical stimulator individually and simultaneously at each point of flexion, and ACL deformation was measured using a Hall effect device placed on the anterior medial fibers of the ACL. The following conclusions were made: 1) Isolated quadriceps contraction produces ACL elongation at 0 degrees and 45 degrees of knee flexion and produces ACL shortening at 90 degrees of knee flexion. 2) Isolated hamstrings contraction produces ACL shortening at 45 degrees and 90 degrees of knee flexion and negligible effects at full knee extension. 3) It is not possible to simultaneously contract the quadriceps and hamstrings using separate stimulator pads for each muscle group. 4) At 45 degrees of knee flexion when the quadriceps muscles are stimulated before the hamstring muscles and simultaneous contraction of both is then sustained, ACL lengthening occurs. 5) When the hamstring muscles are fired before the quadriceps muscles and simultaneous contraction of both is sustained, ACL shortening occurs.

Animals↗

PubMedDate not supplied

A nonparallel, nonisometric synthetic graft augmentation of a patellar tendon anterior cruciate ligament reconstruction. A model for assessment of stress shielding.

The potential for a rigidly fixed synthetic graft placed in the over-the-top position to be stress shielding/stress sharing with the patellar tendon autograft was assessed in a primate model. A patellar tendon autograft was placed anatomically and tensioned at 2 pounds for all of the groups. In the augmented animals, a 30 strand braided graft 10 cm in length of expanded polytetrafluoroethylene was tightened with the knee in full extension. After 6 months of unrestricted cage activity the animals were sacrificed and biomechanical testing performed. The augmented patellar tendon autografts demonstrated less laxity in extension as compared to the autografts alone. A minimal decrease in the load and stiffness to failure for the augmented groups as compared to the nonaugmented knees was noted. However, both the reconstruction groups had a significant decrease in the load to failure at 6 months (50% of the normal ACL). In summary, this study demonstrated that a synthetic graft augmentation can be performed in the over-the-top position and minimize knee laxity, especially during terminal extension. With this technique, the laxity was minimized while the incorporation and strengthening of the biologic autograft occurred at a rate similar to the unaugmented reconstruction.

Animals↗

PubMedDate not supplied

Meniscal regeneration with copolymeric collagen scaffolds. In vitro and in vivo studies evaluated clinically, histologically, and biochemically.

We sought to create a regeneration template for the meniscal cartilage of the knee to induce complete meniscal regeneration, and to develop the technique for implanting the prosthetic appliance in vivo. We designed a resorbable collagen-based scaffold and conducted in vitro and in vivo studies. In vivo, the scaffold was implanted in the knees of immature swine and mature canines and evaluated clinically, histologically, and biochemically. Because the canine stifle joint meniscus is more clinically relevant to the human meniscus, this paper emphasizes those results. We studied 24 mixed breed dogs (14 males and 10 females) with an average weight of 25.5 kg (range, 20 to 35) that were obtained from a USDA-licensed supplier. The dogs were deemed clinically and radiographically skeletally mature. None of the dogs had a preexisting knee joint abnormality. All dogs underwent an 80% subtotal resection of the medial meniscus bilaterally. A collagen template was implanted in one stifle (N = 24). The contralateral side served as a control: 12 dogs had a total resection alone and the other 12 dogs had an immediate replantation of the autologous meniscus. Results were tabulated at 3, 6, 9, and 12 months. At final evaluation, before the animals were euthanized, the results were submitted for statistical analysis as well as histologic and biochemical analyses. The results demonstrated that a copolymeric collagen-based scaffold can be constructed that is compatible with meniscal fibrochondrocyte growth in vitro and in vivo, that does not inhibit meniscal regeneration in an immature pig, and that may induce regeneration of the meniscus in the mature dog.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Measurements of the intercondylar notch by plain film radiography and magnetic resonance imaging.

The purpose of this investigation was twofold. In Part I, we determined the accuracy of morphometric analysis of the knee using magnetic resonance imaging and plain film radiography. The results of Part I validated the accuracy of magnetic resonance measurements and its superiority over plain film measurements. In Part II, we evaluated knee morphometry in 20 asymptomatic athletes with chronic anterior cruciate ligament insufficiency to determine if any predisposing factors to anterior cruciate ligament disruption could be detected. With our analysis, we could detect no predisposing factors to explain the anterior cruciate ligament disruption in the cohort group.

Anterior Cruciate Ligament Injuries↗

PubMedDate not supplied

Effects of patellar tendon adhesion to the anterior tibia on knee mechanics.

The effects of patellar tendon adhesion on the knee extensor mechanism and on the kinematics and contact areas for both the patellofemoral and tibiofemoral joints were determined for five cadaveric knees in an open kinetic chain testing configuration. Patellar tendon adhesion decreased the distance from the inferior patellar pole to the tibial tuberosity, effectively creating patella infera. When compared with the controls, knees with adhesion had medial and distal translation of the patella, as well as increased patellar flexion. Although the patellar articular contact location shifted distally, the overall contact area did not change significantly. For the tibia, adhesion resulted in significant medial, proximal, and anterior translation, and internal rotation. Adhesion also resulted in a posterior shift of the tibial contact location. For the extensor mechanism, adhesion decreased the knee extension force created by the quadriceps muscle on the tibia, indicating a decrease in the effective moment arm of the extensor mechanism. Furthermore, as a result of patellar tendon adhesion, the angle formed by the quadriceps and patellar tendons decreased, suggesting an increase in patellofemoral joint reaction force with adhesion. The increased patellofemoral joint reaction force and the altered contact location may be related to anterior knee pain after knee trauma and knee surgery. Therefore, patients should be observed for subtle patella infera, which may indicate patellar tendon adhesion.

Aged↗

PubMedDate not supplied

Pull-out strength and stiffness of meniscal repair using absorbable arrows or Ti-Cron vertical and horizontal loop sutures.

We tested pull-out strength and linear stiffness of meniscal repair using bioabsorbable arrows and vertical and horizontal loop sutures in fresh-frozen bovine lateral menisci. In phase I, menisci repaired either with 2-0 Ti-Cron vertical or horizontal loop suture, or 10-, 13-, or 16-mm Meniscus Arrows were loaded to failure at 12.5 mm/sec. In phase II, we examined the number of barbs engaged and angle of insertion using 10- and 13-mm arrows. Pull-out strengths of both suture repair groups were significantly higher than those of the arrow groups. Vertical loop sutures were significantly stiffer than horizontal sutures and 10-mm arrows. In phase II, the mean ultimate load to failure for the 10-mm arrows was 35.1 N, significantly stronger than in phase I (18.5 N); however, stiffness remained low (7.9 N/mm). Five arrows in the 13-mm group were inserted parallel to the tibial surface and showed no significant difference from phase I. Five arrows were inserted at more than a 30 degrees angle. This group was significantly weaker than in phase I. Single vertical loop suture showed the highest overall pull-out strength. Although weaker than sutures, arrows should provide sufficient stability for meniscal healing. The number of barbs engaged and angle of insertion are critical.

Absorbable Implants↗

PubMedDate not supplied

Anterior cruciate ligament injury incidence among male and female professional alpine skiers.

A retrospective review of anterior cruciate ligament injuries among professional alpine skiers was performed to compare sex-related differences in injury incidence. We screened 7155 ski patrollers or instructors (4537 men and 2618 women) for knee injuries before each ski season between 1991 and 1997. Screening involved a ski history questionnaire, a knee injury history questionnaire, and a knee physical examination. Any patient with an equivocal Lachman or pivot shift test was evaluated by KT-1000 arthrometry and excluded from the study if the manual maximum side-to-side difference was 3 mm or more. Thus, the study population was limited to subjects with intact anterior cruciate ligaments. Skiers injured during the study were identified through mandatory workers' compensation claims. Each injured skier was reevaluated using an injury questionnaire and physical examination. The men skied an average of 110 days per year (499,070 skier-days) and the women skied an average of 87 days per year (227,766 skier-days). Thirty-one skiing-related anterior cruciate ligament injuries were diagnosed, 21 in men and 10 in women. The incidence of ACL disruption was 4.2 injuries per 100,000 skier-days in men and 4.4 injuries per 100,000 skier-days in women. These data suggest that the incidences of anterior cruciate ligament injuries among male and female professional alpine skiers are similar.

Adult↗

PubMedDate not supplied

Rehabilitation of acute injuries of the anterior cruciate ligament.

The major controversy about the anterior cruciate ligament (ACL) is the appropriate time for use of terminal knee extension and exercises that place a subluxing force. Recent studies have delineated the area in which the quadriceps mechanism provides a subluxing force on the tibia and across the knee joint. An active rehabilitation program encourages progressive recovery of function while protecting the knee against subluxing forces. The program includes rehabilitation for nonsurgically treated but torn cruciate injuries, and injuries of the ACL repaired by various surgical operations.

Humans↗