Mechanisms of anterior cruciate ligament injury.

This study examined the mechanisms of anterior cruciate ligament (ACL) injury. In the first part of the study, using a comprehensive, standardized questionnaire, 89 athletes (100 knees) were interviewed about the events surrounding their ACL injury. A noncontact mechanism was reported in 71 (72%) knees and a contact injury in 28 (28%) knees; one patient was unsure if there was any contact. Most of the injuries were sustained at footstrike with the knee close to full extension. Noncontact mechanisms were classified as sudden deceleration prior to a change of direction or landing motion, while contact injuries occurred as a result of valgus collapse of the knee. Hamstring flexibility parameters revealed a statistically higher level of laxity in the injured athletes compared with a matched group of 28 controls. In the second part of the study, videotapes of 27 separate ACL disruptions were reviewed and confirmed that most noncontact injuries occur with the knee close to extension during a sharp deceleration or landing maneuver. Because the knee is in a position to allow the extensor mechanism to strain the ACL and maximum, eccentric muscle force conditions usually apply, the quadriceps may play an important role in ACL disruption. Passive protection of the ACL by the hamstring muscles may be reduced in patients with above-average flexibility.

Autogenous tendon graft substitution for absent knee joint meniscus: a pilot study.

The purpose of this pilot study was to explore the potential of an autogenous tendon graft to substitute for an absent human knee joint meniscus. Based on the results of animal studies and human reports, it was hypothesized that autogenous tendon tissue would substitute for human knee joint meniscus: maintain mechanical integrity, convert to fibrocartilage, preserve the joint compartment, and provide symptomatic relief for the patient. Five patients, 2 men and 3 women, average age 41 years, had surgical absence of the lateral meniscus, genu valgum, and severe degenerative arthritis of the lateral compartment, but a stable knee. All patients were offered alternative treatments: do nothing, medication, arthroscopic debridement, osteotomy, and knee replacement. The operations were performed by arthroscopy. An accompanying arthroscopic debridement procedure was performed in the same compartment. In 4 cases, the donor graft was the semitendinosus tendon. In 1, the patellar tendon was used because the semitendinosus had been previously used in an anterior cruciate ligament reconstruction. Four of the 5 patients had a second-look arthroscopy and biopsy between 9 and 24 months. There was partial physical integrity to the tendon graft. The tendon graft did not completely convert to fibrocartilage. The joint surface was not preserved. Only 1 patient had minimal clinical improvement; the others were not improved. No patient was made worse. One patient had a total knee replacement 1 year later. Another had a knee fusion after 4 years. All other patients are considering future reconstructive surgery. The autogenous tendon graft as used in this pilot study was not successful as a substitute for an absent meniscus. The hypothesis was not realized. The observations from this pilot study should be helpful in future study protocol design.

Shoulder injuries from alpine skiing and snowboarding. Aetiology, treatment and prevention.

There has been a decrease in the overall injury rate and the rate of lower extremity injuries for alpine skiing, with a resultant increase in the ratio of upper extremity to lower extremity injuries. Upper extremity injuries account for 20 to 35% of all injuries during alpine skiing and nearly 50% of all injuries during snowboarding. The most common upper extremity injuries during skiing are sprain of the thumb metacarpal-phalangeal joint ulnar collateral ligament, and the most common in snowboarding is wrist fracture. Shoulder injuries from skiing and snowboarding have been less well characterised. With the increased ratio of upper to lower extremity injuries during alpine skiing and the boom in popularity of snowboarding, shoulder injuries will be seen with increasing frequency by those who care for alpine sport injuries. Shoulder injuries account for 4 to 11% of all alpine skiing injuries and 22 to 41% of upper extremity injuries. The rate of shoulder injuries during alpine skiing is 0.2 to 0.5 injuries per thousand skier-days. During snowboarding, shoulder injuries account for 8 to 16% of all injuries and 20 to 34% of upper extremity injuries. Falls are the most common mechanism of shoulder injury, in addition to pole planting during skiing and aerial manoeuvres during snowboarding. Common shoulder injuries during skiing and snowboarding are glenohumeral instability, rotator cuff strains, acromioclavicular separations and clavicle fractures. Less common shoulder injuries include greater tuberosity fractures, trapezius strains, proximal humerus fractures, biceps strains, glenoid fractures, scapula fractures, humeral head fractures, sterno-clavicular separations, acromion fractures and biceps tendon dislocation. Prevention of shoulder injuries during skiing and snowboarding may be possible through interventions in education and technique, conditioning and equipment and environment.

Anterior cruciate ligament reconstruction. Bone-patella tendon-bone versus semitendinosus anatomic reconstruction.

In this article, the long term (2-10 years; mean, 4.8 years) followup results of two reconstructive procedures for the anterior cruciate ligament are compared. The bone-patella tendon-bone (with interference fit fixation) was performed on 69 knees, and the semitendinosus anatomic reconstruction was performed on 68 knees, in a population of 76 men and 52 women (age range, 15-60 years; average, 31 years). The patients in the two groups showed no difference in subjective results or activity level and no significant difference to manual testing. The semitendinosus procedure group had a slightly higher KT manual maximum failure rate than the patella tendon group (17% versus 11%). Arthrometric stability did not show deterioration, but patient satisfaction decreased in those patients who had meniscectomies. Both procedures showed satisfactory results during the long term followup. However, if the secondary restraints are compromised, the stiffer bone-patella tendon-bone construct is preferred for reconstruction of the chronic anterior cruciate ligament deficient knee.

Meniscal fixation with an absorbable staple. An experimental study in dogs.

An absorbable staple for meniscal fixation was developed and evaluated in an in vivo canine study. The staple consisted of two rigid barbed legs, made of a copolymer of polyglycolic acid and polylactic acid, connected by a flexible suture made of the same absorbable material. The staple was developed for arthroscopic use, eliminating the risk of nerve or vascular injuries associated with suture fixation. Eighty-two mongrel dogs underwent meniscal repair in this study, which was performed in two sequential parts. An incision was made in the medial meniscus at the peripheral third and was fixed with either the staple or with a single 3-0 PDS suture. The animals from the first part of the study, in which the biocompatibility of a prototype staple design, was evaluated were sacrificed at 3 days, 2 weeks, 6 weeks, 3 months, and 9 months. Those from the second part of the study, in which an improved staple design of the same material, was evaluated were sacrificed at 6 weeks, 4 months, and 1 year. The operated menisci were either examined histologically or were mechanically tested for tensile strength. Absorption of the staple began by 3 months and was almost complete by 1 year. Mechanically, the staple provided greater tensile strength augmentation of the meniscus than suture fixation for up to 4 months. In the long term, there was no difference between the staple and suture in enhancement of healing.

Shoulder injuries during alpine skiing.

We retrospectively reviewed alpine skiing injuries at a destination ski resort during three seasons to characterize the incidence and types of shoulder injuries. A total of 3451 injuries in 3247 patients were reviewed. The overall injury rate was 4.44 injuries per 1000 skier-days. Injuries to the upper extremity represented 29.1% (N = 1004) of all alpine ski injuries. Injuries involving the shoulder complex (393 injuries in 350 patients) accounted for 39.1% of upper extremity injuries and 11.4% of all alpine skiing injuries. The rate of shoulder injury was 0.51 injuries per 1000 skier-days. Patients with shoulder injuries had a mean age of 35.4 years, and the male-to-female ratio of these patients was 3:1. Falls represented the most common mechanism of shoulder injury (93.9%) in addition to collisions with skiers (2.8%), pole planning (2.3%), and collisions with trees (1%). The most common shoulder injuries were rotator cuff strains (24.2%), anterior glenohumeral dislocations or subluxations (21.6%), acromioclavicular separations (19.6%), and clavicle fractures (10.9%). Less common shoulder injuries included greater tuberosity fractures (6.9%), trapezius muscle strains (6.4%), proximal humeral fractures (3.3%), biceps tendon strains (2.3%), glenoid fractures (1.5%), scapular fractures (1%), humeral head fractures (1%), sternoclavicular separations (0.5%), an acromial fracture (0.3%), a posterior glenohumeral dislocation (0.3%), and a biceps tendon dislocation (0.3%).

A surgical algorithm for treatment of cystic degeneration of the Meniscus.

Cystic degeneration of the meniscus is not uncommon. Recent reports suggest that most (or all) meniscal cysts are associated with a meniscal tear, and that the treatment of choice is arthroscopic partial meniscectomy with cyst decompression. This report describes a case of a symptomatic lateral meniscal cyst that was suspected clinically and confirmed by magnetic resonance imaging, but was not associated with a meniscal tear at arthroscopy. Open cyst extirpation and peripheral meniscal repair were performed to maximize preservation of meniscal tissue. A clinical algorithm is presented for management of meniscal cysts.

Behavior of sutures used in anterior cruciate ligament reconstructive surgery.

This study was performed to determine the material properties of sutures commonly used in orthopedic surgery in order to allow selection of the most appropriate one for securing a hamstring or quadriceps tendon graft in anterior cruciate ligament (ACL) reconstruction. Three suture materials (number 5 Ticron, number 5 Ethibond, and 5 mm Mersilene tape) were tested. The ultimate tensile load (UTL) with and without a knot, modulus of elasticity, effect of conditioning on the behavior of the suture, and plastic deformation were determined for each suture. Prior conditioning significantly improved the plastic deformation characteristics of all three sutures. Mersilene possessed the highest UTL both with and without knots, and its plastic deformation was significantly lower than that of Ticron or Ethibond. We feel that these characteristics make it the best suture for use in securing hamstring or tendon grafts in ACL surgery. Because of the high UTL achieved by Mersilene tape in the knotted surgical loop construct (nearly 500 N), it may be possible to achieve fixation integrity approaching that of interference fixation with bone blocks.

Ski injury statistics, 1982 to 1993, Jackson Hole Ski Resort.

A retrospective analysis was conducted on injury statistics compiled over 12 seasons, from 1982 to 1993 (2.55 million skier-days), at a Wyoming ski resort. The population at risk was determined by ticket sales per year. A total of 9749 skiing injuries was indexed by anatomic region and severity according to diagnosis on initial evaluation. Injury rates were then analyzed as a function of time. The injury rate remained constant at 3.7 injuries per 1000 skier-days during the 12 seasons. The rate of lower extremity to upper extremity injury decreased from 4:1 to 2:1 during the study period (P < 0.03). The ankle injury rate also decreased with time (P < 0.04). Ulnar collateral ligament sprains make up 7% of all injuries. Knee sprains in general account for 30% of all injuries. The incidence of anterior cruciate ligament tears increased as a function of time (P < 0.04) and accounted for 16% of all skiing injuries during the study period. The medial collateral ligament sprain was the most common injury, making up 18% of skiing injuries. Forty-seven snowboard injuries from the 1992 to 1993 season are also presented. Our injury statistics mirror those currently reported in North America, except our data reflect a higher incidence of knee sprains.

Augmentation of meniscal repairs with cyanoacrylate glue.

Cyanoacrylate glues are biodegradable, bacteriostatic, hemostatic adhesives which have been used experimentally in surgical procedures on many tissues. This study evaluates the efficacy of cyanoacrylate glues used for in vitro bovine meniscus repair. Our hypothesis was that a local adhesive might improve fixation of meniscus tears reapproximated with suture, or obviate the need for suture. Three high-viscosity flexible cyanoacrylate glues were tested and their tensile strengths compared to those of suture alone and suture augmented with glue. The flexible formulation enables the glue to deform with the meniscus during movement of the knee joint. Bovine meniscus tissue was used as the model to compare the tensile strength at the meniscus repair site using the 300 cps glue in combination with 3-0 prolene suture, 300 cps cyanoacrylate glue alone, and suture alone. Twenty specimens were included in each repair group, and the peak load to failure was normalized for surface area and subjected to analysis of variance. Results of the analysis showed that the peak load to failure of the combination of cyanoacrylate glue plus suture was significantly higher than that of glue alone (P < .0001), but not significantly higher than that of suture alone (P = .18). However, in tissues repaired with suture, tissue separation at the tear site was noted almost immediately after distraction started, as a result of the elasticity of the suture. The combination of cyanoacrylate glue plus suture provided the maximum tensile strength before tissue separation. Because tissue separation may interfere with the meniscal healing process, glue used in combination with suture appears to offer some advantage mechanically.(ABSTRACT TRUNCATED AT 250 WORDS)

Graft-bone healing of a meniscus autograft anchored in bone tunnels.

UNLABELLED: This experiment was designed to histologically study the attachment process between a meniscus autograft and bone when the meniscus autograft is placed within bone at its anterior and posterior horns. In order to provide a time-sequenced histologic picture, a canine model was used. The study group consisted of eleven mature canines that underwent complete medial meniscectomy of the stifle joint followed by immediate replacement using an autogenous tissue meniscal scaffold fashioned from the lateral fascia of the thigh. The graft was fixed in bone tunnels at the anterior and posterior horns. One animal was sacrificed immediately after implantation, one at 10 days, three at 28 days, two at 3 months, two at 6 months, and two at nine months. Photographs were taken and histologic sections through bone tunnels were analyzed. The graft consisted of rolled tensor fascia and exogenous clot. RESULTS: The attachment process begins with the invasion of an interface of well vascularized, primitive mesenchymal cells between the soft-tissue graft and the host bone. Histologic evidence of collagenous attachment to bone is visible at one month after graft implantation. Collagen organization with increasing soft tissue attachment to bone is progressive throughout the nine months time frame of the study. The attachment points become increasingly more continuous from three to six months. By six months, the attachment points are confluent and continuous throughout the depths of the tunnel.

An electromyographic study of arm muscles during climbing.

Upper extremity muscle injuries from rock climbing are common. Knowledge of the activity of specific muscles during climbing may allow the development of training programs to reduce these injuries. This study evaluated the electrical activity of the first interosseous (IN), brachioradialis (BR), flexor digitorum superficialis (FD), and biceps brachii (BB) muscles in seven climbers by integrated electromyography (IEMG) during finger-tip pull-ups. The climbers, with forearms pronated, performed three consecutive pull-ups. Each pull-up consisted of: (1) hanging using four fingers of each hand, (2) pull-up to maximum elbow flexion, (3) slow return to starting position. The IEMG during maximum voluntary contraction (MVC) was obtained for each muscle separately, and the IEMG was normalized to MVC. During hanging, FD showed the highest normalized IEMG (0.64 +/- 0.20). During pull-up, the highest IEMG was produced by FD (0.69 +/- 0.25) and BR (0.67 +/- 0.19), while BB showed only 0.33 +/- 0.12 and IN 0.09 +/- 0.06. During lowering, FD again had the highest IEMG (0.74 +/- 0.24), while the EMG from BR was decreased to 0.42 +/- 0.14 and BB to 0.15 +/- 0.15. BR and BB showed an abrupt peak in EMG during pull-up and lowering, as opposed to FD which remained constantly highly activated, which suggests that FD does not contribute to elbow flexion even though it crosses the elbow joint. The high activation of FD and BR may explain their elevated incidence of injury during climbing. Thus, a reduction in climbing-related muscle injuries may be achieved by a training program that emphasizes conditioning of the BR and FD muscles.

Topographical anatomy of the intercondylar roof. A pilot study.

Anatomical features of the intercondylar roof with respect to the native anterior cruciate ligament and proposed substitute ligament attachment sites in anterior cruciate ligament reconstructive surgery were investigated. Using cadaveric knees and K wires, radiographs were obtained with markers placed on the roof and the tibial and femoral attachment sites. In the knees studied, the intercondylar roof was V shaped with distinct anterior and posterior limbs. The posterior limb corresponded to the radiographic line commonly called Blumensaat's line. The anterior limb was oriented 25 degrees more vertical than the posterior limb and impinged on the anterior cruciate ligament in extension. In this pilot study, estimates of the degree of impingement in full extension were made by drawing lines representative of 10-mm grafts at selected sites on lateral radiographs. A graft placed at the central portion of the native femoral site to the normal tibial site did not impinge, while a graft placed at the traditional femoral site to an anteromedial tibial site impinged as much as 8 mm throughout its entire extent. This pilot study presents preliminary, provocative information suggesting that the intercondylar roof is actually V shaped and that substitute ligaments placed at attachment sites commonly used today may impinge over most of their length.

Graft isometricity in unitunnel anterior cruciate ligament reconstruction: analysis of influential factors using a radiographic model.

A radiographic model was developed to investigate the influence of three surgical variables on the change in attachment point distance (CAPD) of a hypothetical graft using the unitunnel technique of anterior cruciate ligament (ACL) reconstruction. Using three different femoral target points, we tested the hypothesis that varying the angle of knee flexion between 70 degrees and 110 degrees and varying the tibial starting point over a 4-cm range do not result in a significant variation in CAPD. We also tested the hypothesis that the CAPD from 0 degrees to 135 degrees is greater than the CAPD from 0 degrees to 90 degrees. There was a statistically significant correlation (r = 0.8465, P < 0.0001) between radiographically estimated and isometer-measured values of CAPD. The tibial starting point and the femoral target point were found to affect the CAPD significantly (P < 0.005). A more proximal tibial starting point was associated with a lower CAPD. Both the center of the anatomic femoral attachment of the ACL, and a point 1 mm medial to the junction of the roof and lateral wall of the femoral intercondylar notch and 6 mm anterior to its posterior margin, were associated with lower CAPD values than a target point 5 mm superior and posterior to the center of the femoral ACL attachment. The angle of knee flexion did not significantly affect the CAPD. The CAPD [0 degrees-135 degrees] was significantly greater than the CAPD [0 degree-90 degrees] for all combinations of variables (P < 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)

The medial patellofemoral ligament revisited: an anatomical study.

The purpose of this study was to provide a comprehensive description of the anatomy of the medial patellofemoral ligament (MPFL). The anterior and medial aspects of 4 unpreserved and 16 preserved cadaveric human knees were dissected with particular attention being paid to the relationship of the various layers to one another and to the place of the MPFL within these layers. We confirmed that the MPFL is a distinct structure lying within layer II. Its bulk varies considerably between individuals but not from side to side in a given individual. The visualisation, attachments, and gross morphology of the ligament are described. The attachments of the MPFL and the orientation of its fibres suggest that it may have a role in limiting lateral excursion of the patella. The common attachment of the tendon of the vastus medialis muscle and the ligament to the superomedial patella suggests that there may be a dynamic element to such a stabilising function.

Osseous injury associated with acute tears of the anterior cruciate ligament.

Multiplanar spin-echo magnetic resonance imaging was performed on 54 patients with acute complete anterior cruciate ligament tears. Imaging was done within 45 days of index anterior cruciate ligament injury. Spin-echo T1- and T2-weighted images were used to determine the lesion morphology and location. Only the T2-weighted sagittal images were used for the incidence assessment; T2-weighted spin-echo imaging reflects free water shifts and best indicates the acute edema and inflammatory changes from injury. Eighty-three percent (45 of 54) of the knees had an osseous contusion directly over the lateral femoral condyle terminal sulcus. The lesion was highly variable in size and imaging intensity; however, the most intense signal was always contiguous with the subchondral plate. Posterolateral joint injury was seen in 96% (43 of 45) of the knees that had a terminal sulcus osseous lesion determined by magnetic resonance imaging. This posterolateral lesion involves a spectrum of injury, including both soft tissue (popliteus-arcuate capsuloligamentous complex) and hard tissue (posterolateral tibial plateau) injuries. The consistent location of the osseous and soft tissue injuries underscores a necessary similar mechanism of injury associated with these acute anterior cruciate ligament tears. Based on these characteristic findings, several proposed mechanisms of injury are discussed.

Climbing and the older athlete.

Climbing may be considered appropriate for the older athlete. The requisites, cardiovascular and musculoskeletal fitness, can be attained through training; the skills can be acquired through schools or guide services. Inherent risks can enhance the enjoyment. The motivational psychology for climbing usually reflects positive qualities and attitudes toward life and the environment. With good health, the recreation of climbing can be enjoyed well into the seventh decade of life. Climbing may not be for everyone, but the physical and physiologic benefits, as well as the challenges, are available to the older athlete.