Biomechanics of calcaneal fractures: a model for the motor vehicle.

Changes in legislation, availability of passive or active restraint systems, or both, together with increased public awareness for safety and the need for use of restraint, have shifted the spectrum of trauma in motor vehicle crashes from the head and torso to other regions. Lower extremity trauma in motor vehicle crashes continues to be a significant problem. The objective of this study was to investigate the biomechanics of the human foot and ankle complex under impact loading and replicate calcaneal fractures routinely seen in motor vehicle crashes. Twenty-two unembalmed cadaver lower extremity specimens were subjected to dynamic loads using a minisled pendulum device. Input and output forces and results of pathologic analysis were obtained using load cell data, radiographs obtained before and after testing, and gross dissection. The intraarticular fracture patterns produced were similar to those seen clinically and described in the literature. Maximum forces ranged from 3.6 to 11.4 kN for the fracture, and 0.5 to 7.3 kN for the nonfracture groups. Logistic regression analysis revealed a 50% probability of calcaneal fracture at 5.5 kN and a 25% probability at 4.0 kN. These studies will lead to an understanding of the tolerance of the lower extremity in sustaining calcaneal fractures under impact. Implications of the work are in the design of crash test dummies, data acquisition, and modifications in motor vehicle design and safety.

Severe heterotopic ossification after arthroscopic acromioplasty: a case report.

Heterotopic ossification is a well-recognized complication of spinal cord injury, closed head injury, total hip arthroplasty, burns, and other trauma and has been observed in various tissues such as muscles, tendons, ligaments, and menisci. Complications of arthroscopic acromioplasty are relatively uncommon and include hematoma, traction neuropathy, infection, acromial fracture, reflex sympathetic dystrophy, and instrument breakage. However, little has been reported on heterotopic ossification of the shoulder, particularly after arthroscopic surgery. Recurrent rotator cuff impingement symptoms caused by small amounts of heterotopic ossification after arthroscopic acromioplasty have been described. We report a case of severe heterotopic ossification about the shoulder after arthroscopic acromioplasty.

Rotator cuff: evaluation with US and MR imaging.

Magnetic resonance (MR) and ultrasound (US) imaging are currently touted for assessment of rotator cuff disease. Optimum clinical imaging techniques include use of (a) a 1.5-T MR imaging unit with small planar coils, proton-density-weighted and T2-weighted fast spin-echo sequences, and 10-12-cm fields of view (yielding 400-470 x 500-625-microm in-plane spatial resolution) and (b) a state-of-the-art commercial US unit with insonation frequencies of 9-13 MHz (yielding 200-400-microm axial and lateral resolution). Proper diagnosis requires familiarity with normal anatomic characteristics and imaging pitfalls. Care must be taken to avoid sonographic tendon anisotropy and MR imaging magic angle effects, which can be misinterpreted as rotator cuff tear. At MR imaging, a complete cuff tear typically appears as either a hyperintense defect or a tendinous avulsion that extends from the bursal to the articular side of the cuff; a partial cuff tear typically appears as a focal hyperintense region that contacts only one surface of the cuff. Complete and partial tears manifest with a wide spectrum of findings at US. MR imaging and US are effective for evaluating rotator cuff injuries, with high reported accuracies for detection of complete tears but more disparate results for detection of partial tears.

Fracture of the proximal tibia after anterior cruciate ligament reconstruction: a case report.

A case of fracture of the proximal tibia at the site of graft harvest for an anterior cruciate ligament reconstruction is reported. This fracture, at the distal edge of the harvest site on the tibial tubercle, was the result of stress concentration at this location. The patient's tibia fracture was treated with a long leg cast and healed without complication. Fracture of the patella at the graft harvest site has been reported as a complication of anterior cruciate ligament reconstruction. This is the first report of a fracture of the tibia at the site of graft harvest.

After the fall: symptoms in bungee jumpers.

A survey of 100 professionally supervised bungee jumpers who used an ankle harness in a single leap from a platform reveals that 42 jumpers had a total of 59 minor medical complaints or symptoms after their jumps. Immediate symptoms included musculoskeletal pain in the ankle, neck, back, and chest, neurologic complaints such as dizziness and headache, and blurred vision. Dizziness was the most common symptom, and neurologic complaints outnumbered musculoskeletal symptoms. All complaints resolved within 1 week of the jump except for lacerations sustained by one person who tried to grab the platform as he was jumping.

In vitro and in vivo MR imaging of hyaline cartilage: zonal anatomy, imaging pitfalls, and pathologic conditions.

Hyaline cartilage plays an essential role in the maintenance of normal synovial joint function by reducing friction and distributing loads. Histologic analysis of hyaline cartilage reveals zonal variation in cellular morphology, proteoglycan concentration, and collagen fiber size and orientation. High-resolution magnetic resonance (MR) imaging reveals an analogous laminar anatomy that is often visible on clinical images obtained with proper attention to technique. In vitro and in vivo pulse sequences show three distinct laminae: a hypointense superficial lamina, a hyperintense intermediate lamina, and a heterogeneous deep lamina that consists of alternating hyperintense and hypointense bands perpendicular to the subchondral bone. Imaging pitfalls include magic angle effects, truncation artifact, partial volume effect, regional anatomic variation, chemical shift, and magnetic susceptibility effects. Pathologic conditions that affect articular cartilage include chondromalacia patellae, osteoarthritis, and localized traumatic lesions. Although detection of early cartilage disease remains elusive, MR imaging can demonstrate intermediate and advanced lesions.

Normal MR imaging anatomy of the elbow.

This article discusses the normal, clinically relevant MR imaging anatomy of the elbow. A compartmental approach is utilized to help simplify this anatomically complex region. Imaging techniques, common anatomic variants, and imaging pitfalls are also briefly discussed.

Diagnosis and treatment of common knee injuries in athletes.

Knee injuries are an all too common occurrence in athletes. Prompt diagnosis, aggressive treatment and rehabilitation is necessary to minimize time away from athletic activity and to maximize function at a competitive level. This article reviews the latest trends in diagnosing and treating common knee injuries in athletes, including ligamentous and meniscal injuries.

Long-term followup of the untreated isolated posterior cruciate ligament-deficient knee.

We evaluated 38 subjects with isolated posterior cruciate ligament-deficient knees at a mean of 13.4 years (range, 5 to 38) after injury to study the occurrence of symptoms, disabilities, and articular degeneration. Each subject completed a standardized questionnaire, physical examination, and had radiographs taken of both knees. Eight (21%) patients had surgeries for meniscal injuries after their posterior cruciate ligament injuries. The mean questionnaire score for function (50-point maximum) was 34.4 +/- 6.5 (SD) for the patients who did have meniscal surgeries versus 40.0 +/- 8.7 for the 30 patients who did not (P = 0.05). Among the 30 patients with isolated posterior cruciate ligament-deficient knees with normal menisci, 24 (81%) had at least occasional pain and 17 (56%) had at least occasional swelling. As time from injury increased, increased articular degeneration on radiographs was seen (P = 0.037). Our study suggests that the prognosis for the isolated posterior cruciate ligament-deficient knee varies. Some patients experience significant symptoms and articular deterioration, while others are essentially asymptomatic and maintain their usual knee function.

Repair of patellar tendon disruptions without hardware.

Acute repair of disruptions of the knee extensor mechanism is indicated to reestablish extensor continuity and allow for early motion. This study reviews the results of acute primary repair of patellar tendon ruptures augmented by a nonabsorbable polyester tape (Mersilene; Ethicon, Inc.) followed by immediate mobilization. Twenty-four patients with disruptions of their patellar tendons were treated using the described technique. The ruptured tendon was initially approximated using an end-to-end suture repair with no. 5 Ticron suture in a whipstitch manner. An O Vicryl suture was used to approximate the free tendon edges. A 5-mm Mersilene tape was then used in a cerclage manner to augment and protect the repair. Postsurgery, passive range of motion (ROM) was begun immediately in the knees with isolated injury or in those patients whose concomitant injuries would allow for early motion. Using clinical and radiographic criteria, follow-up evaluations of 19 patients were performed at an average of 22.4 months. In patients with isolated injuries, active ROM was from 0 degrees extension to 132 degrees flexion (contralateral knee 0-135 degrees). Two patients had prominent knots: in one, the knots were painful and were removed surgically. Six patients developed patellofemoral chondrosis. Five patients had the Mersilene tape tied with the knee in full extension, and all developed patellofemoral pain. The other repairs were done with the knee flexed to 90 degrees before tying; one patient in this group developed patellofemoral symptoms. All patients with isolated injuries have returned to employment. There were no reruptures or infections.(ABSTRACT TRUNCATED AT 250 WORDS)

The basic science of anterior cruciate ligament surgery.

Surgery for ligamentous injuries of the knee continues to be one of the most common procedures performed by orthopaedists. Anterior cruciate ligament (ACL) reconstructions are addressed specifically. Basic science and laboratory research have had a dramatic effect on our understanding of the underlying pathology of the injury, and this information has been used in the development of the clinical procedures most commonly used today. The classic stages of ligament healing are contrasted with the limited potential of the ACL. Surgical options using autografts, allografts, augmentation devices, and primary repair are discussed. Present research is examined for possible future directions in the treatment of ligament injuries.