Effect of ankle and knee position on tension in the Achilles tendon.

The purpose of this study was to evaluate the relative contributions of ankle and knee position to tension in the Achilles tendon and to determine whether there exists a position of plantarflexion at which the passive tensioning effect of knee extension is eliminated. Seven matched pairs of fresh-frozen cadaver lower extremities were tested. A buckle transducer was used to measure forces in the tendon throughout the full range of knee motion, with the hindfoot fixed. Positioning the hindfoot in 20 degrees to 25 degrees of plantarflexion effectively eliminates tension in the Achilles tendon, regardless of knee position. This information is directly applicable both to the nonoperative treatment of ruptures of the Achilles tendon employing a short leg cast and to surgical repairs, in which tension must be controlled precisely.

Bone mineral content of the spine and proximal femur in female patients with hip fracture.

Measurement of bone density in the spine and hip by quantitative computed tomography (QCT) and dual photon absorptiometry (DPA) was performed in 36 women with hip fracture. Hip density by DPA was determined at three anatomic subregions of the hip. Comparison to normals revealed an average decrease in hip bone density by 15% below controls. Spine density measurements were not significantly different from that of controls. Correlations of hip and spine densities varied by hip subregion. This study demonstrated that bone density measurement methods and measurement at one axial site may not accurately reflect bone density at appendicular subregions.

Operative treatment of syndesmotic disruptions without use of a syndesmotic screw: a prospective clinical study.

A new protocol for the selected omission of transsyndesmotic fixation in Weber class C ankle fractures was prospectively evaluated in 21 consecutive patients. As proposed in a previous cadaveric study (J. Bone Joint Surg., 71A:1548-1555, 1989), the protocol suggested that transsyndesmotic fixation was not required if (1) rigid bimalleolar fracture fixation was achieved or (2) lateral without medial fixation was obtained (i.e., with accompanying deltoid tears) if the fibular fracture was within 4.5 cm of the joint. According to this protocol, only 3 of 21 patients (14%) required transsyndesmotic fixation. Ten of the patients who did not receive transsyndesmotic fixation underwent pronation-external rotation stress radiographs in a fashion analogous to the previous cadaveric study. At 1- to 3-year follow-up, no stress (N = 10) or static view (N = 18) widening of the mortise or syndesmosis was seen in any patient, which supports (with the above guidelines) a limited, rather than routine, use of supplemental transsyndesmotic fixation. Clinical results from this prospective study seem to substantiate previously proposed biomechanical guidelines for the selected omission of transsyndesmotic fixation. Given these guidelines, transsyndesmotic fixation was unnecessary in many cases and the need can be determined before surgery by assessing the integrity of the deltoid ligament and level of the fibular fracture.

A prospective and blinded investigation of magnetic resonance imaging of the knee. Abnormal findings in asymptomatic subjects.

To evaluate magnetic resonance imaging (MRI) of meniscal, ligamentous, and bony abnormalities in patients without clinical symptoms, scans were performed on 74 asymptomatic volunteers without histories or symptoms of knee injury. Before review by three radiologists in an independent and blinded fashion, the scans were mixed with 26 MRI scans from symptomatic patients. Sixteen percent of the asymptomatic volunteers had meniscal abnormalities consistent with a tear. The prevalence of MRI findings of a meniscal tear increased from 13% in individuals younger than 45 years of age to 36% in those older than 45. An additional 30% of the volunteers showed meniscal abnormalities consisting of a linear area of increased MR signal not communicating with a meniscal edge, which was not interpreted to represent a tear. The high incidence of abnormal MRI findings in asymptomatic subjects underscores the danger of relying on a diagnostic test without careful correlation with clinical signs and symptoms. These findings also emphasize the importance of access to relevant clinical data when interpreting MRI scans of the knee.

Posterior radial head dislocation without ulnar fracture.

Posterior radial head dislocation without an ulnar fracture in an adult is a rare injury. The pathology is often unrecognized initially. The patient's resultant elbow motion becomes severely compromised. Prompt diagnosis and reduction of the dislocation yield excellent results. A review of the biomechanical studies of the elbow ligaments enables us to propose a pathophysiological model of this injury, and a case report and review of the literature are presented.

MR scanning of the acutely injured knee: sensitive, but is it cost effective?

Although magnetic resonance (MR) imaging has been established as an accurate diagnostic modality for knee pathology, the cost-effectiveness of this test is not known. In this investigation, we formulated a mathematical equation to assess cost-effectiveness and then used this formula to evaluate the use of knee MR as a diagnostic modality in acute knee injuries. We analyzed 105 consecutive MR scans performed at an imaging center with a diverse referral base, and identified 63 patients who had had symptoms for less than 6 months. Based on average regional medical costs, we calculated that diagnostic arthroscopy is more cost-effective than MR if 78% of the scanned patients eventually undergo arthroscopy. In our study population, 87% had arthroscopy after the MR scan. Therefore, in this patient cohort representing a diverse orthopedic community, arthroscopy alone would have been more cost-effective. Careful analysis in this type of cost-benefit framework would be beneficial and may lead to the establishment of objective criteria by which MR can be used in the most cost-effective manner.

Mechanical considerations for the syndesmosis screw. A cadaver study.

The purpose of this study was to examine the mechanical necessity of using a syndesmosis screw to supplement rigid internal fixation of the fibula and medial malleolus in the treatment of pronation-external rotation fractures. The legs of thirty embalmed and five fresh cadavera were dissected and mounted through the tibia to a frame so that multiple radiographs could be made with a constant relationship between the specimen and the x-ray apparatus. A standardized pronation-external rotation load was applied to the foot, and widening of the syndesmosis was studied on mortise radiographs that were made after each experimental step. On the basis of previous investigations, we developed a model for pronation-external rotation injuries that included disruption of the syndesmosis and interosseous membrane up to the level of the fibular fracture. Accordingly, multiple repaired fibular fractures could be simulated at several levels in the same specimen by incremental proximal division of the interosseous membrane. Specimens were separated into two groups. Group I consisted of thirteen specimens in which the deltoid ligament, syndesmosis, and interosseous membrane were serially sectioned in 1.5-centimeter increments. Group II (ten sections) was subjected to the same protocol, except that the deltoid ligament was kept intact until the final step. The five fresh specimens were sectioned in the same way as those in Group I. In Group I, since the simulated pronation-external rotation injury included a deltoid tear, rigid medial fixation was not possible; accordingly, there was rigid fibular fixation only.(ABSTRACT TRUNCATED AT 250 WORDS)

Retinyl acetate-induced arthritis in C3H-A(vy) mice.

Severely impaired musculoskeletal mobility in C3H-A(vy) mice was noted during a pharmacologic trial evaluating the antitumorigenic properties of retinyl acetate (RAc). To determine the etiology of this impairment, we studied 103 female C3H-A(vy) mice that were fed RAc in daily doses of 75-300 micrograms or placebo and were killed after 3-16 months. Whole-body radiographs and histologic sections of the hindlimbs were scored for presence and severity of arthritis. C3H-A(vy) mice treated with RAc in any dose had a significantly higher incidence of arthritis than placebo-treated mice. Histologic evidence of enthesopathic disease closely paralleled the radiographic changes and ranged from small enthesophytes at tendinous and capsular insertions to complete periarticular bony bridging. Articular cartilage was not grossly affected. The incidence and severity of arthritis were significantly correlated with the total dose of RAc administered. The bony metaplasia induced by RAc was similar to the pathologic changes caused by other retinoids. This model may be useful for studying the pathogenesis of periarticular bone formation in diffuse idiopathic skeletal hyperostosis and related syndromes.