Biomedical subjects

David C Pollock

Publications and source records attributed to David C Pollock.

3 recordsLinked to original sources

PubMed2006

When computer-assisted knee replacement is the best alternative.

We studied whether computer-assisted surgery could properly align total knee arthroplasty when traditional instrumentation was not possible or appropriate. We identified 16 patients (18 knees) who we believed could not be treated using traditional instrumentation because of posttraumatic femoral deformity, retained femoral hardware, a history of osteomyelitis, or severe cardiopulmonary disease. Computer-assisted surgery was successfully used in 17 knees; we were unable to accurately register the hip in one morbidly obese patient. We judged the overall mechanical axis of the limb using computer-assisted surgery acceptable in 16 of 17 knees. One patient with a major posttraumatic biplane deformity had an overall mechanical axis in 4 degrees of varus. Computer-assisted navigation seemed helpful in difficult situations where accurate alignment remains crucial, yet traditional instrumentation is not applicable.

Arthroplasty, Replacement, Knee↗

PubMed2002

Interobserver and intraobserver variability in radiographic assessment of osteolysis.

This study quantified the variability associated with diagnosing periprosthetic osteolysis from the radiographs of total hip arthroplasty patients. Four joint arthroplasty surgeons independently assessed radiographs of 60 patients for evidence of osteolysis in different zones. The surgeons agreed on the presence of lesions in at most 57% of the zones. kappa coefficients, used to quantify the extent of agreement among the surgeons, denoted poor interobserver reproducibility (kappa =.28 to.44). Intraobserver reliability-determined by comparing 2 reviews of the same radiographs done by 1 surgeon 2 weeks apart-was moderate to excellent (kappa =.48 to.84). We also compared the results from the most recent radiograph with those from a time series. Agreement improved when a series was reviewed. Reliable comparisons cannot be made with osteolysis rates reported by different observers. In the research setting, osteolysis rates are more reliable if they are determined by a single reviewer whose intraobserver variability has been reported. In assessing a patient for osteolysis, it is more accurate to analyze a series of radiographs than the most recent radiograph.

Arthroplasty, Replacement, Hip↗

PubMed2002

Synovial entrapment: a complication of posterior stabilized total knee arthroplasty.

BACKGROUND: We observed a complication of posterior stabilized total knee arthroplasty involving hypertrophy of tissue proximal to the patella associated with pain during active knee extension from 90 degrees of flexion. The purpose of this paper was to describe synovial entrapment and to determine if design features of the prosthesis predispose patients to the complication. METHODS: Between April 1990 and June 1999, we performed 459 consecutive posterior stabilized primary total knee arthroplasties using three prosthetic designs with different femoral intercondylar geometries. We identified twenty-six patients (twenty-seven knees) in whom arthroscopic débridement of the knee or open arthrotomy with débridement of the knee had been subsequently performed because of a diagnosis of synovial entrapment. We reviewed the records of these patients to identify the knee components that had been used and the symptoms and conditions that necessitated additional treatment. RESULTS: Symptoms (grating, crepitation, and pain with active knee extension from 90 degrees) necessitating subsequent débridement occurred in 13.5% (nineteen) of 141 knees treated with the Anatomic Modular Knee-Congruency implant, 3.8% (eight) of 212 treated with the Anatomic Modular Knee-Posterior Stabilized implant, and none of the 106 treated with the Press Fit Condylar Sigma-Posterior Stabilized implant. All patients had difficulty rising from a chair and climbing stairs; however, none had symptoms when standing or walking. No patient had a patellar clunk. The symptoms occurred at a mean of seven months after the arthroplasty in the patients with an Anatomic Modular Knee-Congruency implant and at a mean of twenty months after the arthroplasty in those with an Anatomic Modular Knee-Posterior Stabilized implant. Débridement of the frond-like hypertrophic synovial tissue at the distal aspect of the quadriceps tendon alleviated symptoms in all patients. No nodules were identified during the arthroscopy. CONCLUSIONS: Synovial entrapment is characterized by hypertrophic synovial tissue at the superior pole of the patella. Use of a posterior stabilized femoral component with a proximally positioned or wide femoral box is more likely to result in this complication.

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