Sample size and statistical power of randomised, controlled trials in orthopaedics.

We reviewed all 717 manuscripts published in the 1997 issues of the British and American volumes of the Journal of Bone and Joint Surgery and in Clinical Orthopaedics and Related Research, from which 33 randomised, controlled trials were identified. The results and sample sizes were used to calculate the statistical power of the study to distinguish small (0.2 of standard deviation), medium (0.5 of standard deviation), and large (0.8 of standard deviation) effect sizes. Of the 33 manuscripts analysed, only three studies (9%) described calculations of sample size. To perform post-hoc power assessments and estimations of deficiencies of sample size, the standard effect sizes of Cohen (small, medium and large) were calculated. Of the 25 studies which reported negative results, none had adequate power (beta < 0.2) to detect a small effect size and 12 (48%) lacked the power necessary to detect a large effect size. Of the 25 studies which did not have an adequate size of sample to detect small differences, the average used was only 10% of the required number Our findings suggest that randomised, controlled trials in clinical orthopaedic research utilise sample sizes which are too small to ensure statistical significance for what may be clinically important results.

A meta-analysis of thromboembolic prophylaxis in total knee arthroplasty.

Deep venous thrombosis (DVT) is common in total knee arthroplasty (TKA). Because of the rarity of the most serious outcomes, most randomized controlled trials lack the power to analyze these outcomes. A meta-analysis was performed for agents used in DVT prophylaxis in TKA employing a Medline literature search. Study inclusion criteria were randomized controlled trials comparing prophylactic agents in elective TKA with mandatory screening for DVT by venography. Fourteen studies (3,482 patients) met inclusion criteria. For total DVT, all agents except dextran and aspirin protected significantly better than placebo (P < .0001). For proximal DVT rates, low-molecular-weight heparin was significantly better than warfarin (P = .0002). There was a trend that aspirin was better than warfarin (P = .0106). No significant difference was found for symptomatic pulmonary embolism, fatal pulmonary embolism, major hemorrhage, or total mortality.

Treatment of osteoporosis: are physicians missing an opportunity?

BACKGROUND: Medical treatment of women with established osteoporosis may decrease the incidence of future fractures. Postmenopausal women who have sustained a distal radial fracture have decreased bone-mineral density and nearly twice the risk of a future hip fracture. The purpose of this study was to evaluate the adequacy of diagnosis and treatment of osteoporosis in postmenopausal women following an acute fracture of the distal part of the radius. METHODS: A retrospective cohort study was performed with use of a claims database that includes more than three million patients, from thirty states, enrolled in multiple health plans. All women, fifty-five years of age or older, who sustained a distal radial fracture between July 1, 1994, and June 30, 1997, were identified in the database. Only patients with at least six months of continuous and complete medical and pharmaceutical health-care coverage from the date of the fracture were enrolled, to ensure that all health-care claims would be captured in the database. This cohort of patients was then evaluated to determine the proportion who had undergone either a diagnostic bone-density scan or treatment with any recommended medication for established osteoporosis (estrogen, a bisphosphonate, or calcitonin) within six months following the fracture. RESULTS: A search of the database identified 1,162 women, fifty-five years of age or older, who had a distal radial fracture. Of these 1,162 patients, thirty-three (2.8 percent) underwent a bone-density scan and 266 (22.9 percent) were treated with at least one of the medications approved for treatment of established osteoporosis. Twenty women had both a bone-density scan and drug treatment. Therefore, only 279 (24.0 percent) of the 1,162 women who sustained a distal radial fracture underwent either diagnostic evaluation or treatment of osteoporosis. There was a significant decrease in the rate of treatment of osteoporosis with increasing patient age at the time of the fracture (p < 0.0001). CONCLUSIONS: Current physician practice may be inadequate for the diagnosis and treatment of osteoporosis in postmenopausal women who have sustained a distal radial fracture.

A meta-analysis of thromboembolic prophylaxis following elective total hip arthroplasty.

BACKGROUND: Although several agents have been shown to reduce the risk of thromboembolic disease, there is no clear preference for thromboembolic prophylaxis in elective total hip arthroplasty. The purpose of this study was to define the efficacy and safety of the agents that are currently used for prophylaxis against deep venous thrombosis -- namely, low-molecular-weight heparin, warfarin, aspirin, low-dose heparin, and pneumatic compression. METHODS: A Medline search identified all randomized, controlled trials, published from January 1966 to May 1998, that compared the use of one of the prophylactic agents with the use of any other agent or a placebo in patients undergoing elective total hip arthroplasty. For a study to be included in our analysis, bilateral venography had to have been performed to confirm the presence or absence of deep venous thrombosis. Fifty-two studies, in which 10,929 patients had been enrolled, met the inclusion criteria and were included in the analysis. The rates of distal, proximal, and total (distal and proximal) deep venous thrombosis; symptomatic and fatal pulmonary embolism; minor and major wound-bleeding complications; major non-wound bleeding complications; and total mortality were determined for each agent in each study. The absolute risk of each outcome was determined by dividing the number of events by the number of patients at risk. A general linear model with random effects was used to calculate the 95 percent confidence interval of risk. A crosstabs of study by outcome was performed to test homogeneity (ability to combine studies). The risk of each outcome was compared among agents and between each agent and the placebo. RESULTS: With prophylaxis, the risk of total (proximal and distal) deep venous thrombosis ranged from 17.7 percent (low-molecular-weight heparin) to 31.1 percent (low-dose heparin); the risk with prophylaxis with any agent was significantly lower than the risk with the placebo (48.5 percent) (p < 0.0001). The risk of proximal deep venous thrombosis was lowest with warfarin (6.3 percent) and low-molecular-weight heparin (7.7 percent), and again the risk with any prophylactic agent was significantly lower than the risk with the placebo (25.8 percent) (p < 0.0001). Compared with the risk with the placebo (1.51 percent), only warfarin (0.16 percent), pneumatic compression (0.26 percent), and low-molecular-weight heparin (0.36 percent) were associated with a significantly lower risk of symptomatic pulmonary embolism. There were no significant differences among agents with regard to the risk of fatal pulmonary embolism or of mortality with any cause. The risk of minor wound-bleeding was significantly higher with low-molecular-weight heparin (8.9 percent) and low-dose heparin (7.6 percent) than it was with the placebo (2.2 percent) (p < 0.05). Compared with the risk with the placebo (0.28 percent), only low-dose heparin was associated with a significantly higher risk of major wound-bleeding (2.56 percent) and total major bleeding (3.46 percent) (p < 0.0001). CONCLUSIONS: The best prophylactic agent in terms of both efficacy and safety was warfarin, followed by pneumatic compression, and the least effective and safe was low-dose heparin. Warfarin provided the lowest risk of both proximal deep venous thrombosis and symptomatic pulmonary embolism. However, there were no identifiable significant differences in the rates of fatal pulmonary embolism or death among the agents. Significant risks of minor and major bleeding complications were observed with greater frequency with certain prophylactic agents, particularly low-molecular-weight heparin (minor bleeding) and low-dose heparin (both major and minor bleeding).

Unusual case of septic arthritis of the hip: spread from adjacent adductor pyomyositis.

Distinguishing intracapsular and extracapsular hip infections may be clinically difficult. Because of this difficulty in diagnosis, the spread of an extracapsular infection into the hip joint may be missed and lead to significant joint destruction. The case of a patient who suffered from the spread of adductor pyomyositis to the hip joint is reported. The delay in diagnosis of an intracapsular hip infection led to significant intra-articular destruction and ultimately necessitated a Girdlestone resection arthroplasty. The patient's hip function was salvaged with a total hip arthroplasty. The presence of an extracapsular hip infection should mandate serial physical examinations and aggressive evaluation to rule out intracapsular spread. A delay in diagnosis of an intracapsular hip infection can lead to catastrophic results.

The adequacy of medical school education in musculoskeletal medicine.

A basic familiarity with musculoskeletal disorders is essential for all medical school graduates. The purpose of the current study was to test a group of recent medical school graduates on basic topics in musculoskeletal medicine in order to assess the adequacy of their preparation in this area. A basic-competency examination in musculoskeletal medicine was developed and validated. The examination was sent to all 157 chairpersons of orthopaedic residency programs in the United States, who were asked to rate each question for importance and to suggest a passing score. To assess the criterion validity, the examination was administered to eight chief residents in orthopaedic surgery. The study population comprised all eighty-five residents who were in their first postgraduate year at our institution; the examination was administered on their first day of residency. One hundred and twenty-four (81 per cent) of the 154 orthopaedic residency-program chairpersons who received the survey responded to it. The chairpersons rated twenty-four of the twenty-five questions as at least important. The mean passing score (and standard deviation) that they recommended for the assessment of basic competency was 73.1 +/- 6.8 per cent. The mean score for the eight orthopaedic chief residents was 98.5 +/- 1.07 per cent, and that for the eighty-five residents in their first postgraduate year was 59.6 +/- 12 per cent. Seventy (82 per cent) of the eighty-five residents failed to demonstrate basic competency on the examination according to the chairpersons' criterion. The residents who had taken an elective course in orthopaedic surgery in medical school scored higher on the examination (mean score, 68.4 per cent) than did those who had taken only a required course in orthopaedic surgery (mean score, 57.9 per cent) and those who had taken no rotation in orthopaedic surgery (mean score, 55.9 per cent) (p = 0.005 and p = 0.001, respectively). In summary, seventy (82 per cent) of eighty-five medical school graduates failed a valid musculoskeletal competency examination. We therefore believe that medical school preparation in musculoskeletal medicine is inadequate.

Impingement syndrome following total shoulder arthroplasty and humeral hemiarthroplasty: treatment with arthroscopic acromioplasty.

Pain following total shoulder arthroplasty or humeral hemiarthroplasty is uncommon. Impingement syndrome can be an infrequent source of pain following shoulder arthroplasty. We retrospectively reviewed six patients with refractory impingement syndrome treated with arthroscopic acromioplasty following either total shoulder arthroplasty (four patients) or humeral hemiarthroplasty (two patients). Chronic impingement syndrome requiring acromioplasty affected 3% of all patients who underwent total shoulder arthroplasty or humeral hemiarthroplasty during the study period. A thorough history, physical examination, and radiographic findings made the clinical diagnosis of impingement syndrome. All six patients had positive impingement signs and a positive impingement test with subacromial lidocaine injection. Preoperative radiographs revealed a type II or III acromion and subacromial outlet narrowing in five of six patients. Other sources of shoulder pain including prosthesis loosening, infection, and rotator cuff tear were ruled out preoperatively by physical examination and radiographic findings, and were confirmed by arthroscopic examination. The results of arthroscopic acromioplasty were a reduction in pain from 7.5 preoperatively to 1.6 postoperatively, on a scale from 0 to 10. Five of six patients were completely satisfied with the results of their arthroscopic surgery. Overall, according to the University of California at Los Angeles end-result score, the results were rated as excellent or good in five patients, and unsatisfactory in one patient. Arthroscopic acromioplasty can be a successful technique for the treatment of chronic impingement syndrome following total shoulder arthroplasty or hemiarthroplasty in appropriate patients.

Anterior cruciate ligament injury and reconstruction among university students.

The consequences of athletic injuries extend beyond the musculoskeletal system. Depression, anger, and tension have been observed in athletes with athletic injuries. It was hypothesized that among student athletes, the psychologic impact of injury may be seen as a drop in academic performance. Thirty-eight students who had an anterior cruciate ligament injury and subsequent reconstruction were evaluated retrospectively by academic transcript and questionnaire to measure their academic performance before their injury, in the semester of their injury, and in the semester after their surgery. The patients were compared with randomly selected undergraduate control subjects. To evaluate any effect of the timing of the surgery on academic performance, the patients were separated into two groups, according to the timing of their reconstruction: those who had surgery during the academic semester, and those who elected to wait for a school break. There was a significant drop in grade point average of 0.3 grade points during the semester of injury among all injured students. Compared with those who had surgery during a break, the students who had surgery during the semester received more frequently the grade of failure (6% versus 0%) or incomplete (33% versus 9%). These students also missed more school days (10.5 days versus 1.5 days) and examinations (2.2 examinations versus 0.1 examinations). Only 47% of students who had surgery during the semester were satisfied with their decision for surgical timing, compared with 96% satisfied with the timing during an academic break. Acute anterior cruciate ligament rupture, and surgical reconstruction during an academic semester, have a significant academic effect in university students.

Arthroscopic roofplasty: correction of an extension deficit following conservative treatment of a type III tibial avulsion fracture.

Extension loss following nonoperative treatment of a Type III tibial avulsion fracture does occur. Arthroscopic roofplasty (notchplasty) and scar excision are described to regain complete extension without compromising knee stability.