Michael A. Mont

Osteonecrosis of the femoral head. Potential treatment with growth and differentiation factors.

Basic and clinical research have shown the efficacy of various cellular mediators (bone morphogenetic proteins, interleukins, angiogenic growth factors) in healing bone defects. The potential application of these growth and differentiation factors to other musculoskeletal conditions, including osteonecrosis of the femoral head, only recently has been explored. Osteonecrosis is a disease of unknown pathogenesis that usually progresses to hip joint destruction necessitating total hip arthroplasty. The pathology involves ischemic events followed by death of bone and marrow elements. A process of repair then is initiated, but unless the lesion is small (less than 15% of the femoral head involved), this repair process is usually ineffective. The net result is weakening of subchondral bone with subsequent collapse of the articular surface. Because the results of hip arthroplasty in patients with osteonecrosis are relatively poor, much focus has been on modalities aimed at femoral head preservation. The surgical alternatives may include core decompression, osteotomy, nonvascularized, and vascularized bone grafting, which might be enhanced with the use of growth and differentiation factors. At least three of these factors are potential candidates as therapeutic modalities: cytokines (such as interleukins, tumor necrosis factors, and signaling molecules such as fibroblast growth factors, platelet derived growth factors, insulinlike growth factors, and transforming growth factor betas), bone morphogenetic proteins, and angiogenic factors. Despite considerable effort, evaluation of these growth and differentiation factors has been hampered by the lack of an animal model that adequately simulates the pathology of osteonecrosis in humans. Therefore, investigators have attempted to model certain aspects of the disease process. Recently, several investigators have attempted to mimic osteonecrosis in the femoral head of large mammals by combinations of devascularization, freezing, osteotomy of the femoral neck, or creation of a head defect. Results from some of these studies have confirmed the potential for growth and differentiation factors to effect more rapid healing and filling of defects with biomechanically competent and viable bone. The application of this therapy shows promise, and clinical studies on efficacy and safety are ongoing.

Total knee arthroplasty infections associated with dental procedures

Total knee arthroplasties are at risk for hematogenous seeding secondary to procedures that create a transient bacteremia. To define the risk of infection associated with dental surgery, a retrospective review of the records of 3490 patients treated with total knee arthroplasty by the authors between 1982 and 1993 was performed. Sixty-two total knee arthroplasties with late infections (greater than 6 months after their procedure) were identified, and of these, seven infections were associated strongly with a dental procedure temporally and bacteriologically. These seven cases represented 11% of the identified infections or 0.2% of the total knee arthroplasty procedures performed during this period. In addition, among 12 patients referred for infected total knee arthroplasties from outside institutions, two infections were associated with a dental procedure. Five of the nine (56%) patients had systemic risk factors that predisposed them to infection, including diabetes and rheumatoid arthritis. All dental procedures were extensive in nature (average, 115 minutes; range, 75-205 minutes). Eight of the patients received no antibiotic prophylaxis. One patient had only one preoperative dose. Infections associated with dental procedures may be more common than previously suspected. Eight of these patients had no prophylactic antibiotics, and one had inadequate coverage. The authors think that patients with a total knee arthroplasty who have systemic disease that compromises host defense mechanisms against infections and who undergo extensive dental procedures should receive prophylactic antibiotics. A first generation cephalosporin, given 1 hour preoperatively and 8 hours postoperatively would provide the best prophylaxis against the organisms identified in this study.

Upper Extremity Physical Factors Affecting Tennis Serve Velocity

Forty1 tournament-level tennis players with expert serve technique volunteered to have their serve evaluated to determine relationships between anthropometric data, extremity strength, and functional serve velocity. All players underwent a complete physical examination, a video taped serve analysis, a radar measurement of serve velocity, and a series of upper extremity strength measurements. Statistical analysis was performed to determine which factors were related to serve velocity. Statistically significant relationships were found be tween serve velocity and several flexibility measure ments including increased dominant wrist flexion (P < 0.05), increased dominant shoulder flexion (P < 0.05), and increased dominant shoulder internal rota tion at 0° of abduction (P < 0.05). Several strength mea surements were also related to serve velocity including elbow extension torque production (P < 0.01) and the ratios of internal to external rotational torque production for both low- and high-speed measurements (P < 0.01 concentrically and P < 0.05 eccentrically). These findings relate strength and flexibility to serve ve locity, suggesting that it may be possible to increase a tennis players serve velocity through specifically directed muscular strengthening or stretching regimens. However, prospective studies must be undertaken to demonstrate these possibilities.

Partial denervation for persistent neuroma pain around the knee

The authors present the results of denervation procedures treatment for 70 patients with persistent knee pain after total knee replacement, trauma, or osteotomy. In patients with total knee arthroplasty, aseptic loosening, sepsis, ligamentous instability, malalignment, and polyethylene wear had to be systematically ruled out as the source of pain. In patients with nontotal knee arthroplasty, arthrosis, synovitis, ligamentous instability, and meniscal derangement had been excluded as a source of pain. All candidates for the procedure had a successful selective nerve block. Sixty of the 70 (86%) patients were satisfied with the denervation procedure as judged by direct questioning and a reduction in their preoperative pain visual analog score of 5 or more points. The average Knee Society score improved from a preoperative mean of 51 points (range, 40-62 points) to a followup mean of 82 points (range, 15-100 points). Forty-nine of 70 (70%) patients had final Knee Society objective scores greater than 80. There was no difference in patient satisfaction whether the followup period was less than 2 years or more than 2 years. Selective knee denervation is indicated in the management of intractable knee pain after exhaustion of traditional approaches to any structural or infectious etiologies and after successful selective nerve block.

Partial denervation for persistent neuroma pain after total knee arthroplasty

Despite the high percentage of patients who are satisfied completely with the results of total knee arthroplasty, there is a small group who remain disabled because of persistent neuroma pain. Recently, a better understanding of the innervation of the skin and capsule around the human knee joint has provided a theoretical basis for denervation in this group of patients. Fifteen patients were identified who had persistent or worse knee pain for >6 months after total knee arthroplasty. In each patient, component loosening, misalignment, knee instability, and infection had been excluded systematically as a source of pain. Pain was evaluated preoperatively with the Knee Society Functional Score Questionnaire and a visual analog scale. To be selected for surgery, each patient must have had a reduction by 5 points on the visual analogue scale for pain after undergoing selective nerve blocks. Postoperative assessment was done by a team that did not include the surgeon who did the denervation. The technique for selective knee denervation is described in detail. All 15 patients had at least 1 of the nerves to the knee selectively denervated (45 nerves in 15 patients). All patients reported subjective improvement in the immediate postoperative period. This improvement was maintained at a mean followup of 12 months (range, 6–16 months). Selective knee denervation is indicated in the management of intractable knee pain of neuroma origin after total knee arthroplasty.

History of the contralateral knee after primary knee arthroplasty for osteoarthritis

Published reports of series of total knee replacements vary between 20% and 75% in the percentage of patients eventually having bilateral replacements. There are no data in the literature on the predicted course of the contralateral knee for patients presenting for total knee replacement. This study reviewed the history of the contralateral knee in patients with a diagnosis of osteoarthritis presenting for unilateral primary total knee arthroplasty. The current study group comprised 185 patients who had either a minimum 5 year followup (range 5–12.5 years) or who were known to have had a second knee arthroplasty before 5 years. Evaluation included a full clinical and radiographic examination of the contralateral knee at index arthroplasty and at final followup. Of the 185 patients, the contralateral side initially was asymptomatic in 36%, mildly symptomatic in 16%, moderately symptomatic in 28%, and severely symptomatic in 20%. Seventy-nine (43%) knees eventually underwent contralateral arthroplasty. Ninety-three percent of patients who had moderate or severe symptoms and severe radiographic arthritis of the contralateral side at the time of presentation later underwent total knee replacement. However, patients who presented initially with mild symptoms or who had no symptoms had only a 9% incidence of knee arthroplasty.

Radiographic characterization of aseptically loosened cementless total knee replacement.

From January 1980 to December 1992,655 cementless total knee arthroplasties with the PCA total knee system were done at the authors institution. Thirty of these knees have been revised for aseptic loosening of either tibial or femoral components or both. Patients in the failed arthroplasty group were matched directly to a control group with well-functioning, stable and painless cementless total knee prostheses (Knee Society objective score, >90 points). In this study, the authors analyzed any alignment differences between the 2 groups of knees. Special attention was given to the postoperative radiographs to evaluate for potential predictors of success versus failure. Multiple radiographic parameters were measured for each knee and included measures of frontal alignment, sagittal alignment, rotation, percent prosthetic coverage, and cortical thickness (denoted as the cortical-cancellous index). On univariate analysis, no individual radiographic parameter was significantly different in the failure group versus the control group.However, multivariate analysis indicated that certain combinations of abnormal parameters were significantly higher in the failed group than the control group. These parameters included measures of frontal and sagittal plane component alignment. The summated abnormal parameters per patient averaged 3.67 (range, 1–7) for the failure group and 1.80 (range, 0–7) for the control group.

Atraumatic osteonecrosis of the adult elbow.

Osteonecrosis is a disease that leads to joint destruction and often involves large joints, such as the hips, knees, and shoulders. Nontraumatic osteonecrosis of the adult elbow, to the best of the authors knowledge, has not been reported. Nine adult patients with atraumatic osteonecrosis of 11 elbows were identified. The mean age at presentation was 36 years (range, 26-63 years); five patients were women and four were men. Six elbows involved the capitellum, three involved the lateral epicondyles, one involved the trochlea and radial head, and one involved medial and lateral epicondylar disease. All patients were receiving corticosteroid therapy, and no relationship between the duration or the amount of corticosteroid use and the severity of the osteonecrosis was found. Seven patients with radiographic Stage I and Stage II disease responded well to nonoperative treatments consisting of activity modification, analgesics, and a brief period of immobilization. Nonoperative treatment failed in two patients with Stage III disease, and they had core decompressions for pain relief. One patient with late Stage III disease in both elbows underwent bilateral total elbow arthroplasties. In contrast to the pediatric population, osteonecrosis of the adult elbow potentially can lead to end stage arthritis. If the osteonecrosis is diagnosed early, nonoperative treatment may be effective in relieving pain, although the long-term results of these treatments remain unknown.

Management of osteonecrosis in systemic lupus erythematosus.

Osteonecrosis is commonly found in patients with systemic lupus erythematosus. The effects of this disease are magnified because these patients commonly have, in addition to hip involvement, multiple other joints involved with the disease. Early diagnosis is important for medical and surgical management to try to avoid total joint replacements in this young patient population. There are many joint salvaging procedures that have had moderate success in patients with this disease. In the future, pharmacologic agents and growth and differentiation factors may be effective in the early treatment of this disease and may lead to more successful outcomes with surgical options.

Cortical Strut Grafting for Enigmatic Thigh Pain Following Total Hip Arthroplasty

Enigmatic thigh pain remains a difficult problem to treat after total hip arthroplasty. This article reports on the use of strut cortical allografting for the treatment of recalcitrant enigmatic thigh pain following total hip arthroplasty in patients with a well-fixed cemented or cementless femoral component.