The natural history of untreated asymptomatic hips in patients who have non-traumatic osteonecrosis.

The aim of this study was to evaluate retrospectively the rate of disease progression in the asymptomatic hip of patients who had non-traumatic osteonecrosis and pain in the other hip. Of seventy-five consecutive patients with non-traumatic osteonecrosis who were initially evaluated between 1978 and 1987, forty-six (61 per cent) initially had pain in only one hip. Radiographs were made for all patients, but routine magnetic resonance images and computed tomography images were not. Twenty-two of the asymptomatic hips had radiographic evidence of involvement, but three of them were excluded because they were treated with elective prophylactic core-drilling; this left nineteen hips with radiographic evidence of involvement in the final study group. The other twenty-four asymptomatic hips had normal findings on the initial radiographs; one of these was treated with elective core-drilling, leaving twenty-three hips with normal radiographs in the final study group. All but one patient, who died at fifty-one months, were followed for at least five years or until symptoms developed in the asymptomatic hip. Of the nineteen untreated asymptomatic hips with initial radiographic evidence of involvement, five were still asymptomatic at the most recent follow-up examination. The other fourteen hips had become painful: nine, within five years after presentation, and five, more than five years after presentation. Pain or radiographic changes developed only rarely in the twenty-three asymptomatic hips with normal findings on the initial radiographs, and only one hip had both pain and radiographic changes within five years after presentation. Nineteen (83 per cent) were still asymptomatic at the most recent follow-up examination. The prolonged pain-free interval for many of the asymptomatic hips with radiographic evidence of involvement contrasts with the over-all rapid progression of disease reported for most hips with non-traumatic osteonecrosis. The present study draws attention to the fact that an adequate period of follow-up is needed for asymptomatic hips that are treated operatively in order to determine whether such intervention alters the natural history of the disease. Our results also showed that few asymptomatic hips with normal findings on initial radiographs are at risk for pain or radiographic abnormalities; when disease does develop, deterioration is slow and operative intervention is rarely indicated.

The evaluation and initial management of arthritis.

This article reviews the appropriate workup of the patient presenting with complaints referable to a joint, including the important information to be obtained during the interview and physical examination, as well as from laboratory and imaging studies. The clinical presentation of osteoarthritis, rheumatoid arthritis, gout, and joint sepsis are discussed, and the treatment approach for each is outlined. The specific indications for surgical intervention in the course of arthritis also are detailed.

Total hip arthroplasty.

Total hip arthroplasty, or surgical replacement of the hip joint with an artificial prosthesis, is a reconstructive procedure that has improved the management of those diseases of the hip joint that have responded poorly to conventional medical therapy. In this review we briefly summarize the evolution of total hip arthroplasty, the design and development of prosthetic hip components, and the current clinical indications for this procedure. The possible complications of total hip arthroplasty, its clinical performance over time, and future directions in hip replacement surgery are also discussed.

Delayed implantation of demineralized bone powder after local irradiation in rats.

Previous studies have shown that osteoinduction is inhibited when demineralized bone powder (DBP) is implanted within 48 hours of local irradiation (i.e., when the acute effects of radiation injury are present). This study sought to determine whether normal osteoinduction can proceed if the implantation of DBP is delayed until 21 days postirradiation. At 21 days, the acute effects of radiation injury are likely to have subsided, but the long-term effects have not yet appeared. Twenty-eight-day-old rats were administered a radiation dose of either 7 or 20 Gy over a localized area of one thigh. The contralateral, nonirradiated thigh served as a control. Demineralized bone powder was subcutaneously implanted 21 days later. Subcutaneous pellets were retrieved at various intervals thereafter (up to Day 45) and were histologically graded for evidence of osteoinduction. No difference in osteoinduction was detected at any time interval in pellets from the 7-Gy-treated sites, compared with controls. Pellets from the 20-Gy-treated sites, however, demonstrated significantly a lower osteoinductive response at each interval. These latter pellets showed small scattered areas of osteoinduction and reduced formation of marrow elements. Thus, although osteoinduction proceeds normally when the implantation of DBP is delayed for 21 days after irradiation with 7 Gy, this is not the case when 20 Gy are administered. Given the absence of gross impairment of tissue vascularity in irradiated sites, it is possible that inhibition of osteoinduction after higher doses of radiation results from permanent damage to mesenchymal precursor cells.

Acute fracture of the femoral neck: assessment of femoral head perfusion with gadopentetate dimeglumine-enhanced MR imaging.

OBJECTIVE: Evaluation of the perfusion and viability of the femoral head after fracture of the femoral neck is important because the outcome of conservative treatment or joint-preserving surgery is adversely affected by the development of capital osteonecrosis. We evaluated the use of MR imaging, before and after IV administration of gadopentetate dimeglumine, for assessing perfusion of the femoral head in 13 patients with acute fracture of the femoral neck. SUBJECTS AND METHODS: Multiecho (1600/30-240 [TR/TE]) MR images were obtained before contrast administration and gradient-echo (315/14, 90 degrees flip angle) MR images were obtained both before and after contrast administration. MR findings were correlated with findings on superselective digital subtraction angiograms of the vessels supplying the femoral head and with clinical-radiographic follow-up for at least 12 months. RESULTS: Digital subtraction angiography showed impaired blood supply to the femoral head in five patients. On contrast-enhanced MR images of these patients, the femoral head did not enhance and was lower in signal intensity than were the enhancing femoral shaft and neck distal to the fracture and the enhancing femoral head on the unaffected side. In the patients with persistent perfusion, contrast-enhanced MR images showed a uniform increase in signal intensity in the femoral shaft and neck as well as the femoral head; the femoral head on the fractured side showed contrast enhancement similar to that on the healthy side. CONCLUSION: These preliminary results indicate that contrast-enhanced MR imaging may be useful for noninvasive evaluation of femoral head perfusion after fracture of the femoral neck. MR findings also may aid the clinician in deciding between joint-preserving therapy and hip arthroplasty.

Imaging of the hip joint. Computed tomography versus magnetic resonance imaging.

The authors reviewed the applications and limitations of computed tomography (CT) and magnetic resonance (MR) imaging in the assessment of the most common hip disorders. Magnetic resonance imaging is the most sensitive technique in detecting osteonecrosis of the femoral head. Magnetic resonance reflects the histologic changes associated with osteonecrosis very well, which may ultimately help to improve staging. Computed tomography can more accurately identify subchondral fractures than MR imaging and thus remains important for staging. In congenital dysplasia of the hip, the position of the nonossified femoral head in children less than six months of age can only be inferred by indirect signs on CT. Magnetic resonance imaging demonstrates the cartilaginous femoral head directly without ionizing radiation. Computed tomography remains the imaging modality of choice for evaluating fractures of the hip joint. In some patients, MR imaging demonstrates the fracture even when it is not apparent on radiography. In neoplasm, CT provides better assessment of calcification, ossification, and periosteal reaction than MR imaging. Magnetic resonance imaging, however, represents the most accurate imaging modality for evaluating intramedullary and soft-tissue extent of the tumor and identifying involvement of neurovascular bundles. Magnetic resonance imaging can also be used to monitor response to chemotherapy. In osteoarthrosis and rheumatoid arthritis of the hip, both CT and MR provide more detailed assessment of the severity of disease than conventional radiography because of their tomographic nature. Magnetic resonance imaging is unique in evaluating cartilage degeneration and loss, and in demonstrating soft-tissue alterations such as inflammatory synovial proliferation.

Age effects on bone induction by demineralized bone powder.

It has been previously shown that osteoinduction by demineralized bone powder (DBP) in the rat decreases as the age of the recipient animal increases. In the present study, the effects of age on osteoinduction by DBP were evaluated in the rat by varying the age of the donor and the recipient animal. Cartilage and bone formation in subcutaneous pouches was assessed using a histologic grading technique in which a composite score was derived from analysis of multiple histologic sections from each specimen. The results confirm the previously reported decrease in osteoinduction in middle-aged adult animals compared with younger ones. However, DBP prepared from middle-aged adult rats was more inductive than that prepared from either prepubertal or young postpubertal animals. The latter result contradicts the widely held belief that demineralized bone matrix from younger animals is more inductive than that from older ones. This finding may help to further elucidate the mechanism of ectopic bone formation and lead to more inductive bone graft substitutes for human use.

Signal variability in magnetic resonance imaging of femoral head osteonecrosis.

The present study was designed to document the pattern and extent of magnetic resonance imaging (MRI) changes in femoral head osteonecrosis and also to correlate MRI findings with technetium bone scans and computed tomograms. Over a three-year period, MRI was performed on 26 patients who had clinical and roentgenographic evidence of femoral head necrosis in one or both hips. MRI abnormalities were present in all 41 hips with osteonecrosis, even when symptoms were absent and roentgenographic findings were nonspecific or not yet apparent. A single possible false-positive MRI was noted in a hip with mild degenerative change. There was considerable variation in the pattern and extent of MRI abnormalities. The most common findings were irregularity of the subchondral cortical outline (82.9%), an inhomogeneous pattern of signal loss (50%), focal increases in signal intensity with T2 weighting (35.5%), and effusion (33.3%). Regions of dense cancellous bone on computed tomograms correlated with bands of low-intensity MRI signal. In the diagnosis of asymptomatic hips, MRI was clearly more sensitive than technetium bone imaging. The role of MRI in defining prognosis and treatment selection remains to be established.

Histologic correlation in magnetic resonance imaging of femoral head osteonecrosis.

The present study was undertaken to determine whether a correlation exists between localized magnetic resonance image (MRI) signal behavior and specific histopathologic features of femoral head osteonecrosis. Contiguous, 5-mm coronal MRI sections were compared with corresponding histologic sections from six surgically excised femoral heads. After identifying specific areas of interest on the images, signal intensity was evaluated, both subjectively and objectively, and T1 and T2 relaxation times were calculated. Mean values for these data were compared among the following histologic categories: normal bone, unrepaired dead bone and marrow, unrepaired dead bone with marrow replaced by amorphous debris, and zones of repair. For each type of tissue, MRI signal intensity on T1- and intermediately T2-weighted images behaved in a distinctive fashion. Active repair tissue could be differentiated from both necrotic bone and normal bone by a tendency for the signal to increase in intensity on intermediately T2-weighted images. These findings suggest that MRI may provide a noninvasive means of quantitatively analyzing the volume and spacial distribution of repair tissue in osteonecrotic femoral heads. In clinical practice, such analysis may lead to improvements in disease staging and treatment planning.

Magnetic resonance imaging of the ischemic femoral head in pigs. Dependency of signal intensities and relaxation times on elapsed time.

The magnetic resonance (MR) signal behavior of freshly excised pig femoral heads undergoing ischemic necrosis in vitro was evaluated. Ten femoral heads removed from skeletally immature pigs were stored at 37 degrees in a sealed, sterile container during the observation period. Imaging was initially performed 40 minutes after excision (base-line) and repeated at six, 12, 24, 48, and 72 hours. Changes in MR signal intensity were measured, and the T1 and T2 relaxation times were calculated for selected epiphyseal and metaphyseal areas. Signal intensities decreased during the first 24 hours and returned to baseline by 72 hours. T1 relaxation time increased most significantly between baseline and 24 hours and then decreased to near baseline level between 48 and 72 hours. T2 changes over time were not statistically significant. The type of localized, distinctive decreases in MR signal intensity occurring in clinical cases of early nontraumatic femoral head osteonecrosis was not observed in pigs. Such changes appear to require the presence of an intact and vigorous repair response within adjacent viable bone. However, the transient decrease in signal intensity and prolongation of T1 relaxation time at 12, 24, and 48 hours after traumatic vascular insult may be indicators of early femoral head ischemia.

Avascular necrosis of the femoral head: high-field-strength MR imaging with histologic correlation.

Magnetic resonance (MR) images, contact radiographs, and histologic sections of six femoral head specimens with avascular necrosis were correlated. A low-signal-intensity band or ring represented the repair tissue interface surrounding a high-signal-intensity necrotic marrow segment. Large segmental areas of low signal intensity were observed on T1-weighted images when the lesion consisted of necrotic bone with amorphous marrow debris and adjacent thickened trabecular bone with mesenchymal repair tissue infiltration. On intermediate-weighted images, however, mesenchymal repair tissue, which was located inferior to the necrotic zone, increased markedly in signal intensity, permitting distinction from low-intensity necrotic bone with amorphous marrow debris. When trabecular thickening with collapse predominated, segmental areas of low signal intensity with both sequences were found. MR signal intensities used in combination with anatomic configuration and location may provide information of potential therapeutic importance regarding tissue composition and stage of disease.

The University of California Biomechanics Laboratory four-bar polycentric knee linkage. A clinical trial in 20 active above-knee amputees.

A four-bar polycentric prosthetic knee linkage developed by the University of California Biomechanics Laboratory (UCBL) was tested clinically in 20 active veteran above-knee amputees. The mean follow-up period was 12.3 months. At final follow-up evaluation, positive subjective responses were reported by 80% of the amputees. More than one-third reported that the device was superior to any that they had used previously. Almost all subjects found that prior levels of daily activity and the ability to perform specific activities were maintained or enhanced. The increase in knee flexion afforded by the mechanism was found to be an advantage. There was no significant change in various fundamental gait parameters. Problems caused by excessive wear of anodized aluminum linkage pins and by air leaks in the pneumatic swing-phase control unit were corrected easily. These preliminary results encourage further clinical application and study of the UCBL four-bar polycentric knee.

Magnetic resonance imaging in osteonecrosis of the femoral head.

Magnetic resonance imaging (MRI) has been used in the assessment of patients with osteonecrosis of the femoral head. Preliminary results indicate that the technique is sensitive to early changes that occur within marrow elements as well as to later changes that involve trabecular bone. Advantages of MRI include its noninvasiveness, the lack of ionizing radiation, a high sensitivity to pathologic changes in bone, and the capability of producing images of equal resolution in all planes.

Magnetic resonance imaging of the musculoskeletal system.

MRI is a complementary technique to CT in the examination of the spine, the hip, and musculoskeletal tumors. In some cases, it provides diagnostic information not available with any other modality, including CT. MRI has the potential to be very useful in the assessment of various marrow-based disorders and may someday obviate the need for contrast-aided studies of ligaments, tendons, and cartilage.

Subjective evaluation of the UCBL polycentric knee linkage by active above knee amputees. A prospective trial.

In this study 20 active male above knee amputees were fitted with prostheses incorporating prototype UCBL four-bar polycentric knee units. The subjective responses of the amputees were evaluated in a prospective fashion. Additional information concerning the short-term durability and mechanical behavior of the device is presented. The average followup was 12.3 months. Sixteen of the 20 subjects felt that they benefited from the device, and seven of these stated that the research prosthesis was superior to all previous devices that they had used. Four subjects stated that they had received little or no benefit from the research limb. Previous levels of function and the ease of performance of specific activities were maintained or enhanced in almost all subjects. Most subjects felt that the ease of walking on inclines was improved, and found the increase in knee flexion afforded by the mechanism to be an advantage. Early in the study, problems were encountered due to air leaks in the pneumatic swing-phase control units and to excessive wear of the aluminum linkage pins. These problems were corrected easily, and the devices were found to function well during the remainder of the study. Given the encouraging results from this preliminary clinical trial, we conclude that further study and clinical application of the UCBL four-bar polycentric knee are indicated.

Evaluation of problems and needs of veteran lower-limb amputees in the San Francisco Bay Area during the period 1977-1980.

From 1977 through 1980, 251 veterans from the San Francisco Bay Area received permanent lower-extremity prostheses at the two local Veterans Administration hospitals. For a survey, 213 of the 251 were contacted and 179 of them (84%) responded to written or telephone questionnaires concerning their prosthetic problems and complaints and their recommendations regarding prosthetic care. Seventy-four percent of the patients were traumatic amputees and 23 percent were dysvascular amputees. Eighty-six percent of the traumatic amputees said they wore their limbs all day, compared with only 51 percent of the dysvascular group. Seventy-one percent of traumatic and 43 percent of dysvascular amputees engaged in some form of recreational activity. There was a high incidence of complaints of pain in the residual limb: 55 percent among the dysvascular group and 44 percent among the traumatic group. Half of the patients had socket problems. Fifty-four of the 178 patients received a physical examination, a prosthetic evaluation, and a gait analysis. Among this group, 59 percent of the below-knee prostheses and 78 percent of the above-knee prostheses had inadequate socket fitting. Improper shaping of socket margins was the most frequently observed deficiency. Moreover, 41 percent of below-knee and 22 percent of above-knee amputees had mechanical skin irritation or skin breakdown in the examined residual limbs. Faulty suspension and alignment in addition to improper socket fit and construction contributed to this problem. Excessive stiffness of SACH foot heel cushions was the most common prosthetic foot problem and contributed to gait abnormalities.

Bilateral total hip and knee replacement in adults with rheumatoid arthritis: an evaluation of function.

Sixteen patients with advanced rheumatoid arthritis who underwent total joint replacements of both hips and both knees were followed for an average of 22.8 months postoperatively. Their functional status before and after surgery was assessed by use of a special rating system for function. Fourteen of the 16 patients demonstrated higher total function scores at follow-up. Improvement was most marked in walking endurance, need for walking aids, and ability to climb stairs. Factors which were believed to predispose to less functional improvement included older age at initial surgery, longer duration of disease, more severe upper extremity involvement, and more frequent medical illnesses. There were 8 patients in whom combined hip and knee flexion in one or both lower extremities did not exceed 190 degrees after surgery. When this deficiency was combined with severe involvement of the upper extremities, difficulty with activities such as climbing stairs and arising from a chair was more common. Therefore, the goal of surgical treatment is to provide combined hip and knee flexion in excess of 190 degrees in these patients. Total joint arthroplasty has increased the likelihood of functional improvement in patients with severe rheumatoid arthritis involving the hips and knees, and encouraged the surgeon to operate earlier in the course of the disease as well as on patients with severely deformed joints.