Anyone suffering from osteonecrosis of the knee if so how are you treated for it?

Osteonecrosis literally means 鈥渄ead bone.鈥?It most often refers to a form of arthritis in which one of the bones of a joint is affected by osteonecrosis, leading to arthritis in the joint. Osteonecrosis is known by many other names, such as avascular necrosis or ischemic necrosis. Osteonecrosis occurs because of a decrease in blood supply to specific parts of bones. This decreased circulation causes cells in the bone and bone marrow to begin to die. Eventually the dead section of bone weakens and collapses.

An arthritic or damaged joint is removed and replaced with an artificial joint called a prosthesis.

Medical therapy: Several nonoperative and operative treatment options exist for osteonecrosis of the knee. SPONK and secondary osteonecrosis can be treated nonoperatively when the patient is asymptomatic. However, once the patient is symptomatic, treatment options for the 2 entities differ.

Nonoperative treatment has shown to produce good results in patients with SPONK. This encompasses a conservative regimen of protected weightbearing with crutches, analgesics, nonsteroidal anti-inflammatory medications, and physical therapy focusing on strengthening the quadriceps and hamstrings. Lotke et al reported on 87 knees with SPONK. Thirty-six of these knees were treated nonoperatively, with only 1 progressing to arthroplasty. The 35 remaining knees did well.

Outcomes of this nonoperative regimen in secondary osteonecrosis are relatively poor. One study of 51 knees with secondary osteonecrosis treated nonoperatively reported that eventually, 31 knees required arthroplasty. Nonoperative treatment has shown poor results in secondary osteonecrosis. Therefore, operative therapy usually is used once the patient is symptomatic.

Pharmacotherapy has been attempted with mixed results. Medications are aimed at attacking the pathophysiology of the disease. Examples include nifedipine and lipid-lowering agents, such as Lopid.

Surgical therapy:


Arthroscopy

Arthroscopic debridement for treatment of osteonecrosis of the knee has had mixed results. Arthroscopy may not alter the natural course of the disease. Patients with SPONK may have degenerative tears of the menisci. Debridement of these tears does not improve osteonecrosis of the bone. Partial meniscectomy actually has been hypothesized to possibly cause further degeneration of the knee joint. Arthroscopy is controversial, with questions arising about the possibility of increased interosseous pressure.

Osteochondral grafts

Reports regarding results with osteochondral allografts have been discouraging for both SPONK and secondary osteonecrosis. Bayne et al used fresh allografts in 6 knees with SPONK, resulting in only 1 good result. The authors suspect that these poor results were due to the poor compliance of elderly patients, resulting in fragmentation of the allograft. The 3 knees with steroid-induced secondary osteonecrosis also failed the grafting procedure. This may be due to continued use of corticosteroids, which may lead to poor vascularization of the graft and subsequent subsidence.

Some surgeons have focused on using osteochondral autografts. This procedure, commonly referred to as an OATS (osteochondral autologous transfer system), was first introduced by Matsusue in 1993. Using this procedure, Hangody et al reported a 2-5 year follow-up with good or excellent results in up to 90% of cases. Use of other grafting methods may improve results, but further studies are required.

High tibial osteotomy

High tibial osteotomy (HTO) has been used in patients with SPONK with encouraging results. Aglietti et al described 31 patients treated with high tibial osteotomy, with 21 of these knees having ancillary bone grafting. Of the 31 knees, 87% had excellent to good results at a mean follow-up of 6.2 years, and only 2 knees progressed to arthroplasty. Use of high tibial osteotomy in secondary osteonecrosis is limited because most of these patients have bicondylar femoral involvement and also may have tibial involvement.

Core decompression

The principal behind core decompression is reduction of interosseous pressure, thereby restoring adequate circulation. This procedure has been used with some success in the earlier stages of osteonecrosis. Core decompression is a relatively lesser procedure than total knee arthroplasty, and it has been shown to delay the need for joint replacement.

Core decompression has been used with some success in SPONK. Forst et al achieved successful outcomes with core decompression of the femoral condyle in precollapsed lesions in their study of 16 knees. Results have not been as encouraging with SPONK as in secondary osteonecrosis. Therefore, it should be reserved for refractory cases.

Mont et al reported on 79 knees that were treated for secondary osteonecrosis. Forty-seven knees were treated with core decompression, and 32 were treated nonoperatively. For core decompression, clinical success was achieved in 73% (34 of 47) of knees (good to excellent Knee Society Scores) at a mean follow-up of 11 years (range of 4-16 y). Radiographically, seventeen of the 47 (36%) knees progressed to Ficat and Arlet stage III or IV, as opposed to 24 of 32 knees (75%) treated nonoperatively.

Unicondylar (unicompartmental) knee arthroplasty

Unicondylar arthroplasty has been used with success in SPONK, as the disease usually is confined to 1 condyle (see Image 3). This procedure is not, however, recommended for secondary osteonecrosis, as the disease can affect both condyles. Marmor reported an 89% success rate in a study of 34 knees with medial femoral condyle osteonecrosis treated with unicondylar replacement.

Total knee arthroplasty

Knee arthroplasty is indicated in the late stages of the disease, when patients have severe pain that does not respond to other treatments (see Image 4). Total knee arthroplasty is an appropriate intervention for late-stage secondary osteonecrosis with degenerative changes, for patients with severe pain, or for those with functional disability. It has had varying success with SPONK. Bergman and Rand reported that 87% of 38 knees treated with total knee arthroplasties had excellent or good results. Of those knees, 27 had SPONK, and 9 had secondary osteonecrosis. These results were inferior to those of total knee replacements performed for other diagnoses.

Ritter et al compared 32 knees with SPONK to 63 osteoarthritic knees. The success rate was 82% in SPONK knees, and no statistical significance of success rates exists between the 2 groups. For secondary osteonecrosis, Mont et al reported on 31 knees treated with total knee arthroplasty; all of these patients had a history of corticosteroid use. After 8.2 years mean follow-up, results were 55% excellent to good.

Spontaneous Osteonecrosis of the Knee

Diane Wilkinson, M.D.
James Stevan Nagel, M.D.
October 7, 1986
CASE PRESENTATION:
A 79 year-old woman noted the relatively acute onset of left knee pain without antecedent trauma. Physical examination revealed tenderness, but no limitation of motion. Her list of medications did not include steroids.

Findings:
Plain radiographs obtained in August 1986 showed changes of osteoarthritis in the medial compartment, and a subchondral lucency (shown by arrow) and surrounding sclerosis, findings suggestive of osteonecrosis. Bone scintigraphy (left medial | anterior | left lateral) performed one month later showed intense uptake of Tc-99m MDP in the medial condyle of the left femur (shown by arrow). These findings are diagnostic of spontaneous osteonecrosis of the knee. She was treated conservatively, as she refused the unicondylar prosthesis recommended by her orthopedic surgeon.

DISCUSSION:
The clinical symptoms and signs of spontaneous osteonecrosis of the knee vary in severity and may mimic other conditions such as meniscal tears and osteoarthritis. In most reports to date, the diagnosis was made in patients with clinical symptoms and the typical radiographic findings which include subchondral lucency in the medial femoral condyle, flattening of the medial femoral condyle, and a narrow zone of increased radiodensity adjacent to the depressed osseous surface. In these patients bone scintigraphy is positive but its role is largely confirmatory. It plays an important role in patients with symptoms and normal or non-diagnostic plain radiographs. In one study of twelve such patients, bone scintigrams showed intense uptake in the affected condyle. In two of the twelve, Craig-needle biopsy was carried out and showed spicules of dead bone without new bone formation. The patients were treatment with protected weight bearing. They became asymptomatic and the bone scans returned to normal in a few months. None of the twelve ever showed characteristic plain radiographic findings. No long term follow-up was available (1).
Bone scintigraphy in this setting may not be specific. A torn meniscus by itself was thought not to cause a positive scan (2,4). A more recent report suggests that SPECT imaging is positive in chronic meniscal tears (5). Older reports (3,4) using rectilinear scanners, subdivided the knee into quadrants and suggested the diagnosis of osteonecrosis as opposed to medial osteoarthritis if the ratio of the medial proximal to the medial distal quadrant was high. Modern planar imaging more easily demonstrates the focality of the lesion. SPECT imaging was more highly sensitive (.91) in identifying osteoarthritis in the patellofemoral compartment. The specificity was 1.00. This report did not deal with SPECT imaging in spontaneous osteonecrosis of the knee, but raises the possibility that it may play a role in demonstrating the focality of the lesion and perhaps increasing specificity. If the lesion can be identified early and therapy instituted, the prognosis should improve, as two studies show that prognosis can be based on the size of the lesion.

In summary, bone scintigraphy plays an important role in the management of patients with suspected osteonecrosis of the knee and non-diagnostic plain radiographs. Early identification of spontaneous osteonecrosis should improve prognosis of this entity.


REFERENCES:
Aglietti P, Insall JN, Buzzi R, Deschamps G. Idiopathic osteonecrosis of the knee. J Bone Joint Surg (Br) 1983; 65:588-597.

Lotke PA, Ecker ML, Alavi A. Painful knees in older patients. Radionuclide diagnosis of possible osteonecrosis with spontaneous resolution. J Bone Joint Surg (Am) 1977; 59:617-621.

Muheim G, Bohne WH. Prognosis in spontaneous osteonecrosis of the knee. Investigation by radiography. J Bone Joint Surg (Br) 1970; 52:605-612.

Rozing PM, Insall J, Bohne WH. Spontaneous osteonecrosis of the knee. J Bone Joint Surg (Am) 1980; 62:2-7.

Collier D, et al. Chronic knee pain assessed by SPECT: comparison with other modalities. Radiology 1985; 157:795-802.

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J. Anthony Parker, MD PhD, jap@nucmed.bih.harvard.edu