Avascular Necroses in Adults — Chandler’s Disease, Kienböck’s Disease (Lunatomalacia)

Introduction

Avascular necrosis (AVN), also termed osteonecrosis, is the death of bone tissue following interruption of its blood supply. The condition has been recognized since the nineteenth century and remains a major cause of progressive joint destruction and arthroplasty in younger adults. This chapter addresses adult AVN of the femoral head (Chandler’s disease being a historical eponym for the same entity in some literature, though it is also used for idiopathic adult femoral head osteonecrosis as distinguished from secondary forms), AVN of the humeral head, the medial femoral condyle (spontaneous osteonecrosis of the knee, SONK), the talus, the scaphoid (Preiser’s disease), and most importantly the lunate (Kienböck’s disease, lunatomalacia). Each condition shares the underlying pathophysiology of an interruption of the blood supply to bone, but the etiology, clinical presentation, imaging, and treatment differ substantially by anatomical site. The chapter synthesizes content from Apley & Solomon’s, Miller’s Review, Operative Hip Arthroscopy, Netter’s Concise Orthopaedic Anatomy, and the relevant chapters of Rockwood and Green’s and Rothman-Simeone The Spine.

Pathophysiology of Osteonecrosis

The fundamental mechanism in AVN is the disruption of blood supply to a region of bone, followed by ischemic death of osteocytes and marrow elements, attempted revascularization, subchondral fracture, and ultimately collapse of the articular surface. Five general mechanisms can produce the initial vascular insult: (1) mechanical interruption of the vascular supply by trauma, dislocation, or surgical injury; (2) intravascular occlusion by emboli, fat droplets, sickled erythrocytes, or thrombi; (3) extraluminal compression of the vascular supply by raised intramedullary pressure from marrow infiltration (Gaucher’s disease, leukemia), fat-cell hypertrophy (corticosteroid- induced disease, alcoholic disease), or hemorrhage; (4) immunologic and inflammatory injury to vessel walls (systemic lupus erythematosus, vasculitis, antiphospholipid antibody syndrome); and (5) idiopathic or multifactorial events. In the great majority of cases, multiple factors contribute to the final event, and the predisposing factors interact with anatomical features of the affected bone — its vascular dependence on a few critical vessels, the absence of collateral supply, the high demand of weight-bearing — to produce the clinical syndrome. The pathological evolution of osteonecrosis follows a stereotyped sequence regardless of site: first, the immediate ischemic phase with autolysis of osteocytes (apparent within 14- 21 days of the vascular event); next, an inflammatory phase with invasion of vascular granulation tissue and primitive mesenchymal cells from the surrounding viable bone; then a reparative phase in which new woven bone is laid down on the dead trabecular bone scaffold (the so-called “creeping substitution”); and finally either healing or, more commonly in symptomatic cases, subchondral fracture through the weakened bone with secondary collapse of the articular surface. The latter event — articular collapse — marks

the conversion from a potentially reversible early disease to an established, progressive arthritis.

AVN of the Femoral Head

Epidemiology and Etiology Adult AVN of the femoral head is among the most consequential forms of osteonecrosis and one of the principal causes of hip arthroplasty in patients under 50 years of age. The estimated annual incidence in the United States is approximately 20,000-30,000 new cases. The condition is bilateral in 50-80% of cases, often with markedly asynchronous involvement of the two hips. Multiple etiologies are recognized; many cases are multifactorial. Traumatic causes: Femoral neck fracture and posterior hip dislocation are the principal traumatic causes. The risk of AVN following displaced femoral neck fracture is approximately 10-15% after anatomic reduction and prompt fixation, rising to 30% or higher with delayed fixation or inadequate reduction. The risk after posterior hip dislocation is approximately 5-15%, rising substantially if reduction is delayed beyond 6 hours. Non-traumatic causes: Corticosteroid therapy is the commonest non-traumatic cause; the risk rises with cumulative dose, peak dose, and duration of therapy, with the threshold of risk widely quoted as a cumulative prednisone equivalent of approximately 2 g or a daily dose greater than 30 mg of prednisone for more than 30 days. Alcohol abuse is the second most common, with the risk rising with cumulative weekly intake; the proposed mechanism is fat-cell hypertrophy producing raised intramedullary pressure plus alterations in lipid metabolism. Sickle cell disease, in patients of African or Mediterranean descent, produces multifocal AVN through sickling-induced microvascular occlusion. Gaucher’s disease produces AVN through marrow infiltration by glucocerebroside-laden macrophages. Systemic lupus erythematosus and other autoimmune conditions produce AVN through a combination of vasculitis, antiphospholipid antibody-mediated thrombosis, and corticosteroid therapy. Decompression sickness (“caisson disease”) in deep-sea divers and tunnel workers produces dysbaric osteonecrosis, particularly of the femoral and humeral heads. Radiation therapy to the pelvis can produce delayed AVN. Pregnancy- related AVN is rare but well-described, typically in the third trimester or early postpartum and resolving spontaneously in many cases. Idiopathic AVN — historically Chandler’s disease in some references — accounts for cases in which no clear precipitant can be identified despite thorough investigation. Modern molecular studies have implicated thrombophilia (factor V Leiden, prothrombin G20210A, protein C and S deficiencies), hypofibrinolysis, hypercholesterolemia, and other vascular factors in many of these “idiopathic” cases. Clinical Features Presentation is with insidious onset of groin pain, often referred to the anterior thigh or the medial knee, worsened by activity and weight-bearing, with progressive limitation of hip

motion. Early in disease, examination may show only mild restriction of internal rotation. As subchondral collapse and secondary arthritis develop, the typical findings of advanced hip osteoarthritis emerge: marked restriction of internal rotation and abduction, antalgic gait, fixed flexion deformity (positive Thomas test), and shortening of the limb. Imaging and Staging Plain radiographs are normal in early disease and become abnormal only after several months of pathological evolution. The earliest radiographic changes include sclerosis or cyst formation in the superolateral femoral head; the pathognomonic “crescent sign” is a thin radiolucent line of subchondral fracture through the necrotic bone, best seen on frog- lateral views, and represents the transition from a reversible early disease to an established collapse. Subsequent collapse of the articular surface and progression to secondary arthritis complete the radiographic spectrum. MRI is the imaging modality of choice for early diagnosis and staging. The characteristic findings are: focal subchondral marrow edema on T2-weighted images in the early disease; the “double-line” sign on T2-weighted images (a low-signal inner line of necrotic bone with a high-signal outer line of granulation tissue at the reactive interface) is highly specific for AVN; loss of normal enhancement on gadolinium-enhanced sequences corresponding to the avascular area; and the eventual subchondral fracture and articular collapse. Several staging systems are in use: Ficat and Arlet (4 stages): Stage 0, normal imaging, no symptoms; Stage 1, normal radiograph with abnormal MRI and clinical symptoms; Stage 2, sclerotic or cystic changes without subchondral fracture (Ficat 2A) or with subchondral fracture but no collapse (Ficat 2B); Stage 3, articular collapse with crescent sign or step-off of the articular surface; Stage 4, secondary degenerative arthritis with joint-space narrowing. Steinberg (University of Pennsylvania) (7 stages): a more elaborate scheme dividing each Ficat stage into sub-stages based on the extent of head involvement (A = <15%, B = 15-30%, C = >30% of the femoral head). Association Research Circulation Osseous (ARCO) (similar to Ficat, with sub-stages based on extent and location of involvement). The critical clinical question that all staging systems address is whether subchondral fracture has occurred: pre-collapse disease (Ficat I-II, Steinberg I-II) is potentially treatable by joint-preserving surgery, while post-collapse disease (Ficat III-IV, Steinberg III-IV) is best managed by arthroplasty. Treatment The treatment of femoral head AVN aims to preserve the native hip in pre-collapse disease and to provide durable joint replacement in post-collapse disease.

Conservative management with restricted weight-bearing, analgesia, and observation has historically been used but has poor outcomes in symptomatic disease, with progression to collapse in the majority of cases. Pharmacologic therapy with bisphosphonates (alendronate, zoledronate) reduces bone turnover and has been advocated in early disease, with some evidence for delay of progression. Statins, anticoagulants, and prostacyclin analogs (iloprost) have been studied with variable results. Core decompression is the standard joint-preserving procedure for pre-collapse disease (Ficat I-II). The procedure involves drilling a single large-diameter (8-10 mm) channel or multiple small-diameter (3-5 mm) channels from the lateral cortex of the femur into the necrotic region of the femoral head. The mechanism is multifactorial: decompression of raised intramedullary pressure; promotion of revascularization through the drilled tract; and stimulation of bone formation through the trauma of drilling. Reported success rates are 60-80% in pre-collapse disease, dropping precipitously in post-collapse disease. Core decompression is often combined with adjunctive therapies: autogenous bone marrow concentrate, bone morphogenetic protein, demineralized bone matrix, or vascularized fibular grafting. Vascularized fibular grafting involves harvesting the contralateral fibula with its peroneal artery and vein, transferring it to the femoral head through a core decompression tract, and microvascular anastomosis to recipient vessels in the thigh. The procedure has the dual advantages of providing structural support to the subchondral bone and bringing in fresh blood supply. Reported success rates in pre-collapse disease are 70-90%, with substantially better results than core decompression alone in some series. Disadvantages include the donor-site morbidity (peroneal nerve injury, dorsiflexor weakness, ankle pain) and the technical demands of microvascular surgery. Osteotomy (transtrochanteric rotational osteotomy, Sugioka osteotomy; or valgus-flexion osteotomy) redirects the necrotic segment out of the principal weight-bearing region of the acetabulum. The procedures have been more popular in Asia than in Western countries, with reported success rates of 50-80% in selected pre-collapse and early post-collapse cases. Total hip arthroplasty (THA) is the treatment of choice for post-collapse disease. The technical considerations are similar to those of THA for primary osteoarthritis, but with some additional considerations: the typical younger patient demands a more durable bearing (ceramic-on-ceramic or ceramic-on-highly-cross-linked-polyethylene); the underlying cause may affect bone quality (long-term corticosteroid therapy produces osteopenia); and the contralateral hip may already be involved or at high risk. Modern THA in this population produces excellent functional outcomes with 10-15 year survivorship of >95% in many series. Bipolar hemiarthroplasty has been used in selected younger patients but has largely been supplanted by THA.

Spontaneous Osteonecrosis of the Knee (SONK)

Spontaneous osteonecrosis of the knee, also known as Ahlbäck’s disease, is a focal osteonecrotic lesion of the subchondral bone of the medial femoral condyle (less commonly the medial tibial plateau or lateral femoral condyle), occurring predominantly in older women (>60 years) without antecedent trauma or significant risk factors for systemic AVN. The condition is now understood as a subchondral insufficiency fracture in osteoporotic bone with secondary osteonecrosis of the overlying bone, rather than a primary vascular event — the term “spontaneous osteonecrosis” is therefore something of a misnomer, but it has been preserved by tradition. Presentation is with sudden onset of medial knee pain, often nocturnal, without identifiable trauma. Plain radiographs early in disease are normal; later, a subchondral lucency in the medial femoral condyle appears, with surrounding sclerosis and eventual collapse. MRI is diagnostic in the acute phase, demonstrating the characteristic subchondral fracture line with surrounding marrow edema and a focal area of low signal corresponding to the necrotic segment. Treatment is initially conservative (restricted weight-bearing, NSAIDs, bisphosphonates), with high tibial osteotomy or unicompartmental knee arthroplasty considered for persistent symptoms in the appropriate candidate, and total knee arthroplasty for tricompartmental progression or for older patients.

AVN of the Humeral Head

AVN of the humeral head is the second most common site of non-traumatic osteonecrosis after the femoral head, and is associated with the same systemic risk factors (corticosteroid therapy, alcohol abuse, sickle cell disease, lupus, etc.). It also occurs as a complication of complex proximal humerus fractures (particularly three- and four-part fractures and head- splitting fractures, with rates of 20-50% in displaced four-part fractures). The vascular supply to the humeral head is predominantly through the arcuate artery, the terminal ascending branch of the anterior humeral circumflex artery, which enters the head through the lateral aspect of the bicipital groove; disruption of this vessel by fracture displacement produces the high AVN rates of complex proximal humeral fractures. Clinical presentation is with progressive shoulder pain, often nocturnal, and progressive loss of motion. Staging follows the Cruess classification, analogous to the Ficat system: Stage 1, normal radiograph with abnormal MRI; Stage 2, sclerotic changes without subchondral fracture; Stage 3, crescent sign with subchondral fracture; Stage 4, articular collapse; Stage 5, secondary arthritis. Treatment in early stages includes core decompression with or without bone graft; in advanced disease, hemiarthroplasty or total shoulder arthroplasty (anatomic or reverse, depending on rotator cuff status) is the standard.

AVN of the Talus

AVN of the talus is most commonly a complication of talar neck fractures, with rates rising with the displacement of the fracture (Hawkins type I, 0-10%; type II, 20-50%; type III, 80- 100%; type IV, near 100%). The Hawkins sign — a subchondral radiolucency seen in the talar dome on the AP view 6-8 weeks after injury, indicating intact vascular supply and viability of the talar dome — is the classical positive prognostic sign. Non-traumatic AVN of the talus is uncommon but is associated with the systemic risk factors of other AVN sites.

Treatment of early symptomatic AVN of the talus may include conservative management or core decompression; advanced disease with collapse is treated by ankle arthrodesis or, in selected cases, total ankle arthroplasty.

Kienböck’s Disease (Lunatomalacia)

Definition and Epidemiology Kienböck’s disease, also called lunatomalacia, is an avascular necrosis of the carpal lunate. First described by Robert Kienböck in 1910, the condition predominantly affects men aged 20-40 years engaged in manual labor, and is one of the principal causes of progressive wrist disability in this population. Bilateral disease is uncommon (5-10%) but does occur and is often associated with systemic risk factors.

Pathogenesis The etiology of Kienböck’s disease remains incompletely understood. Several theories have been proposed: (1) repeated micro-trauma producing cumulative damage to the intraosseous vascular supply of the lunate; (2) a single traumatic event with disruption of the lunate’s blood supply; (3) anatomical predisposition based on the variability of the lunate’s vascular supply (the lunate may have one, two, or three nutrient vessels entering through palmar and dorsal foramina); (4) the influence of ulnar variance — patients with ulnar-negative variance (a relatively short ulna compared with the radius) demonstrate a statistically higher prevalence of Kienböck’s disease, presumably because more axial load is transmitted through the lunate as opposed to being shared with the triangular fibrocartilage complex. The combination of vascular vulnerability and increased mechanical loading appears to be the most plausible unifying explanation.

Lichtman Classification The Lichtman classification, the standard staging system, recognizes four stages with substages: Stage I: Normal radiograph; abnormal MRI (decreased signal on T1-weighted images) representing early ischemic disease. Treatment is conservative. Stage II: Sclerosis of the lunate on plain radiographs, with preserved lunate shape and architecture. Stage IIIA: Collapse of the lunate with maintained carpal alignment (no proximal migration of the capitate, normal carpal height). Stage IIIB: Collapse of the lunate with carpal collapse — proximal migration of the capitate, decreased carpal height, scaphoid flexion (with positive lateral scapholunate angle), and increased ulnar translation of the carpus. Stage IIIC: Coronal fracture through the lunate. Stage IV: Pancarpal arthritis affecting the radiocarpal and midcarpal joints.

Clinical Features Presentation is with progressive wrist pain, particularly with use, accompanied by stiffness, decreased grip strength, and tenderness over the dorsal aspect of the lunate. Range of motion is reduced. Symptoms commonly persist for months before diagnosis. Imaging Plain radiographs (PA and lateral views) demonstrate the characteristic stages: stage I, normal; stage II, sclerosis; stage IIIA, collapse without carpal malalignment; stage IIIB, collapse with carpal malalignment; stage IIIC, coronal lunate fracture; stage IV, pancarpal arthritis. Ulnar variance should be assessed on the PA view with the wrist in neutral rotation and the elbow flexed to 90°. MRI is sensitive for early disease and demonstrates decreased signal of the lunate on T1-weighted images with variable T2 signal; gadolinium enhancement is reduced in necrotic areas. CT is useful for detailed assessment of lunate fragmentation and carpal alignment. Treatment Treatment of Kienböck’s disease is stage-dependent and remains an area of ongoing debate. Stage I: Conservative management with immobilization and observation. Some authors recommend a trial of cast immobilization for 2-3 months in this stage with reassessment. Stage II and IIIA (ulnar-negative variance): Joint-leveling procedures aim to redistribute load away from the lunate by equalizing the relative length of the radius and ulna. Two main options exist: radial shortening osteotomy (preferred in most centers, particularly for ulnar-negative variance) involves a transverse osteotomy of the distal radius with removal of a 2-4 mm wedge and rigid plate fixation; ulnar lengthening (less commonly used) achieves the same effect by lengthening the ulna with a step-cut osteotomy and bone graft. Both procedures reduce load transmission through the lunate and produce reliable pain relief and functional improvement. Stage II and IIIA (ulnar-positive or neutral variance): Joint-leveling osteotomies are contraindicated in ulnar-positive variance and produce less reliable outcomes in ulnar- neutral variance. Alternative options include capitate shortening osteotomy (offloads the lunate from above), capitate-hamate fusion (offloads the lunate by transferring load through the midcarpal joint), or vascularized bone grafting. Vascularized bone grafting has been increasingly used in stages II and IIIA. The pedicled bone graft from the dorsal aspect of the distal radius (4+5 ECA pedicled flap, based on the dorsal extensor compartmental arteries) is the standard technique, transferring vascularized cancellous bone into the lunate to promote revascularization. Free vascularized bone grafts from the medial femoral condyle have also been described. Stage IIIB: The presence of carpal collapse with malalignment makes joint-leveling osteotomy less effective, and more aggressive procedures are required. Options include proximal row carpectomy (PRC, removal of the scaphoid, lunate, and triquetrum, with

articulation of the capitate against the distal radius), partial wrist arthrodesis (scaphocapitate or scaphotrapeziotrapezoid fusion, preserving the radiolunate joint when it is intact), or in advanced disease total wrist arthrodesis. Stage IIIC: Coronal lunate fracture demands proximal row carpectomy or partial wrist arthrodesis; joint-leveling alone will not address the disrupted lunate architecture. Stage IV: Established pancarpal arthritis requires total wrist arthrodesis or, in selected patients with low functional demands, total wrist arthroplasty. The choice between PRC and partial wrist arthrodesis in stage IIIB and IIIC disease depends on the integrity of the capitate-lunate articulation: if the proximal pole of the capitate is intact and shows no arthritic changes, PRC provides good pain relief with reasonable preservation of wrist motion; if the capitate is involved, partial arthrodesis is preferred. Outcomes The long-term outcomes of Kienböck’s disease are highly variable. Many patients with early-stage disease achieve good pain relief and functional improvement with joint-leveling osteotomy and remain functional for decades; others progress despite treatment and ultimately require salvage procedures. The natural history of untreated Kienböck’s disease is one of progression in the majority of cases, though spontaneous arrest of disease has been described.

Other Sites of Adult AVN

Preiser’s Disease (AVN of the Scaphoid) Idiopathic AVN of the scaphoid — Preiser’s disease — is rare and predominantly affects women aged 30-50 years. The proximal pole of the scaphoid is the typical site of involvement. Risk factors include corticosteroid therapy, alcohol abuse, and a history of scaphoid fracture or repeated micro-trauma. Treatment options include vascularized bone grafting in early disease, scaphoidectomy with four-corner fusion in established arthritis, and proximal row carpectomy. Mueller-Weiss Disease (AVN of the Navicular) Mueller-Weiss disease is an idiopathic AVN of the tarsal navicular in adults, distinguished from the childhood Köhler’s disease by its different clinical course and population. The condition presents with midfoot pain in middle-aged women and is treated conservatively in early disease and with selective tarsal arthrodesis in advanced disease. Freiberg’s Disease (AVN of the Second Metatarsal Head) Freiberg’s disease is an osteonecrosis of the second (occasionally third) metatarsal head, typically presenting in adolescent girls and young women with forefoot pain and metatarsalgia. Treatment is initially conservative; surgical options for advanced disease include dorsiflexion osteotomy of the metatarsal head and excisional arthroplasty.

Summary and Take-Home Points

Adult avascular necrosis is a heterogeneous group of conditions unified by the underlying mechanism of vascular insult, bone death, and progressive joint destruction. The femoral head is the principal site, with corticosteroid therapy, alcohol abuse, sickle cell disease, and a constellation of other systemic factors as the main etiologies; the Ficat-Arlet and Steinberg staging systems guide treatment decisions, with core decompression (often combined with bone marrow concentrate or vascularized bone grafting) for pre-collapse disease and total hip arthroplasty for post-collapse disease. Spontaneous osteonecrosis of the knee (Ahlbäck’s), now understood as a subchondral insufficiency fracture, predominantly affects older women and is treated conservatively or by knee arthroplasty as the disease progresses. AVN of the humeral head, talus, lunate, and scaphoid share similar pathological principles but have site-specific clinical features and treatments. Kienböck’s disease, the AVN of the carpal lunate, demonstrates a particularly distinctive natural history and management, with joint-leveling procedures (radial shortening osteotomy) for ulnar-negative variance in early stages, vascularized bone grafting in selected cases, and proximal row carpectomy or partial arthrodesis for advanced disease. Across all of these conditions, the principles of early diagnosis by MRI, identification and correction of modifiable risk factors, and stage-appropriate treatment that combines joint- preserving and joint-replacing options determine successful outcomes.