Osteonecrosis

PRINCIPLES OF ORTHOPAEDICS

Osteonecrosis

Factors and conditions associated with osteonecrosis C

Mounir Hakimi

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Ahmed Salah Eissa Yousef

C

Hemant Pandit

C C C

Abstract

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Formerly referred to as avascular necrosis, the term osteonecrosis is now preferred. Simply defined, osteonecrosis means ‘dead bone’. The ‘avascular’ state of the necrotic bone is the result of a loss of circulation from numerous potential causes together with multiple risk factors. The resultant state is a sequelae of repair processes leading finally to gross deformation of the bony structural architecture and joint incongruity. Among the commonest sites are the femoral head, talus, lunate, knee and humeral head. In addition to normal radiography, bone scan and MRI have provided early diagnosis of subtle changes in the osteo-histology. Intervention depends upon the phase of disease progression; in the form of a series of preservation and/or salvage procedures.

C C C C C C C C C C C C

Keywords avascular necrosis; femoral head; lunate; osteonecrosis;

Trauma: femoral neck fracture, dislocation Corticosteroids Alcohol Coagulation disorders: thrombophilia, hypofibrinolysis Systemic lupus erythematosus and connective tissue diseases Hyperlipidemias Altered red blood cells: sickle cell anemia, thalassaemia Organ transplants: renal, cardiac, liver Dysbarism Liver dysfunction Gastrointestinal disorders Myeloproliferative disorders: leukemia, Gaucher’s disease Radiation Pregnancy Smoking Hyperuricaemia Chemotherapeutic agents Hypersensitivity reactions Idiopathic

Data from reference Steinberg and Mont (2001).2

review article; shoulder; talus Box 1

None of these theories can fully account for the variety of causes. Most patients with the risk factors just mentioned never develop osteonecrosis, and many patients without identifiable risk factors do acquire the disease. The process is most likely multifactorial.1 See Box 1.

Introduction Formerly referred to as avascular necrosis, the term osteonecrosis is now preferred. Simply defined, osteonecrosis means ‘dead bone’. The ‘avascular’ state of the necrotic bone is the result of a loss of circulation from numerous potential causes. Osteonecrosis describes an end condition that is the result of many possible pathogenic pathways. The list of risk factors for osteonecrosis is long and includes trauma, corticosteroid use, alcohol abuse, smoking, haemoglobinopathies (e.g. sickle cell anemia), coagulation disorders, myeloproliferative disorders (Gaucher’s, leukemia), caisson disease, human immunodeficiency virus infection, and pregnancy. In many cases a cause cannot be identified, and these patients are designated as having idiopathic osteonecrosis.1

Pathogenesis There have been many mechanisms proposed to explain the pathogenesis of osteonecrosis. They can be categorized into six groups: (a) direct cellular toxicity, (b) extraosseous arterial, (c) extraosseous venous, (d) intraosseous extravascular, (e) intraosseous intravascular, and (f) multifactorial (Box 2). Although several different aetiologic factors can lead to vascular impairment in osteonecrosis, the sequence of events that follow the initial insult or insults is similar. The resultant hypoxia rapidly leads to increased cell membrane permeability, which allows fluid and electrolytes to enter the cell, causing it to swell. Intracellular lysosomal enzymes are released, resulting in autodigestion or coagulation necrosis and cell rupture. Vascular injury leads to tissue oedema and haemorrhage. An inflammatory response ensues, marked by the appearance of neutrophils and macrophages.2 In cases of haemoglobinopathies, osteonecrosis is related to the presence of haemoglobin S. The sickling cells cause vessel occlusion leading to local hypoxaemia and cellular death. In homozygotic patients the prevalence is approximately 8% and is even more frequent in double heterozygotes with haemoglobin SC.

Aetiology Several theories on the pathogenesis of osteonecrosis have been proposed. Hypotheses include direct cellular toxicity, coagulopathic states, hyperlipidaemia with fat emboli, vascular interruptions or abnormalities, and elevated bone marrow pressure.

Mounir Hakimi FRCS (Tr&Orth) Senior Hip Fellow, Chapel Allerton Hospital, Leeds, UK. Conflicts of interest: none declared. Ahmed Salah Eissa Yousef MBBCh MSc Trauma & Orthopaedics AinShams University, Egypt; Trauma & Orthopaedic Registrar, Leeds General Infirmary, UK. Conflicts of interest: none declared.

Osteonecrosis of the hip

Hemant Pandit FRCS (Tr&Orth) DPhil (Oxon) Professor of Orthopaedics and Honorary Consultant, University of Leeds, UK. Conflicts of interest: none declared.

Classification The following table (Table 1) describes Ficat and Arlet classification. Stage I is the initiation of the disease without significant

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PRINCIPLES OF ORTHOPAEDICS

Mechanisms explaining pathogenesis of osteonecrosis C

Direct cellular toxicity  Chemotherapeutic agents  Radiation  Thermal injury

C C C

Corticosteroids Alcohol Accumulated cell stress  Extraosseous arterial fractures - Hip dislocation - Post-surgery (iatrogenic) - Congenital arterial abnormalities

Figure 1 Area of osteonecrosis of the femoral head after collapse.

Steinberg et al subsequently devised the University of Pennsylvania System of Classification and Staging. The advantage of this staging system is that it incorporates MRI to detect a preclinical lesion and determines the size of the lesion (Table 2).4

 Extraosseous venous - Venous abnormalities - Venous stasis  Intraosseous extravascular -

Management Osteonecrosis of the femoral head (ONFH) is a disease of the young patient with up to 25% of affected patients being less than 25 years in some institutions. Most patients will ultimately need total hip arthroplasty (THA) and it is estimated that ONFH constitutes about 10% of indications of THA procedures performed in the USA.5 Many modalities have succeeded in slowing the progress of the disease process or even halt it and prevent the collapse of the femoral head and their use could be promising at the early stages of the disease.5 See Figures 2 and 3. Management alternatives for ONFH vary from joint salvaging procedures (including electrical stimulation, proximal femur rotational osteotomy, core decompression sequestrectomy) to replacement with bone cement, non-vascularized cancellous or cortical bone grafting of the lesion, muscle-pedicle bone grafting, and free vascularized fibular grafting. The most commonly used procedures are core decompression, free vascularized fibular grafting and rotational osteotomy. Factors affecting the outcome of these procedures include patient’s age, aetiology and stage of osteonecrosis, and size and location of the osteonecrotic lesion. Preservation of the femoral head with osteonecrosis depends on prevention of collapse of the structurally compromised necrotic bone.6

Haemorrhage Elevated bone marrow pressure Cellular hypertrophy and marrow infiltration Bone marrow oedema Displaced fractures

 Intraosseous intravascular - Coagulation disorders: thrombophilia, hypofibrinolysis C C C C C C

Sickle cell anemia, thalassaemia RBC emboli Lipid emboli Dysbarism Hypersensitivity reactions Multifactorial

Data from reference Steinberg and Mont (2001).2 Box 2

radiological findings. Stage II shows subchondral cysts or sclerosis. Stage III shows broken contour of the femoral head or sequestrum (Figure 1). Stage IV is the end stage with femoral head collapse, flattening and narrowing of the joint space.3

Radiological staging of osteonecrosis of the femoral head Stage

Description

0 I

Preclinical disease with no radiological signs Preradiographic disease with no apparent radiological signs Diffuse porosis, sclerosis or cysts Broken contour of the femoral head, or sequestration present; normal joint space Flattened contour, decreased joint space, head collapse

II III IV

Core decompression: core decompression for treatment of ONFH represents a family of procedures that may include vascularized or non-vascularized bone grafts, bone marrow aspirate (BMA), other biologic agents that promote bone repair, or just the core tract alone.9 In a systematic review of the literature the results of femoral head saving procedures published over the past 10e15 years were evaluated and concluded that core decompression is most effective in the early stages of ONFH and when the lesions are smaller and involve a limited amount of the weight-bearing surface of the femoral head.10 Core decompression is ineffective when the femoral head has already collapsed.10 Ficat described the procedure as introducing a 6- or 8-mm trephine into the lesion from a starting point on the lateral cortex of the greater trochanter. This produced a biopsy of bone for

Data from reference Ficat and Arlet (1980).3

Table 1

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PRINCIPLES OF ORTHOPAEDICS

Steinberg classification for osteonecrosis of the femoral head Stage 0 Stage I

Stage II

Stage III

Stage IV

Stage V

Stage VI

Radiogram, bone scan and MRI are normal Radiogram is normal. Bone scan and/or MRI is normal A e Mild (affected area of femoral head is <15%) B e Moderate (affected area of femoral head is 15e30%) C e Severe (affected area of femoral head is >30%) Cystic and sclerotic changes of femoral head A e Mild (affected area of femoral head is <15%) B e Moderate (affected area of femoral head is 15e30%) C e Severe (affected area of femoral head is >30%) Subchondral collapse without flattening of femoral head (Crescent sign) A e Mild (affected area of femoral head is <15%) B e Moderate (affected area of femoral head is 15e30%) C e Severe (affected area of femoral head is >30) Flattening of femoral head A e Mild (<15% of joint surface and <2 mm collapse) B e Moderate (15e30% of joint surface and 2 e4 mm collapse) C e Severe (>30% of joint surface and >4 mm collapse) Narrowing of the joint surface and acetabular changes A e Mild B e Moderate C e Severe Severe degenerative changes

Figure 2 X-ray of the right hip showing Grade II osteonecrosis of the femoral head.

Figure 3 MRI showing Grade II osteonecrosis of the femoral head (right hip).

Data from reference Steinberg et al (1995).4 MRI, Magnetic resonance imaging.

Table 2

definitive histologic diagnosis. Following this procedure, however, it was noted that patients had improved outcomes with good results obtained in 94% of the patients with Ficat stage I disease. They concluded that the success of core biopsy was due to decompression of the femoral head, permitting venous drainage, and relieving congestion. It was later shown that intraosseous pressure is elevated and the partial pressure of oxygen is lower in patients with ONFH. Core decompression seems to reverse these effects, but the aetiology of ONFH has not been identified. See Figure 4.

Figure 4 Core decompression of femoral head with cannulated drill guided to the osteonecrosed lesion.

hemiarthroplasty requires adequate available bone to support the femoral head resurfacing component. On the other hand, THA provides more predictable pain relief but with higher rates of loosening and osteolysis than THA for other diagnoses. Resurfacing arthroplasty involves both acetabular and femoral resurfacing. Results are influenced by bone stock and extent of necrosis and cyst formation11

Arthroplasty: arthroplasty procedures are saved for later stages (post-collapse). It includes hemiarthroplasty with a unipolar or bipolar prosthesis. It spares acetabular bone. Resurfacing

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PRINCIPLES OF ORTHOPAEDICS

palmar arteries. There are usually one or two foramina dorsally and the same number on the palmar side. In approximately 7% of people there is no dorsal but only a palmar supply. Presumably these people are at more risk for osteonecrosis.8 Lichtman has staged Kienbock’s disease similar to other staging systems for osteonecrosis.

Osteonecrosis of the talus The head of the talus has a large area with limited soft tissue attachment. Blood supply comes via the anterior tibial artery, from branches from dorsalis pedis into the talar neck, from the posterior tibial artery via the deltoid branch and the branch to the tarsal canal, and from the peroneal artery via its branch to the tarsal sinus. Displaced neck fractures with or without subtalar dislocation (Hawkins Type II), have an incidence of avascular necrosis of up to 50%. Type III fractures, with dislocation of the ankle joint as well, have a reported incidence of 75% up to 100%. Again, the incidence appears to be reduced with anatomic reduction and stable fixation. If osteonecrosis is to occur the typical subchondral lucency will be apparent on radiographs at 6e8 weeks and is known as ‘Hawkins’ sign.’ The avascular head may take up to 2 years to re-vascularize.7

Classification and treatment €ck’s disease, plain radiographs appear normal, In stage I Kienbo and bone scintigraphy or magnetic resonance imaging is required for diagnosis. Initial treatment is non-operative. In stage II, sclerosis of the lunate, compression fracture, and/or early collapse of the radial border of the lunate may appear. In stage IIIA, there is more severe lunate collapse. Because the remainder of the carpus is still uninvolved, treatment in stages II and IIIA involves attempts at revascularization of the lunate either directly (with vascularized bone grafting) or indirectly (by

Osteonecrosis of the knee About the knee it is known as SONK which stands for spontaneous osteonecrosis of the knee. This is a disease of the medialfemoral condyle typically that tends to occur in elderly (over the age of 60) females. The pain is usually sudden in onset and early radiographs are often normal.

Staging and treatment of Kienbock’s disease

Diagnosis Diagnosis can be made with an isotope bone scan and typically shows increased activity in that condyle.7 MRI is currently the most useful single study for differentiating osteonecrosis from other conditions. A double density sign is commonly seen, caused by the advancing edge of neovascularization and new bone formation.11

Stage

Description

Treatment

Stage I

No visible changes on X-ray, changes seen on MRI Sclerosis of lunate

Immobilization and NSAIDS

Stage II

Management Conservative: conservative management in the form of narcotics, NSAIDS, protected weight-bearing and physical therapy is the mainstay of treatment as most cases resolve.

Stage IIIA Stage IIIB

Operative: good results have been reported with drilling the affected fragment to reduce intraosseous pressure, prior to collapse. With a small degree of collapse, less than 40% of the surface, the remaining articular surface should protect against early degeneration. With a lesion greater than 40%, an osteotomy may be necessary in order to decrease the pressure across the necrotic compartment. Fresh osteochondral allografts have been used, but although their results are good in traumatic injuries and osteochondritis dissecans, results in spontaneous and steroid-induced osteonecrosis have been poor. In the older person or one with limited life span, a unicompartmental arthroplasty of the knee provides excellent function and early recovery provided the tibiofemora1 angle is not over-corrected.7 Otherwise total knee arthroplasty is advised for larger lesions or bone collapse that precludes the use of unicompartmental knee.11

Stage IV

Proximal row carpectomy, STT fusion, or SC fusion Wrist fusion, proximal row carpectomy, or limited intercarpal fusion

SC, scaphocapitate; STT, scaphotrapeziotrapezoid.

Table 3

Cruess classification for avascular necrosis of the shoulder Stage I Stage II Stage III

Osteonecrosis the lunate Stage IV

Osteonecrosis of the lunate is known as Kienbock’s disease. The cause is not known although repeated compression fractures, transverse fractures, and lunate or perilunate dislocation in individuals with susceptible vascular patterns, have been proposed. The lunate receives its vascular supply from dorsal and

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Lunate collapse, no scaphoid rotation Lunate collapse, fixed scaphoid rotation Degenerated adjacent intercarpal joints

Joint leveling procedure (ulnar negative patients) Radial wedge osteotomy or STT fusion (ulnar neutral patients) Distal radius core decompression Revascularization procedures Same as Stage II above

Stage V

Normal X-ray. Changes on MRI. Core decompression. Sclerosis (wedged, mottled), osteopenia. Core decompression. Crescent sign indicating a subchondral fracture. Resurfacing or hemiarthroplasty. Flattening and collapse. Resurfacing or hemiarthroplasty. Degenerative changes extend to glenoid. Total shoulder arthroplasty.

Table 4

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unloading the lunate). Radial shortening in wrists with negative ulnar variance and capitate shortening or radial-wedge osteotomy in wrists with neutral or positive ulnar variance can be performed alone or with vascularized bone grafting. In stage IIIB, palmar rotation of the scaphoid and proximal migration of the capitate occur, and treatment addresses the carpal collapse. Surgical options include scaphotrapeziotrapezoid or scaphocapitate arthrodesis to correct scaphoid hyperflexion. In stage IV, degenerative changes are present at the midcarpal joint, the radiocarpal joint, or both. Treatment options include proximalrow carpectomy and wrist arthrodesis.12 See Table 3.

REFERENCES 1 Guyton JL. Hip pain in the young adult and hip preservation surgery osteonecrosis of the femoral head. In: Canale ST, ed. Campbell’s operative orthopaedics. 12th ed. Elsevier, 2013. p.358. 2 Steinberg ME, Mont MA. Osteonecrosis. In: Chapman MW, ed. Chapman’s orthopaedic surgery. 3rd ed, vol. 125. Lippincott Williams & Wilkins, 2001; 3265. 3 Ficat RP, Arlet J. Functional investigation of bone under normal conditions. In: Hunderford D, ed. Ischemia and necrosis of bone. Baltimore, MD: Williams and Wilkins, 1980; 29. 4 Steinberg ME, Hayken GD, Steinberg DR. A quantitative system for staging avascular necrosis. J Bone Joint Surg Br 1995; 77: 34. 5 Karam JA, DiIorio TM, Parvizi J. Femoral head osteonecrosisd nonoperative treatment. In: Clohisy JC, ed. Adult hip, the: hip preservation surgery. 1st ed. Lippincott Williams & Wilkins, 2015; 951. 6 Konstantinos N Malizos, Apostolos H Karantanas, Sokratis E Varitimidis, Zoe H Dailiana, Bargiotas Konstantinos, Maris Thomas. Osteonecrosis of the femoral head: etiology, imaging and treatment. Eur J Radiol 2007; 63: 16e28. 7 Mahood JK. Osteonecrosis. Curr Orthop 1990; 4: 40e6. 8 Gelberman RH, Szabo RM. Kienbock’s disease. Orthop Clin NA 1984; 15: 355e67. 9 Petrigliano FA, Lieberman JR. Osteonecrosis of the hip: novel approaches to evaluation and treatment. Clin Orthop Relat Res 2007; 465: 53. 10 Lieberman JR, Engstrom SM, Meneghini RM, et al. Which factors influence preservation of the osteonecrotic femoral head. Clin Orthop Relat Res 2011; 470: 525e34. 11 Vail TP. Total joint arthroplasty/joint salvage. In: Lieberman JR, ed. AAOS comprehesive orthopaedic review, 2009; 997e1001. € ck’s disease: diagnosis 12 Allan CH, Joshi A, Lichtman DM. Kienbo and treatment. J Am Acad Orthop Surg 2001; 9: 128e36.

Osteonecrosis of the shoulder Aetiology: osteonecrosis can arise from the causes outlined above for instance corticosteroid usage or commonly due to trauma. The blood supply to the humeral head is through the ascending branch of the anterior humeral circumflex artery and arcuate artery. The posterior humeral circumflex artery in most of the current literature supports this as providing the main blood supply (65%) to the humeral head. Avascular necrosis in post-traumatic four-part fracturedislocations reaches about 100%. While in displaced four-part fractures it is about 45%. In valgus impacted four-part fractures and three-part fractures, AVN reaches about 11% and 14% respectively. Classification: classification is the Cruess classification (see Table 4). Management: non-operative management includes analgesics, activity modification, physical therapy with restriction of overhead activity and manual labor. Operative management is classified according to staging. For early disease (precollapse; Cruess Stage I and II) use core decompression and arthroscopy (to confirm integrity of cartilage). Humeral head resurfacing is recommended for Stage III disease with focal chondral defects, and sufficient remaining epiphyseal bone stock for fixation. Use hemiarthroplasty for moderate disease (Cruess Stage III and IV) and total shoulder arthroplasty in advanced stage (Cruess V).A

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Acknowledgement All figures are courtesy of Ahmed Yousef.

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