Metabolic Bone Diseases and Total Hip Arthroplasty: Preventing Complications

Joaquin Moya-Angeler, MD, PhD; Joseph M. Lane, MD; Jose A. Rodriguez, MD

Disclosures

J Am Acad Orthop Surg. 2017;25(11):725-735. 

In This Article

Etiology

Osteoporosis/Osteomalacia

Most osteoporosis-related complications in orthopaedics are associated with fractures and the reaction of the osteoporotic skeleton to joint reconstruction procedures. Although <25% of patients who should be considered for pharmacotherapy to address osteoporosis receive treatment,[14] patients with osteoporosis who are undergoing hip arthroplasty should be questioned about the use of diphosphonates and any other bone catabolic/anabolic agents in the past and their current metabolic bone status.[12] Evidence suggests that diphosphonates aid bony integration of prostheses, improve implant survival, and can help prevent fractures postoperatively.[15] Therefore, it is recommended that diphosphonate use not be stopped perioperatively in patients undergoing joint arthroplasty.[15] For elderly patients with osteoporosis, the use of highly cross-linked polyethylene and cobalt-chromium or ceramic implants, which have been shown to provide a reliable, long-lasting surface with few complications, is recommended.[16] In patients with osteoporosis, special care should be taken during reaming and implant insertion.[16] Noncemented cups have been shown to be a long-lasting and durable option, provided that adequate fixation is accomplished with or without screws. The main problem is the placement of the femoral stem and the risk of periprosthetic fracture. Data from Scandinavian arthroplasty registries have shown a markedly elevated risk (8.8 times) of early periprosthetic fractures in elderly patients with the use of noncemented stems, compared with cemented stems.[17] Although excellent results have been reported with the use of cemented and noncemented femoral implants, we recommend the use of cemented stems in elderly patients with poor bone quality and/or if the surgeon is not familiar with the nuances of a particular noncemented stem.[17] In these scenarios, the use of a cemented stem will reduce the risk of early fracture and subsidence.

Periprosthetic fractures, which occur after 4% of THA procedures, are a major complication of THA in patients with osteoporotic bone.[18] Risk factors include female sex, age, noncemented implants, and revision surgery.[18] Insertional fractures most commonly affect the calcar region.[18] If an insertional fracture is noted intraoperatively, placement of a cable around the calcar is recommended.[18] Fully coated or tapered splined implants are other options that can help achieve stable distal fixation. If the fracture propagates, a revision implant with additional internal fixation may be required. Intraoperative radiography should be used in these patients to ensure appropriate implant position and fracture fixation. Patients with osteoporosis, especially women aged >70 years, also have a high risk of late periprosthetic fracture.[18,19]

Atypical Femoral Fractures

Despite the overall decreased fracture risk with diphosphonate treatment, current data support the association of AFFs with long-term diphosphonate therapy.[7,20] Because of the large number of elderly patients with osteoporosis and groin/thigh pain who undergo hip arthroplasty, surgeons should question patients about past diphosphonates use and look for evidence of AFFs[21] (Figure 2). When areas of cortical thickening are observed on radiographs or dual-energy x-ray absorptiometry scans, additional imaging (ie, MRI, bone scan, CT) is indicated to determine the status of the fracture and rule out contralateral lesions.[20] If hip arthroplasty is indicated in a patient with an AFF, both conditions could be addressed at the same time with the use of long stems and/or open reduction and internal fixation. However, the preference is to first address the fracture and subsequently replace the joint to avoid using long stems as a first approach or predisposing the patient to intraoperative AFF[21] (Figure 3).

Figure 2.

Algorithm for the diagnosis and management of atypical femoral fracture (AFF). 1= positive findings, 2= negative or normal findings, CL = cortical lucency, ME = marrow edema, OA = osteoarthritis, ORIF = open reduction and internal fixation. Asterisk indicates satisfying the criteria of the American Society for Bone and Mineral Research Task Force revised case definition.

Figure 3.

A, AP pelvic radiograph demonstrating a complete right periprosthetic atypical femoral fracture with subsidence of the femoral implant. B, Immediate postoperative AP pelvic radiograph demonstrating a right modular taper stem with two proximal cerclage wires.

Osteonecrosis of the Femoral Head

Osteonecrosis of the femoral head is the final common pathway in a series of derangements that result in decreased blood flow to the femoral head, leading to cellular death, fracture, and collapse of the articular surface.[22] An estimated 20,000 to 30,000 new patients are diagnosed with osteonecrosis every year, accounting for approximately 10% of the 250,000 THA procedures done annually in the United States.[22] Osteonecrosis typically affects relatively young, active people aged 20 to 40 years and regularly follows an unrelenting course resulting in pain and a substantial loss of function.[22] The spontaneous regression of the disease is rare, with most untreated patients progressing to THA.[9] Collapse rates are 67% and 85% in asymptomatic and symptomatic patients, respectively.[9] Currently, patients with osteonecrosis of the femoral head have rates of failure after THA that are similar to those of the general population.[9] However, some risk factors for osteonecrosis, such as renal failure and/or transplant and sickle cell disease (SCD), have been associated with worse outcomes.[23] Although the number of patients with SCD who are undergoing hip arthroplasty is relatively small, these patients have been shown to have a failure rate of ≥20% at 10-year follow up.[23] The hip surgeon should expect to encounter several technical difficulties that have been described in this patient population.[24] The bones of patients with SCD are generally smaller in size than those of the general population; thus, to avoid overpreparation at the expense of bone stock, a range of small-sized implants should be available when needed.[23] In addition, these patients can have deformities in the proximal femur, poor bone quality, and thin sclerotic canals that can make femoral preparation problematic.[23] Hip dislocation can be extremely difficult because of the presence of large osteophytes, protrusio acetabuli, and intra-articular adhesions between the acetabulum and the femoral head.[25] Despite precautions, the incidence of fractures and perforations is higher in these patients than in the overall population.[9] The need for blood transfusion, intense hydration, and oxygenation should be monitored at all times to prevent sickle cell crisis. In addition, patients with SCD are at an increased risk of infection because of their compromised immune status and the poor circulation of blood in bone.[25] A multidisciplinary approach is strongly suggested because most of the complications are preventable.[23]

Paget Disease

Paget disease is a chronic disorder of bone remodeling that typically begins with excessive bone resorption followed by an increase in bone formation ultimately leading to bony deformities, structural weakness, and abnormal joint mechanics.[26] It commonly affects men aged >50 years and has a prevalence in the United States of 1.5% to 3%.[26] The etiology remains unknown, although the disease has been associated with viral, genetic, and environmental causes. The diagnosis is typically made as an incidental finding because patients do not always exhibit symptoms (eg, bone pain/deformity, fracture, arthropathy, skin temperature changes, neurologic complications). Patients with symptomatic Paget disease can be treated with diphosphonates after a thorough metabolic bone assessment. In patients with Paget disease, the incidence of symptomatic OA of the hip is approximately 10%.[11] Although the incidence of hip OA may not be higher in patients with Paget disease than in the overall population, these patients have a specific pattern of joint disease (medial or concentric joint space narrowing) and bony deformity that is influenced by the disease process.[11] A careful preoperative evaluation should be performed in all patients to assess the quality and quantity of the bone as well as the deformities associated with this disease (extremely sclerotic bone, acetabular bone defects, protrusio acetabuli, proximal femoral deformity, coxa vara, and/or large and narrow canals).[8,11] In addition, patients with Paget disease have an increased risk of intraoperative bleeding because of the hypervascularity of the abnormal bone.[11] Although excellent results of THA with noncemented stems have been reported in patients with Paget disease,[8] the surgeon should be aware of and ready to address all possible complications to achieve the best result. In addition, the use of perioperative diphosphonates, such as pamidronate and zoledronic acid,[26] has been advocated to reduce the activity of the disease, avoid rapid postoperative osteolytic bone resorption,[8] and reduce bone hypervascularity to decrease intraoperative blood loss. Other possible intraoperative and/or postoperative complications include the development of heterotopic ossification (occurring in 23% to 52% of patients with Paget disease)[8] and an increased risk of periprosthetic fractures.

Fibrous Dysplasia

Fibrous dysplasia is a benign bone disease characterized by the replacement of normal bone with fibro-osseous tissue.[27] The natural history of fibrous dysplasia is variable, but most cases occur in late childhood and adolescence. It can manifest in a monostotic or polyostotic form, commonly occurs in the proximal femur (manifesting as shepherd crook deformity and chronic fatigue fractures), and may eventually require THA at a relatively young age; OA of the hip develops in 13% of patients with fibrous dysplasia of the femur.[27] The use of second- and third-generation diphosphonates has been advocated as a nonsurgical treatment in select patients. Although THA is a good option for patients with fibrous dysplasia and hip OA, providing long-lasting pain relief and function, these patients have a higher intraoperative complication rate than the overall population does, with better surgical outcomes in patients with monostotic disease than in patients with polyostotic disease.[28] In addition, the long-term fixation of the femoral implant is a concern in these patients.[28]

Osteogenesis Imperfecta

Osteogenesis imperfecta is a heritable genetic disorder caused by a defect in collagen that leads to weak bones, hip deformity, and OA.[10] Osteogenesis imperfecta was initially classified into four types based on genetic and clinical criteria (type I, mild; type II, lethal in the perinatal period; type III, severe with progressive deformity; and type IV, moderate to severe). More recently, three new types of osteogenesis imperfecta were added. Type V is characterized by hypertrophic callus formation after fracture, calcification of the interosseous membrane at the forearm, and hyperdense metaphyseal bands. Type VI is characterized by frequent fractures, vertebral compression, long bone deformity, sclerae of normal color, and absence of dentinogenesis imperfecta. Type VII is characterized by rhizomelic limb shortening and coxa vara.[10]

The prolonged life expectancy of patients with osteogenesis imperfecta has increased the incidence of OA of the hip, which is mainly the result of intra-articular fractures and ligamentous and capsular laxity.[3,29] Certain aspects related to anesthesia and anatomic variation in these patients require special attention.[10] Because of the increased frequency of cervical spine instability in patients with osteogenesis imperfecta, preoperative radiographs are recommended to assist in the diagnosis of the disorder and to prevent complications if general anesthesia is needed.[10] The anatomy of the pelvis, femur, and acetabulum in patients with osteogenesis imperfecta is grossly distorted[29] (Figure 4, A). In patients with osteogenesis imperfecta, the prevalence of protrusio acetabuli is 29%, and the prevalence of coxa vara (ie, shepherd crook deformity) is 21% to 48%.[3] However, the most common long bone deformity is anterior and lateral bowing of the femur (Figure 4, A). In addition, the femur and the intramedullary canal may be abnormally small, and the patient may have excessive anteversion of the femoral neck.[3]

Figure 4.

A, AP pelvic radiograph of a patient with osteogenesis imperfecta demonstrating bilateral severe protrusio acetabuli, hyperplastic callus in both femurs, and severe proximal femoral deformities. B, AP pelvic radiograph of the same patient, 6 months after left total hip arthroplasty and 13 years after right total hip arthroplasty, demonstrating abundant callus in both femora and acetabula. (Reproduced with permission from Ramaswamy R, Kosashvili Y, Cameron H: Bilateral total hip replacement in osteogenesis imperfecta with hyperplastic callus. J Bone Joint Surg Br 2009;91[6]:812–814.)

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