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Long-Term Survivorship of Cemented Bipolar Hemiarthroplasty for Fracture of the Femoral Neck

Haidukewych, George J., MD; Israel, T. Andrew, MD; Berry, Daniel J., MD

Clinical Orthopaedics and Related Research®: October 2002 - Volume 403 - Issue - p 118-126
SECTION II ORIGINAL ARTICLES: Spine
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Cemented bipolar hemiarthroplasty commonly is used to treat displaced fractures of the femoral neck in elderly patients. The purpose of the current study was to review the results and survivorship of 212 bipolar hemiarthroplasties done in 205 patients for acute femoral neck fracture between 1976 and 1985. The mean age of the patients at the time of surgery was 79 years (range, 61–100 years). The mean followup for the patients who were alive was 11.7 years (range, 5.3–16.8 years) and 5.8 years (range, 51 days–19.4 years) for the entire group. Ten hips (4.7%) were revised or removed: five for aseptic femoral component loosening, one for acetabular erosion, one for chronic dislocation, and three for infection. In living patients with surviving implants, 96.2% had no or slight pain. Ten-year survivorship free of reoperation for any reason was 93.6%, free of revision surgery for aseptic femoral loosening or acetabular cartilage wear was 95.9%, free of revision surgery for aseptic femoral loosening was 96.5%, and free of revision surgery for acetabular cartilage wear was 99.4%. Cemented bipolar hemiarthroplasty for acute femoral neck fracture is associated with excellent component survivorship in elderly patients. The rate of complications was low, and the arthroplasty provided satisfactory pain relief for the lifetime of the majority of elderly patients.

From the Department of Orthopedics, Mayo Clinic, Rochester, MN.

Reprint requests to George J. Haidukewych, MD; Mayo Clinic, 200 First Street, SW, Rochester, MN 55905.

Received: June 13, 2001.

Revised: October 25, 2001; December 6, 2001.

Accepted: December 20, 2001.

The treatment of displaced femoral neck fractures in elderly patients is controversial. 1,34,52 As age and life expectancy increase, so does the prevalence of intracapsular hip fractures. It is estimated that the cost of treatment of patients with proximal femoral fractures exceeds eight billion dollars annually in the United States. 34 There is a paucity of long-term data in the literature to guide the clinician treating these common injuries. Some authors have advocated reduction and fixation of these injuries. 1,50 However, the literature shows unacceptably high rates of fracture nonunion and osteonecrosis of the femoral head. 1,34,35,50 Additionally, the challenges of fixation in osteoporotic bone and patients’ difficulty complying with postoperative weightbearing restrictions are considerable. These patients often are debilitated by significant medical comorbidities and may be better served by one operation that restores function quickly. To address these concerns some authors advocate primary prosthetic replacement. 1–5,12,13,15,16,18–22,27–31,33–41,44,45,47,48,50–56 The choice of prosthesis type and fixation for these injuries also is controversial. Unipolar, bipolar, and total hip arthroplasty have been used with various fixation methods. 1–5,12,13,15,16,18–22,27–31,33–41,44,45,47,48,50–56 To learn more about the long-term results of cemented bipolar hemiarthroplasty in this patient population, the current authors reviewed the records of 224 consecutive cemented bipolar hemiarthroplasties done between 1976 and 1985.

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MATERIALS AND METHODS

Between 1976 and 1985, 224 consecutive cemented bipolar hemiarthroplasties were done at the authors’ institution for displaced femoral neck fractures in 217 patients who were 60 years or older. Patients with pathologic fractures, nonunions, or failed open reduction and internal fixation were excluded. This left 205 patients with 212 hip fractures for review. The indication for hemiarthroplasty was a displaced intracapsular fracture of the femoral neck related to a fall in all patients. Clinical and radiographic information on all patients was collected prospectively as a routine part of monitoring of all arthroplasties at the authors’ institution. The patients’ charts and radiographs were reviewed retrospectively. All patients were contacted at 1, 2, 5, 10, 15, and 20 years from surgery for clinical evaluation in person or by questionnaire and asked to have radiographs of their hips obtained at the same intervals. The questionnaire evaluated pain and functional status as part of the Total Joint Registry. Data were collected by review of hospital charts, operative notes, physician office records, nursing home records, and telephone messages with the patient, family, or home attendant. The study was approved by the institutional review board and written informed consent was obtained.

There were 109 fractures in left hips (51.4%) and 103 fractures in right hips (48.6%). One hundred sixty-nine fractures occurred in women (79.7%) and 43 occurred in men (20.3%), with a ratio of 3.9:1. Seven patients had bilateral hemiarthroplasties (3.2%). The mean age at the time of surgery was 78.8 years (range, 60.7–99.6 years). An anterolateral operative approach was used in 167 hips and the posterior approach was used in 45 hips. The cemented femoral component designs that were used were: Harris Design-2 (Howmedica, Rutherford, NJ) in 68 hips; Bateman (Aufranc Turner) (Howmedica) in 65 hips; Osteonics (Allendale, NJ) in 34 hips; Charnley (DePuy, Warsaw, IN) in 19 hips; Harris Precoat (Zimmer, Warsaw, IN) in 10 hips; CAD (Howmedica) in eight hips; 60/32 (Zimmer) in three hips; Matchett Brown (3M, St Paul, MN) in two hips; Moore (3M) in one hip; Moore Leinbach in one hip (3M); and Protosul 10 (De Puy) in one hip. Several bipolar component designs were used during this period including: Bateman (Howmedica) components in 158 hips, UHR (Osteonics) in 38 hips, Zimmer bipolar components in nine hips, and Howmedica bipolar components in seven hips.

The outer cup size was determined by measuring the femoral head and then doing trial reductions to confirm the largest concentric stable fit in the acetabulum. Stems were cemented using handpacking techniques (first generation) in 190 hips (89.6%) and medullary canal plug and pressurization (second generation) in 22 hips (10.4%). A medullary canal vent tube was used in 29 hips (13.7%).

Perioperative antibiotics and prophylactic anticoagulation with low-dose Coumadin (DuPont Pharma, Wilmington, DE) were used routinely. Ambulation with weightbearing as tolerated usually was initiated on the first or second postoperative day. Patients initially used a walker and then progressed to using crutches or a cane as tolerated.

Four patients who did not have reoperation died; however, additional clinical data (1.9%) on those patients were not available. Eleven patients died in the hospital or within 30 days of surgery. Therefore, the mean clinical followup for the remaining 190 patients (197 hips) was 5.8 years (range, 51 days–19.4 years). Twenty-six patients were alive at last review and had not had a reoperation. The mean clinical followup for these patients was 11.7 years (range, 5.3–16.8 years).

Acetabular protrusio and cartilage erosion were assessed and measured using the criteria of LaBelle et al. 30 Acetabular protrusio was assessed by measuring medialization of the acetabular line compared with the normal hip or radiograph of the hip obtained immediately postoperatively. The more clearly visible of either Kohler’s line or the ilioischial line was used as a reference point. Acetabular cartilage erosion was determined by measuring the change in thickness of the acetabular cartilage compared with that seen on the radiographs obtained postoperatively or compared with ½ the joint cartilage of the normal hip. Femoral component subsidence was determined by comparing measurements from the prosthesis collar to the lesser trochanter. Radiographic femoral loosening was recorded by measuring radiolucencies at the prosthesis-cement or cement-bone interface in the seven zones of Gruen et al. 23 Fixation of the femoral component was evaluated according to the method of Harris et al. 24 A radiolucent line occupying 50% to 99% of the bone-cement interface was considered to indicate possible loosening; a complete radiolucent line at the bone-cement interface indicated probable loosening; and migration of the component or fracture of the cement mantle indicated definite loosening. Evidence of debonding between the implant and cement and a radiolucent line that was less than 2 mm wide between the shoulder of the prosthesis and the cement were not considered to indicate loosening. Heterotopic ossification was recorded using the classification system of Brooker et al. 6 Radiographs were reviewed in a nonblinded fashion by all three authors.

Survival of the hemiarthroplasty was defined as the prosthesis not being removed or exchanged. Kaplan-Meier survivorship curves 28 were calculated using four end points: free of reoperation for any reason; free of revision for aseptic femoral loosening or acetabular wear (mechanical failure); free of revision for aseptic femoral loosening; and free of revision for acetabular wear. Survivorship free of aseptic femoral loosening or acetabular wear (mechanical failure) also was calculated by stratifying for age at operation and gender. Mortality rates at 30 days, 1 year, 2 years, and 5 years were calculated and compared with expected rates calculated for white people living in the central northwest.

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RESULTS

Eleven of 212 patients had associated injuries (5.2%). All patients with associated injuries had ipsilateral upper extremity fractures. The most common associated injury was the ipsilateral distal radius fracture (nine patients). Three patients had proximal humerus fractures and one had an ipsilateral open forearm fracture. The mean operating time was 104 minutes (range, 30–235 minutes). The mean estimated blood loss was 513 mL (range, 50–3000 mL).

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Mortality

There was one intraoperative death (0.47%). Shortly after implant cementation (no pressurization or vent used) the patient became hypotensive and subsequently asystolic. Resuscitative efforts failed. Postmortem analysis revealed the cause of death as hypotension with no evidence of pulmonary embolism or fat embolism. Including the intraoperative death, 11 patients died during their stay in the hospital or less than 30 days postoperatively, for a 30-day mortality of 5.2%. The causes of death were identified as ruptured abdominal aortic aneurysm in one patient, urosepsis in one, massive stroke in one, probable pulmonary emboli in two, pseudomonal sepsis and adult respiratory distress syndrome in one, congestive heart failure in three, and respiratory failure in one patient who had long-standing chronic obstructive pulmonary disease. Mortality at 1 year was 12.3%, at 2 years it was 20.9%, and at 5 years it was 44.4%; all were statistically above the predicted population-based mortality rates for white people living in the central northwest (p < 0.001).

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Reoperations

There were 10 reoperations (4.7%): five for aseptic femoral component loosening; three for deep periprosthetic infection; one for chronic dislocation; and one for symptomatic acetabular cartilage wear. The mean time to reoperation was 46.1 months (range, 4–156 months). Five of the 10 reoperations were done in the first 2 years after the original arthroplasty. The five patients with aseptic femoral loosening and the patient with symptomatic acetabular wear had revision of their hemiarthroplasties to total hip arthroplasties. One patient with a deep infection was treated with debridement and primary exchange to a total hip arthroplasty with antibiotic impregnated cement. Two patients were treated with resection arthroplasties and were not treated with subsequent reimplantation because of medical comorbidities. One patient had a recurrent dislocation and returned 6 months later with a chronically-dislocated prosthesis with a painful pseudoacetabulum; a resection arthroplasty was done. None of the 10 patients with a preoperative diagnosis of rheumatoid arthritis required reoperation.

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Clinical Results

Of the 161 patients who survived at least 2 years at last followup, 154 (95.6%) had no or slight pain, six (3.7%) had moderate pain (requiring occasional nonnarcotic analgesics), and one (0.7%) had severe pain (activity-limiting or requiring narcotic analgesics). Of the 26 patients with surviving implants who were alive at last review, 25 patients (96.2%) had no or slight pain, and one patient (3.8%) had moderate pain. The patient with moderate hip pain had no evidence of loosening or acetabular cartilage wear radiographically.

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Radiographic Results

Of the 161 patients who survived a minimum of 2 years, 55 (34%) had minimum 2-year radiographic followup. Excluding the 10 patients who had revision surgery, 30 hips in 45 patients (66%) had no radiographic acetabular cartilage erosion, 14 hips in 45 patients (32%) had 1 mm or less erosion, and one hip (one patient) (2%) had 1 to 2 mm erosion. No patients had acetabular protrusio.

Of the 45 surviving arthroplasties in 45 patients, five femoral components were possibly loose (11%), four were probably loose (9%), and one was definitely loose (2%). The patient with the definitely loose stem had severe thigh pain, but refused revision surgery because of her advanced age. Of the 26 living patients with surviving implants, 12 had radiographic followup greater than 2 years with a mean followup of 7.6 years (range, 4.7–13 years). Of these, 11 hips (11 patients) (91.7%) were not loose, and one (one patient) (8.3%) was possibly loose. Ten hips in 12 patients (83.3%) had no acetabular erosion and two hips in 12 patients (16.7%) had evidence of erosion of 1 mm or less. Heterotopic ossification was present in 32 of 55 patients (58%). There were 27 patients (49%) with Brooker Type I heterotopic ossification, four patients (7%) with Type II heterotopic ossification, one patient (2%) with Type III heterotopic ossification, and no patients with Type V heterotopic ossification.

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Survivorship Analysis

Kaplan-Meier survivorship of components in patients who did not have reoperation for any reason (with 95% confidence intervals) was 95.1% (range, 91.6%–98.5%) at 5 years, 93.6% (range, 88.9%–98.1%) at 10 years, and 89.2% (range, 77.4%–99.2) at 15 years (Fig 1). The survival free of revision for mechanical failure of the implant (aseptic loosening or acetabular cartilage wear) was 97.4% (range, 94.8%–100%) at 5 years, 95.9% (range, 91.8%–99.8%) at 10 years, and 91.3% (range, 79.6%–100%) at 15 years (Fig 2). The survival free of revision because of aseptic femoral loosening was 98% (range, 95.7%–100%) at 5 years, 96.5% (range, 92.5%–100%) at 10 years, and 91.9% (range, 80.2%–100%) at 15 years (Fig 3). The survival free of revision because of acetabular wear was 99.4% (range, 97.9%–100%) at 5 years, 99.4% (range, 97.3%–100%) at 10 years, and 99.4% (range, 95%–100%) at 15 years (Fig 4).

Fig 1.

Fig 1.

Fig 2.

Fig 2.

Fig 3.

Fig 3.

Fig 4.

Fig 4.

The survival free of revision for aseptic loosening or acetabular wear (mechanical failure) was analyzed as a function of patient age at the time of the operation. The 10-year survival for patients 60 to 69 years was 87.2% (range, 72.9%–100%), for patients 70 to 79 years it was 97% (range, 91.1%–100%), and for patients 80 years or older it was 100%. The difference in survivorship for the age groups approached, but did not reach statistical significance (p = 0.10). Survival free of revision for aseptic loosening or acetabular cartilage wear (mechanical failure) also was analyzed according to gender. For women, implant survivorship at 10 years was 95.2% (range, 90.4%–99.8%). For men, implant survivorship at 10 years was 100%. All reoperations were done on women but the difference was not statistically significant (p = 0.30).

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Complications

There were eight intraoperative complications (3.8%): one stroke, two trochanteric fractures treated with wiring, one atrial arrhythmia responsive to medication, one return to surgery immediately for removal of a retained sponge, and two episodes of transient hypotension in patients who subsequently had a myocardial infarction after surgery. One stem required revision at the time of the index procedure because the cement cured before complete seating of the component. During cement removal, a femoral perforation occurred proximally. A standard stem was cemented into place.

Excluding the 11 patients who died within 30 days of surgery, 23 (10.8%) patients had postoperative complications. There were four dislocations (1.9%). Three were posterior and one was anterior; two had been done through an anterior approach and two were done through a posterior approach. All patients initially were treated successfully with closed reduction and the use of a brace. No component disassembly occurred. There were four gastrointestinal complications (three patients required endoscopy), five myocardial infarctions for which the patients were treated medically, and four atrial arrhythmias for which three patients were treated medically and one required cardioversion. There were two apparent pulmonary emboli and one deep venous thrombosis for which the patients were treated with anticoagulation. There were two incomplete peroneal nerve palsies presumed to be pressure-related, which were treated with observation with eventual improvement. There was one late periprosthetic femur fracture at the tip of a well-fixed stem secondary to a fall. This patient was treated with skeletal traction and the fracture healed without complications. There was one patient with meningitis and one patient with pneumonia; however, both patients were treated successfully with intravenous antibiotics.

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DISCUSSION

The preferred treatment for displaced femoral neck fractures in elderly patients is controversial. A recent metaanalysis by Lu-Yao et al 38 of 106 published reports found an approximately threefold increase in reoperation if internal fixation was used compared with hemiarthroplasty for displaced femoral neck fractures in patients older than 65 years. In patients who received internal fixation, 33% had nonunions and 16% had avascular necrosis. When comparing unipolar with bipolar hemiarthroplasties, the same authors found the rate of reoperation for patients with unipolar hemiarthroplasties was double that of patients who had bipolar hemiarthroplasties. Ambulatory capacity and pain relief also was better in the patients with bipolar hemiarthroplasties. Dislocation rates were similar, 2.1% for patients with unipolar hemiarthroplasties and 2.9% for patients with bipolar hemiarthroplasties. Total hip arthroplasty, despite providing excellent pain relief and improving ambulatory capacity, had a worrisome dislocation rate of 10.7%, which has been substantiated by Lee et al. 31

Much of the literature on uncemented unipolar prostheses presents concerning rates of failure. Kofoed and Kofod 29 followed 71 patients with a mean age of 82.5 years for 2 years. Overall, 37% of patients had poor results and needed total hip arthroplasty. Of active patients, 55% needed total hip arthroplasty. Acetabular degeneration was the most common reason for failure. They concluded that active patients, regardless of age, should not be treated with an Austin Moore type implant. Other authors 14,21,38,41,44,47,56 also found problems with the Austin Moore type implant regarding reoperation rates and function. The data for cemented unipolar prostheses also have been reported. D’Arcy and Devas 9 studied a series of 354 cemented Thompson hemiarthroplasties in patients with a mean age of 81 years. Of the 156 survivors available for review at 3 years, there was an 18.9% failure rate. The most common reason for failure was acetabular erosion (11%). Maxted and Denham 42 reported on 92 patients treated with cemented Thompson prostheses with a mean followup of 4 years. They reported an age-dependent 19% revision rate, with younger patients having more failures. Other authors 4,38,50,56 have reported similar results.

The bipolar prosthesis was developed in 1974 3 in an attempt to provide a low friction inner bearing to decrease acetabular wear and to avoid acetabular resurfacing. Early results with the bipolar implant were encouraging, and subsequent reports showed a high percentage of satisfactory results. 3–5,9–13,15,16,18–20,22,27,30,33,36–40,45,50,51,53,55 The reported rates of protrusio and symptomatic acetabular wear were lower than those reported for unipolar prostheses, 3–5,9–13,15,16,18–20,22,27,30,33,36–40,45,50,51,53,55 although prospective randomized trials were not done. An added advantage was the low dislocation rate of these implants. 2,31,38 Goldhill et al 22 reported on 246 cemented bipolar hemiarthroplasties with a followup from 1 to 6 years. Seventy-seven percent of the patients returned to their prefracture level of function. The dislocation rate was 0.9%, and there were no revisions secondary to aseptic femoral component loosening or acetabular wear. LaBelle et al 30 reported on 128 cemented Bateman hemiarthroplasties for acute fracture of the femoral neck with a followup from 5 to 10 years. They had 49 living patients at last review with a mean followup of 7 years. Ten percent of patients required revision surgery, but there were no cases of acetabular protrusio, and 88% of the patients with surviving implants had no or slight pain. Other authors reported similar results with short- and intermediate-term followup. 11–13,18–20,27,33,37,40,50,53,55

Comparison studies for unipolar and bipolar prostheses have provided mixed results. Yamagata et al 56 compared 682 fixed-head and 319 bipolar prostheses implanted for various diagnoses, using cemented and uncemented techniques. The mean age of the patients was 73 years. They concluded that the reoperation rates were higher in the patients with fixed-head prostheses (12.5%) than for the patients with bipolar prostheses (7.2%). They also showed a significantly higher survivorship for cemented implants, regardless of head type. The Harris hip scores were better for the patients with bipolar prostheses. Other authors 14,38,44,47 also have reported better function and lower reoperation rates with bipolar implants. Some authors, however, have not found a significant difference in function between patients with unipolar and bipolar implants. 12,41,54

The current long-term survivorship study indicates that only a small number of cemented bipolar prostheses (4.7%) were removed or revised for any reason, and the majority of patients (95.7%) had no or slight pain. The low rate of dislocation (1.9%) supports the findings of Barnes et al. 2 No patients in the current study had acetabular protrusio. This is consistent with previous studies of cemented bipolar prostheses by Long and Knight, 37 Mannarino et al, 40 and LaBelle et al 30 in which no protrusio occurred. Acetabular cartilage wear was not a major problem with the bipolar design in this group of exclusively older patients, unlike many reports on unipolar implants. 4–9,11,21,29,38,41,42,44,47,49,52,54,56 Although earlier studies with older designs showed unpredictable motion at the inner bearing, 7,8,13,43 one study using contemporary implants showed preservation of motion at the inner bearing in 93.2% of 117 hips evaluated fluoroscopically at a mean of 46.5 months postoperatively. 25 Additionally, the motion did not seem to deteriorate with time. Inner bearing motion may be successful in reducing the incidence of acetabular wear, as the developers of the prostheses theorized. 3

The current data also support the conclusions of LaBelle et al 30 in that the primary problem in the long-term survivorship of cemented bipolar prostheses is femoral component loosening. Cement techniques and femoral implants varied at the authors’ institution during this time, with most cases done with first generation techniques. It is possible that improvements in cementation techniques and stem designs may continue to improve the longevity of these prostheses. Some authors have advocated uncemented bipolar hemiarthroplasty; however to date, the clinical results favor cemented fixation of the femoral component. 16,17,30,32,35,36,48,51,56

The current data showed a significant (p < 0.001) increase in mortality in the patients with femoral neck fractures at 1, 2, and 5 years when compared with expected rates for a general matched population. The current morbidity and mortality rates likely are affected by the nonelective nature of the surgery and the medical comorbidities of this patient population. Nather et al 46 found that 58% of patients who had hemiarthroplasty had medical comorbidities. Their 3-month mortality was 6% and 12-month mortality was 15%. Jalovaara and Virkkunen 26 reviewed 185 patients who had hemiarthroplasty and compared them with aged-matched control subjects without fractures. The mortality was 12% above controls at 3 months, 19% at 12 months, and 21% at 18 months.

A weakness of the current study is the low rate of long-term radiographic followup. Despite the fact that all patients routinely were asked to have radiographs obtained at 1, 2, 5, 10, 15, and 20 years, many patients declined these requests. Difficulties in this elderly patient population with comorbidities include transportation problems and costs. Many patients respond by questionnaire stating their hips were asymptomatic and they did not wish to return or send radiographs. Additionally, the method of assessing acetabular cartilage wear radiographically has potential inaccuracies, some patients did not have immediate postoperative radiographs available and the contralateral normal hip was used for comparison. Despite the incomplete radiographic followup in many patients, the excellent survivorship of these implants and a low rate of pain at last followup confirm the efficacy of these implants for the lifetime in the majority of elderly patients studied.

The current data show that cemented bipolar hemiarthroplasty done for a diagnosis of acute femoral neck fracture is associated with excellent component survivorship in the elderly patient. The majority of patients died with the implant in place and functioning well. The rate of reoperation and complications, most notably dislocation, was low. The arthroplasty provided satisfactory pain relief for the lifetime of the majority of elderly patients after femoral neck fracture. To the authors’ knowledge, this series represents the largest survivorship study of exclusively cemented bipolar hemiarthroplasties for acute displaced intracapsular femoral neck fractures in elderly patients.

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