Cementless Calcar-Replacement Hemiarthroplasty Compared with Intramedullary Fixation of Unstable Intertrochanteric Fractures: A Prospective, Randomized Study

Kim, Shin-Yoon MD; Kim, Yong-Goo MD; Hwang, Jun-Kyung MD

Journal of Bone & Joint Surgery - American Volume: October 2005 - Volume 87 - Issue 10 - p 2186–2192
doi: 10.2106/JBJS.D.02768
Scientific Articles

Background: Unstable intertrochanteric fractures in elderly patients are associated with a high rate of complications. The purpose of this investigation was to compare the results of long-stem cementless calcar-replacement hemiarthroplasty with those of treatment with a proximal femoral nail for unstable intertrochanteric fractures in elderly patients.

Methods: Fifty-eight elderly patients with an AO/OTA type 31-A2 intertrochanteric fracture of the femur were randomized into two treatment groups and were followed for a minimum of two years. The twenty-nine patients in Group I were treated with a long-stem cementless calcar-replacement prosthesis, and the twenty-nine patients in Group II were treated with a proximal femoral nail. The two treatment groups were comparable with regard to demographic and injury variables.

Results: There were no significant differences between the groups in terms of functional outcomes, hospital stay, time to weight-bearing, or general complications. Patients treated with a proximal femoral nail had a shorter operative time, less blood loss, fewer units of blood transfused, a lower mortality rate, and lower hospital costs compared with those treated with the long-stem cementless calcar-replacement prosthesis.

Conclusions: In elderly patients with an unstable intertrochanteric femoral fracture, a proximal femoral nail provides superior clinical outcomes but no advantage with regard to functional outcome when compared with a long-stem cementless calcar-replacement arthroplasty.

Level of Evidence: Therapeutic Level I. See Instructions to Authors for a complete description of levels of evidence.

1 Department of Orthopedic Surgery, Kyungpook National University School of Medicine, Jung Gu Sam Duck 2 Ga 50, Daegu 700-721, South Korea. E-mail address for S.-Y. Kim: syukim@knu.ac.kr

Article Outline

The ideal implant for the treatment of an unstable intertrochanteric femoral fracture is still a matter of discussion. Elderly patients with osteopenia have a high prevalence of unsatisfactory functional results, with unacceptable shortening and external rotation deformity of the limb, following treatment of an unstable intertrochanteric fracture with a sliding screw1-5. To allow immediate postoperative weight-bearing without excessive collapse at the fracture site, some surgeons have advocated the use of prosthetic arthroplasty6,7 or an intramedullary hip screw8 in these patients. Several prospective, randomized studies have been performed to compare the results of treatment of intertrochanteric femoral fractures with a compression hip screw with the results of treatment with an intramedullary hip screw and a plate8,9. However, we are not aware of any prospective, randomized study comparing the results of treatment with an intramedullary hip screw with those of primary bipolar prosthetic arthroplasty. We report the results of a prospective, randomized study comparing the use of a long-stem cementless calcar-replacement hemiarthroplasty with the use of a proximal femoral nail in elderly patients with an unstable intertrochanteric fracture.

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Materials and Methods

Patient Population

Between November 1998 and May 2001, fifty-eight patients with an unstable comminuted intertrochanteric femoral fracture (AO/OTA10 type 31-A2 and Evans11 type III or IV) were enrolled in the study, which was approved by our institutional review board. All type-31-A2 fractures that had been caused by a low-energy injury in patients who were at least seventy-five years old were eligible for inclusion in the study. The majority of patients fell at home. We excluded patients with an AO/OTA type 31-A1 or A3 fracture.

After they provided informed consent, the patients were randomized into two treatment groups with use of computer-generated random numbers; no patient refused to participate in the study. Twenty-nine patients (twenty-three women and six men) (Group I) were treated with a long-stem cementless calcar-replacement hemiarthroplasty (Mallory-Head calcar-replacement stem; Biomet, Bridgend, United Kingdom). Twenty-nine patients (twenty-one women and eight men) (Group II) were treated with an intramedullary nail (proximal femoral nail [PFN]; Mathys Medical, Bettlach, Switzerland). The same surgeon performed the surgery for both arms of the trial. The two groups were comparable with regard to age, gender, and the osteoporosis index described by Singh et al.12 (Table I). The mean duration of follow-up was thirty-five months (range, twenty-four to fifty-eight months) in Group I and thirty-four months (range, twenty-four to fifty-seven months) in Group II. The use of prophylactic antibiotics was the same in the two groups. Prophylaxis against deep venous thrombosis was not administered in either group, as is customary for patients with hip fractures in Korea as a result of the low incidence of this complication.

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Implants

Mallory-Head Calcar-Replacement Stem

The Mallory-Head calcar-replacement stem has a circumferential porous coating and is available with 34, 45, and 55-mm proximal lengths to compensate for bone deficiencies in the proximal-medial portion of the femur. The overall length of the stem is either 220 or 260 mm, and the stem is bowed according to whether it is intended for a left or right femur. Stem diameters range from 9 to 19 mm, in 2-mm increments. The configuration of the calcar-replacement stem is enhanced proximally by an optional trochanteric transfixing bolt and plate, which allow the greater trochanter to be compressed against the prosthesis for enhanced fixation and proximal rotational stability. Each bolt is made of titanium alloy and is designed with a Spiralock thread (Leicestershire, England) and a polyethylene peg to help prevent backing out or separation (Figs. 1-A and 1-B).

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Proximal Femoral Nail

Figure. No caption a...
Figure. No caption a...

The proximal femoral nail (PFN) is made of titanium and is 240 mm in length. Two screws can be inserted into the femoral neck through the proximal part of the nail. The lower screw is an 11.0-mm load-bearing neck screw, the tip of which should be placed subchondrally into the distal half of the femoral head. The other screw, a 6.5-mm antirotational pin, is placed through the upper part of the nail into the proximal half of the femoral neck to prevent rotation of the head-neck fragment (Figs. 2-A and 2-B).

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Operative Technique

Mallory-Head Calcar-Replacement Stem

A posterolateral modified Gibson approach was used. Anteversion-retroversion of the prosthesis was determined with use of the posterior aspects of the medial and lateral femoral condyles as a guide during the procedure. The appropriate length of the stem was determined by comparing the center of the injured hip with the center of the contralateral, untreated hip with portable radiographic examination during the procedure. The proximal femoral cuts were fashioned by laying the cutting guide along the anterior aspect of the femur or by utilizing the trial prosthesis as a guide. As noted, the calcar prosthesis is available in three lengths (34, 45, and 55 mm) to accommodate for limb length and femoral offset. We used the 45-mm length in all patients because of the AO/OTA 31-A2 fracture type. It is necessary to have a stable platform on which to place the prosthesis. Once the prosthesis was in position, the point where the keel came into contact with the medial calcar was marked with methylene blue. The fractured greater trochanter was attached to the prosthesis with a trochanteric transfixing bolt and plate. We occasionally placed additional wires through the four-wire passage portals on the lateral side of the stem.

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Proximal Femoral Nail

The nail was implanted percutaneously, after closed reduction, under fluoroscopic control on the fracture table. The lower limb was placed in slight adduction to facilitate insertion of the nail. The proximal part of the femoral shaft was reamed manually with a 17-mm reamer. With the radiolucent aiming arm attached, the guidewire for the neck screw was introduced into the femoral neck in such a way that it would be located in the distal half of the neck as seen on the anteroposterior radiograph and centrally as seen on the lateral radiograph. The second, antirotational pin was then introduced. Static distal interlocking was then achieved with use of the aiming arm. Patients were allowed to get out of bed on the second postoperative day and to walk as soon as possible. They were allowed to bear full weight as tolerated with the aid of a walker or two crutches for six weeks postoperatively; they transitioned to a single cane or crutch in the second six weeks.

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Follow-up Protocol and Radiographic Evaluation

Follow-up evaluations were performed at six weeks; at three, six, and twelve months; and yearly thereafter. No patient was lost to follow-up. The radiographic evaluation was done by two independent observers (Y.-G.K. and J.-K.H.). Anteroposterior and lateral radiographs of the affected hip were made postoperatively while the patient was in the hospital and at each follow-up visit. We classified the quality of the reduction of the fracture as anatomical (<5° of varus or valgus and/or anteversion or retroversion), acceptable (5° to 10°), or poor (>10°)13. Vertical migration of the bipolar cup was measured along a perpendicular line from the hip center to the interteardrop line. Horizontal migration was assessed by measuring the distance from the teardrop to the intersection between a perpendicular line from the hip center and the interteardrop line. Erosion of the acetabular cartilage and horizontal or vertical migration of the bipolar cup of >2 mm were documented14. Stem stability was determined according to the criteria described by Engh et al.15 and was graded as optimal fixation, suboptimal fixation, or unstable fixation. A stem was considered to be unstable when there was progressive subsidence exceeding 3 mm, any change in position, a continuous radiolucent line wider than 2 mm, widening of the femoral canal, or a large distal bone pedestal. We recorded any intraoperative and postoperative complications related to the implant, the estimated blood loss, the number of units of blood that were transfused, the duration of the operation, the hospital costs, and the length of the hospital stay of each patient. Harris hip scores16 were determined postoperatively, and scores on an activities of daily living scale, the Mini-Mental State Examination (MMSE)17, and the American Society of Anesthesiologists (ASA) classification18 were determined before the operation and at each follow-up by the independent observers (Y.-G.K. and J.-K.H.).

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Statistical Analysis

Statistical analysis was performed with use of the Mann-Whitney U test and the Fisher exact test (version 10; SPSS, Chicago, Illinois). Differences were considered to be significant at the p < 0.05 level.

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Results

Detailed demographic data on both patient groups can be found in the Appendix. The treatment groups were comparable with regard to all measured prefracture variables, including age, gender, Singh osteoporosis index, and scores on the activities of daily living scale, the MMSE, and the ASA classification (Tables I and II). The intraoperative results are listed in Table III. Intraoperatively, there were no femoral shaft fractures or extensions of the original fracture. There were significant differences between the two treatment groups regarding blood loss, the number of units transfused, and the duration of the operation (p = 0.000). The immediate postoperative complications in both groups are presented in Table IV. Two patients in Group I died of myocardial infarction during the hospital stay. Six patients in Group I and four patients in Group II died within the first postoperative year. Eight patients in Group I and one patient in Group II died between the first and third postoperative years, but the causes of those deaths were not clearly established. The final mortality rate at three years was 55% (sixteen patients) in Group I and 17% (five patients) in Group II (p = 0.006).

The results of the fracture reduction and the times to union in Group II are presented in Table V.

The mean fluoroscopy time (and standard deviation) in Group II was 153 ± 5.4 seconds. There were no recurrent dislocations, no radiographic signs of loosening, and no acetabular erosion or migration in Group I. There were two trochanteric nonunions in Group I (Table VI). One trochanteric fragment was attached to the implant by the trochanteric transfixing bolt and plate, and the other nonunion was of the trochanteric tip. Neither appeared to influence abductor function clinically.

The patients in Group I were able to walk with a walker at a mean of 7.8 ± 1.6 days postoperatively, and those in Group II were able to do so at a mean of 8.8 ± 2.9 days (p = 0.069). The mean hospital stay was 13 ± 2.6 days in Group I and 11 ± 3.1 days in Group II (p = 0.144). However, the mean hospital cost was higher in Group I ($11,048 ± $1216) than in Group II ($5150 ± $821).

Three patients in Group II had a nonunion. Two had concomitant cutting-out of the hip screw, and they refused a reoperation. The third had concomitant breakage of the anti-rotatory screw and underwent conversion to a calcar-replacement implant. There were no femoral shaft fractures at the tip of the implant.

One bipolar cup dislocated in the immediate postoperative period, and the patient was treated with an abduction brace for two months without a recurrence. One patient in Group I had deep vein thrombosis, which was treated with low-molecular-weight heparin and warfarin. A patient in Group I had a common peroneal nerve palsy, which resolved incompletely after two years. One superficial infection in each group was successfully treated with antibiotics and frequent dressings. There were no complications related to the anesthesia. The functional scores did not differ between the two groups at the time of the latest follow-up (Table II).

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Discussion

Excessive collapse, loss of fixation, and cut-out of the lag screw resulting in poor function remain problems associated with internal fixation of unstable intertrochanteric fractures in elderly patients with osteoporotic bone. To allow earlier postoperative weight-bearing and to avoid excessive collapse at the fracture site, some surgeons have recommended prosthetic replacement, especially with a calcar-replacement or head and neck-replacement type of prosthesis, for the treatment of unstable intertrochanteric fractures6,7,19,20. Harwin et al.7 reported on fifty-eight elderly patients with osteoporosis in whom a comminuted intertrochanteric femoral fracture had been treated with a bipolar Bateman-Leinbach prosthesis and who were followed for an average of twenty-eight months. The average patient age was seventy-eight years, and 91% walked prior to discharge. Two patients had a nonunion of the greater trochanter. There were no deep infections, dislocations, acetabular erosions, or cases of stem loosening. Broos et al.6 reported on ninety-four elderly patients treated with a bipolar Vandeputte prosthesis. They found that the average operating time was shorter, the mortality rate was lower, and the functional results were better in the group treated with the bipolar hemiarthroplasty than in groups treated with Ender nailing, an angled blade-plate, or a dynamic hip screw.

Recently, Rodop et al.20 reported on fifty-four elderly patients who had been treated with a bipolar Leinbach hemiprosthesis (Protek; Sulzer Orthopedics, Baar, Switzerland). A good to excellent result, as assessed with the Harris hip-scoring system, was reported in 80% of the patients. There were no dislocations or cases of stem loosening.

We believed that a prospective, randomized trial, which had not been performed to our knowledge, was necessary to compare the results of primary bipolar hemiarthroplasty with those of internal fixation for the treatment of unstable intertrochanteric hip fractures.

In 1997, the proximal femoral nail (PFN) was introduced for the treatment of pertrochanteric femoral fractures. It was designed to minimize implant-related complications. Recent prospective clinical studies of the PFN21-24 showed cut-out rates ranging from 0.6% to 1.4% and a low tendency for varus displacement in comparison with that associated with other implants. No shaft fractures at the tip of the implant or mechanical failures of the implant were found in those studies. These remarkable clinical findings are supported by the results of biomechanical studies and by comparable in vitro investigations25-27. The weight-bearing capacity and implant stability of a dynamic hip screw (DHS; Synthes-Stratec, Oberdorf, Switzerland), a Gamma nail (Howmedica-Osteonics, Rutherford, New Jersey), and the proximal femoral nail (PFN) were tested in vitro, with use of static and dynamic loading, in unstable trochanteric fractures. The intramedullary devices were found to be several times stronger than the dynamic hip screw, with less or no deformity at maximum loads26. The authors of these biomechanical studies concluded that the intramedullary implants, when perfectly inserted, enable immediate postoperative and uncompromised mobilization under full weight-bearing conditions25,26.

In the present study, the cut-out rate of the hip screw of the proximal femoral nail was 7%. However, the patient age, fracture type, and duration of follow-up in this study differed substantially from those in the previous reports21-24. In previous uncontrolled studies19,20, primary bipolar arthroplasty was shown to result in a more rapid return to the preinjury level of activity, thus obviating the postoperative complications caused by limited activity or failure of the implant. In the present prospective, randomized study, the patients were well matched according to age, sex, preinjury health status, social dependency, Singh osteoporosis index12, and fracture type. All operations were performed by one surgeon at one center (S.-Y.K.). We inserted a cementless calcar-replacement femoral component because elderly patients generally have preexisting cardiac or pulmonary disease and insertion of a long-stem femoral component into a previously untreated canal may predispose a patient to cement-related cardiovascular complications28.

The present study had several limitations. First, it did not include a large number of patients. Second, the follow-up period was relatively short. Potential long-term problems associated with prosthetic replacement, such as loosening, acetabular erosion, stem failure, late infection, and late dislocation, may yet occur.

We found no significant differences between our two groups in terms of functional outcomes, hospital stay, and general complications. Longer-term studies with larger numbers of patients are necessary to identify any long-term advantage of a hemiarthroplasty with a long-stem cementless calcar replacement compared with treatment with the proximal femoral nail. However, our results showed no functional benefit of the arthroplasty at a minimum of two years postoperatively. Furthermore, compared with treatment with the proximal femoral nail, arthroplasty is more expensive, requires a longer operating time, and is associated with more blood loss and a higher mortality rate when used for the treatment of unstable intertrochanteric fractures in elderly patients.

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Appendix

Detailed demographic data on all study patients are available with the electronic versions of this article, on our web site at jbjs.org (go to the article citation and click on “Supplementary Material”) and on our quarterly CD-ROM (call our subscription department, at 781-449-9780, to order the CD-ROM). ▪

The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

Investigation performed at the Department of Orthopedic Surgery, Kyungpook National University School of Medicine, Daegu, South Korea

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