Mar 09

Proximal Femoral Reconstruction With a Constrained Acetabulum in Oncologic Patients

Proximal Femoral Reconstruction With a Constrained Acetabulum in Oncologic Patients

Muhammad Umar Jawad, MD; Earl W. Brien, MD

Orthopedics
February 2014 – Volume 37 · Issue 2: e187-e193
DOI: 10.3928/01477447-20140124-24

Abstract

Metallic endoprostheses are used for oncological reconstruction around the proximal femur and hip joint. Common modes of failure with hemiarthroplasty or standard hip arthroplasty after proximal femoral replacement include dislocation, late hip pain, and infection. The authors reviewed hospital records to identify patients undergoing constrained tripolar hip arthroplasty for oncological reasons between 2002 and 2012. Inclusion criterion was at least 12-cm proximal femoral resection, including patients with total femur reconstruction. A total of 33 patients were reviewed. Information regarding demographics, length of follow-up, treatment characteristics, and patient outcomes was extracted. Average follow-up for all patients was 912.33 days (30.4 months). Average follow-up was 1396.1 days for living patients and 428.6 days for deceased patients. Average estimated blood loss was 462.12 cc: an average of 1080 cc for patients undergoing total femoral resection and replacement and 315.8 cc for patients undergoing proximal femoral resection and replacement. Average operative time was 137.7 minutes: an average of 205 minutes for patients undergoing total femoral resection and replacement and 119.1 minutes for patients undergoing proximal femoral resection and replacement. Average Musculoskeletal Tumor Society score was 21.7. There were no dislocations in the cohort. A constrained tripolar device can be safely used for oncological proximal femoral reconstructions while minimizing the risk of dislocation. Positioning of the acetabular implant in neutral anatomic version in conjunction with a neutral-placed femoral component provides the greatest range of motion, reduction of liner impingement, and improved hip stability.

The authors are from the Department of Orthopedic Surgery, Cedars-Sinai Medical Center, Los Angeles, California.

Dr Jawad has no relevant financial relationships to disclose. Dr Brien is a consultant for Howmedica/Stryker.

Correspondence should be addressed to: Earl W. Brien, MD, Department of Orthopedic Surgery, Cedars-Sinai Medical Center, 8700 Beverly Dr, Los Angeles, CA 90048 ( earl.brien@cshs.org).
Received: August 26, 2013
Accepted: September 26, 2013
Posted Online: February 07, 2014

The first case of endoprosthetic reconstruction for a bone neoplasm was reported in 1942.1,2 Poor long-term survival rates for patients with bone neoplasm involving extremities limited any attempts at limb salvage until the introduction of chemotherapy in the 1970s.3,4 Today, limb salvage is attempted in up to 80% to 90% of patients with musculoskeletal malignancies.5Metallic endoprosthetic reconstruction has been the preferred method recently because improved design and modularity of components and methods of fixation allow for a quicker return to function.5–8

Despite the advantages, implant failure rates as high as 24.5% have been reported.9 Henderson et al9 described 3 mechanical and 2 nonmechanical modes of failure. Among mechanical modes of failure, soft tissue failure (type 1) (ie, instability, tendon rupture, or aseptic wound dehiscence) was the most common mode of failure around polyaxial joints (ie, hip and shoulder). Of 403 procedures around the proximal end of the femur, a total of 64 failures were reported. The most common mode of failure was type 1.9 Dislocation rates as high as 10.9% and 4.6% have been described for hemiarthoplasty and endoprosthetic reconstruction of proximal femur for oncological reasons, respectively.5,10 These rates were significantly higher than when the same reconstruction method was used for nononcological reasons.9,10 Thus, instability is a major issue surrounding the endoprosthetic reconstruction for the proximal femur for oncological reasons. Furthermore, with increasing long-term survival and demand, hemiarthroplasty can result in subsequent groin pain requiring revision to total hip arthroplasty (THA).10 Standard THA in patients with proximal femoral replacement lacking hip abductor function has resulted in an unacceptably high rate of hip dislocation.5

The current authors sought to determine whether a constrained hip system can be used to treat instability associated with oncological reconstructions around the hip. The rarity of the condition precludes the possibility of a case-control study at their institution. Thus, this article presents an observational study investigating the incidence of hip dislocation after using a constrained system for oncological reconstruction. Because most dislocations occur 6 months postoperatively,11–19 the current authors defined success as dislocation-free survival for at least 6 months postoperatively or the end of the patient’s life, only if death occurred for unanticipated and unrelated medical reasons. Furthermore, the authors sought to determine whether there is a need for modification of the surgical technique and/or relative version of femoral and acetabular components when using the constrained hip system for oncological reconstructions. It is noteworthy that constrained hip systems have been used extensively to treat patients with instability for nononcological conditions.11–19 However, controversy exists regarding whether it is the ideal system to treat instability.20–26 The current authors compare their results with outcomes from the adult reconstruction literature. To their knowledge, this is the first report evaluating constrained hip reconstruction exclusively in oncologic patients after massive bone resection. Others have tried to address this issue, but the results included other methods in addition to the constrained hip reconstruction systems.

This article presents the outcomes of proximal femoral reconstruction for massive bone loss using a constrained hip system. The device has been approved by the US Food and Drug Administration for oncologic reconstructions. All surgeries were performed by the senior author (E.W.B.).

Materials and Methods

A total of 39 patients with a constrained hip reconstruction performed by the senior author between 2002 and 2012 were retrospectively identified. Five patients were excluded from the final analysis because a constrained hip system other than the senior author’s most commonly used system was used. Moreover, these cases had cups that were in place from previous THA and thus were a different population of patients. That resulted in 34 patients with a constrained hip system used for endoprosthetic reconstruction of the proximal femur for oncological reasons during the past 10 years. Another patient was excluded because he was lost to follow-up after 5 years, resulting in a final cohort of 33 patients. Inclusion criteria included resection of at least 12 cm of proximal femur, which translates into the absence of hip abductors and psoas muscle insertions.

Mean patient age was 55 years (range, 21–93 years). Female:male ratio was 17:16. Of 33 patients, 17 were alive and 16 had died.

Follow-up period was calculated in days from the date of surgery to the date of last follow-up. All living patients were requested to visit the senior author’s office for a follow-up visit. If for some reason that was not possible, a telephone interview was conducted. For all deceased patients, follow-up was calculated from the date of surgery to the date of last visit to the office. Musculoskeletal Tumor Society (MSTS) forms were administered as an outcome measure, and all reported scores were from the last office visit. Estimated blood loss and operative time were calculated retrospectively from intraoperative nursing records.

The indications for surgery were divided into 3 categories: (1) bone metastasis recalcitrant to treatment/impending pathologic fracture; (2) salvage procedure for recurrence or failure of primary implant; and (3) primary malignancy. Each case was classified as one of these categories. All patients with a primary procedure for a malignant process other than a primary bone malignancy were classified as category 1. Patients with a previous surgical procedure at the same site for the malignant process were classified as category 2. Patients with a primary bone malignancy with no previous history of surgical resection or reconstruction were classified as category 3.

Pre- and postoperative radiographs showing a representative case from each category are provided (Figures 13). Patients undergoing total femoral replacement with a constrained hip were also included in the analysis. Figure 4represents a patient with total femoral replacement.

Figure 1:

Preoperative coronal computed tomography scan showing destruction of the proximal femur by metastatic hepatocellular carcinoma (A). Postoperative anteroposterior radiograph showing proximal femoral replacement and a GMRS proximal femur and tritanium cup (Howmedica/Osteonics, Mahwah, New Jersey) in a neutral position (B).

Figure 2:

Anteroposterior radiograph showing implant failure in a patient with metastatic lung cancer who underwent internal fixation and radiation for proximal femur fracture. The patient developed nonunion and implant failure (A). Postoperative anteroposterior radiograph showing revision with proximal femoral replacement and a GMRS proximal femur and tritanium cup (Howmedica/Osteonics, Mahwah, New Jersey) in a neutral position (B).

Figure 3:

Preoperative sagittal computed tomography scan showing destruction of the femoral head by clear cell chondrosarcoma (A). Postoperative anteroposterior radiograph showing proximal femoral replacement and a GMRS proximal femur and tritanium cup (Howmedica/Osteonics, Mahwah, New Jersey) in a neutral position (B).

Figure 4:

Preoperative sagittal computed tomography scan showing osteolysis of the femoral neck around the intramedullary nail. Recurrence and soft tissue seeding developed lateral to the hip abductors after another physician used an intramedullary nail to treat the pathological fracture associated with osteosarcoma (A). Postoperative sagittal computed tomography scan showing the patient revised to a total femur and a GMRS proximal femur and tritanium cup (Howmedica/Osteonics, Mahwah, New Jersey) in a neutral position (B).

All cases had a primary cup with a constrained liner with an intact acetabulum. Soft tissue reconstruction was performed in all cases. All surgeries were performed using the lateral approach to the hip. The hip abductors were anchored to the holes of the prosthesis using Mersilene tape (Ethicon, Somerville, New Jersey) in a modified Bunnell stitch. The iliotibial band was closed separately with interrupted #1 Ethibond suture (Ethicon). The acetabulum was reamed and placed in an anatomic position, and the femur corresponded to the cup in anteroposterior version to achieve maximum range of motion and minimize impingement. All patients had multiple screws with maximum fixation placed in the superior and posterior acetabulum. However, a few cases had additional screw fixation carefully placed to avoid injury to external iliac vessels. The postoperative protocol was out of the bed 3 times on postoperative day 1 and weight bearing as tolerated, provided the fixation was adequate. Although total hip precautions are used with physical therapy initially, full weight bearing was initiated, and either pillow or abduction pillow was used for comfort and discontinued at the patient’s request (usually during hospitalization).

Statistical analysis was performed using Student’s t test. Musculoskeletal Tumor Society scores were used for postoperative evaluation.27

No research funding was obtained from an external source to conduct this study. The study was approved by the ethics committee of the authors’ institution.

Results

The patients’ charts were retrospectively reviewed to collect relevant information. Demographics are summarized in Table 1, and treatment characteristics are outlined in Table 2. A total of 33 patients with 33 constrained hips were analyzed. Average follow-up for all patients was 912.33 days. Average follow-up was 1396.1 days for living patients and 428.6 days for deceased patients. There was no surgery-related mortality in the cohort. However, 3 patients died shortly after surgery due to unanticipated medical reasons. Their surgical courses were uneventful. Follow-up for these 3 patients was limited to 10, 13, and 35 days, respectively, and they were classified as category 1, 2, and 3, respectively.

Table 1:

Patient Demographics

Table 2:

Treatment Characteristics

Average estimated blood loss (EBL) was 462.12 cc (range, 200–2000 cc). Patients undergoing total femoral resection and replacement had an average EBL of 1080 cc, with 2 such patients losing 2000 cc and 1800 cc, respectively, intraoperatively. Average EBL for patients undergoing proximal femoral resection and replacement was 351.8 cc. Compared with patients undergoing total femoral replacement, patients undergoing proximal femoral resection and replacement had significantly less EBL (P=.049).

Average operative time for the entire cohort was 137.7 minutes (range, 63–322 minutes). When stratified for patients undergoing total femoral resection and replacement, average operative time was 205 minutes. Patients undergoing proximal femoral resection and replacement had an average operative time of 119.1 minutes. The difference was statistically significant (P=.036).

The cohort can be divided into 3 categories with respect to histopathological diagnoses. Eighteen patients had carcinoma metastases involving the proximal femur. Six patients had primary soft tissue sarcoma in close proximity to the proximal femur or metastases originating from primary soft tissue sarcoma (n=2). Nine patients presented with primary bone malignancy. The most common diagnoses in the cohort were breast cancer metastasis (n=8) and osteogenic sarcoma (n=7).

Indications for surgery were also classified into 3 categories, as previously discussed. Category 1 comprised 12 patients, category 2 comprised 17 patients, and category 3 comprised 4 patients.

A majority of patients (n=24) underwent cemented fixation of the femoral stem. Six patients underwent total femoral replacement. Cementless press fit implants were used in 3 patients.

Prior treatments included dynamic hip screw in 5 patients, intramedullary nailing in 6 patients, femoral replacement as a part of hemiarthroplasty in 1 patient and THA in 3 patients, allograft reconstruction in 1 patient, and wide local excision in 2 patients. A total of 15 patients had no prior treatment, and 1 patient had previous intramedullary nailing and an attempted salvage with a femoral replacement.

Many constrained devices generate areas of increased stress at the implant-bone interface and are prone to loosening, leading to failure. All patients in this cohort were routinely analyzed using standard radiographs at follow-up. No evidence of loosening was found at the femoral and/or acetabular side at most recent follow-up.

Average MSTS score was 21.7 (range, 28–19). Two patients reported mild to moderate antalgic gait; however, Trendelenburg gait was not seen in any patient.

Discussion

Reconstructive options for the proximal femur after massive bone loss include hemiarthroplasty and THA with a large head and dual-mobility or constrained acetabular liner. After the proximal femur is resected, the hip abductors can be anchored down to the prosthesis and/or secured to the lateral fascia. However, despite such reconstructions, significant loss of abduction strength occurs, commonly characterized clinically by a Trendelenburg gait. Consequently, when the abductor force is diminished, stability of the hip is compromised and dislocation may ensue.

Reconstruction with bipolar hemiarthroplasty has been well established in the treatment of patients after proximal femoral reconstruction.5,28 A review of the adult reconstructive literature revealed a mean follow-up of 51 months (range, 24–124 months) and a mean time to failure of 30.6 months (range, 19–44 months, where applicable).29 In the current cohort, the average follow-up of 30.4 months is significantly less than the mean follow-up reported in the review, and comparable to the mean time to failure. Because this study analyzes the failure rate of a constrained hip device in an oncologic population, a follow-up time comparable to mean time to failure is essential to the validity of this analysis. However, the current cohort of oncologic patients is fundamentally different from the adult reconstructive patient population analyzed in the review.29

If the capsule can be preserved and purse-stringed around the implant, stability is often not a concern despite compromised hip abductors. However, it has been well established in the literature that joint pain may occur late after hemiarthroplasty. In the current study, 1 patient who underwent hemiarthroplasty at another institution after resection for a proximal femoral osteosarcoma dislocated twice 9 months postoperatively and was subsequently revised to a constrained liner without complication. A second patient who underwent hemiarthroplasty at another institution remained stable after total femur resection but reported hip pain approximately 4 years postoperatively and was revised to a constrained THA with improved symptoms.

Constrained liners are numerous and include fully hemispheric locking ring mechanisms secured after the head has been reduced into the liner, modular head equatorial flats, and constrained tripolar devices. Failure rates for revision THA have been reported to be as high as 42% at a mean follow-up of 10.7 years.20 The most common modes of failure are head dislocation, liner dissociation, fixation failure, and polyethylene failure.

Prior failure rates for tripolar constrained components have been reported by Callaghan et al12 to be 6% in cases with liners without cementation and 7% in patients with cemented liners. Others have reported improved results with constrained liners.30 Kaper and Bernini31 reported 4 cases of failure of constrained acetabular prosthesis for instability. More recently, dual-mobility sockets have also been used with success to treat recurrent dislocation.32Despite the significant weakness of the hip abductors in the current study’s patients, there was a 0% dislocation rate. These results are comparable with those of Ruggieri et al,33 who reported a 0% dislocation rate in 23 cases of total femur megaprostheses. The current authors believe the most likely reason that this complication was not experienced in this study is primarily technical.

After proximal femoral resection, reaming and placement of the acetabular component is neutral to the anatomy of the patient’s acetabulum. No additional version is used, and the intraoperative acetabular positioning is significantly less (approximately 15°) than the standard placement of the acetabulum performed in THA. After the acetabulum has been reamed, the cup is placed anatomically so the overlap of the cup to the acetabular rim is symmetric. No change from the patient’s anatomic version is put into the cup, regardless of structural or morphologic changes of the acetabulum. In most cases, the acetabular cup is placed at approximately 15° to 20° of anteversion, which is the mean acetabular version when evaluating the upper- and mid-level version. A mean acetabular version of 15° to 20° is supported by Perreira et al,34 who performed multilevel measurement of acetabular version using 3-dimensional computed tomography–generated models and found that the mean upper- and mid-level acetabular anteversion values were 14.4°±10.5° and 21.3°±5.8°, respectively. Similarly, neutral abduction is also an important variable to avoid impingement. The femur is placed neutral to the acetabulum, and there is minimal anteversion in the stem. Intraoperatively, this relatively neutral positioning of both components allows for a greater range of motion without impingement of the neck on the liner. The current authors believe that patients undergoing revision after THA requiring a constrained liner for instability or dislocation will have less range of motion because of their initial positioning. In addition, posterior lip impingement is more likely to lead to dislocation.

This study has several limitations. It is an observational study without a control group, which precludes a comparison with other techniques. However, the authors attempted to address this problem by comparing their results with those from other institutions. Moreover, the sample size is small. It is also a single-center study, which can lead to a selection bias. However, because all surgeries were performed by a single surgeon (E.W.B.), consistency of the technique was ensured. Despite these limitations, the study highlights the necessity of performing a prospective trial using the surgeon’s technique for constrained hip to compare it with the other methods to address the issue of instability around the hip joint in the absence of hip abductors.

Conclusion

A tripolar constrained acetabular liner after proximal femoral resection is an excellent option that can provide stability and painless gait in patients after massive bone loss for tumors of the proximal femur with deficient hip abductors. Technical aspects are critical for improving stability and reducing impingement. Good to excellent function can be achieved with these complex reconstructions.

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10.3928/01477447-20140124-24

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