Keith R. Berend
With historical roots dating back nearly a century, hip hemiarthroplasty remains one of the most commonly performed orthopedic operations still in use today. Most hip hemiarthroplasty procedures are carried out for femoral neck fractures in elderly patients. Over the decades, however, hemiarthroplasty has been used for many other indications including initial usage for osteoarthritis and as a temporizing measure for the young patient with osteonecrosis. Hemiresurfacing procedures have been used to provide a conservative alternative to total hip arthroplasty in young patients. As longer-term data have become available, the future trends in the use of hip hemiarthroplasty and more specifically hemiresurfacing arthroplasty remain to be seen. This chapter outlines three categories of indications and patient types in which hemiarthroplasty is widely used. First is the use of hemiarthroplasty for the treatment of acute femoral neck fracture. Second, the use of hip hemiarthroplasty for indications other than femur fracture is reviewed. Third, the history and continued use of hemiresurfacing techniques will be analyzed. The future of this technique for indications other than proximal femur fracture will be written by long-term studies comparing and contrasting the effectiveness of hemiarthroplasty with the now available long-term results of total hip arthroplasty in these three patient groups.
Pathogenesis
Hemiarthroplasty and Femoral Neck Fracture
The prevalence of femoral neck fracture is rising. As the population ages, and the larger middle-age generation reaches elderly ages, this trend will no doubt continue. Optimal treatment of nondisplaced fractures includes internal fixation with bone screws and has been described as successful in multiple reports. Treatment of nondisplaced fractures with hemiarthroplasty has been associated with increased mortality; hemiarthroplasty and should be reserved for displaced fractures, which carry a higher rate of failure when treated with internal fixation. Once fracture displacement has occurred, the optimal treatment for the fracture has not been defined. Current controversy revolves around the use of cemented versus cementless femoral stem fixation, unipolar versus bipolar articulations, and the use of acute total hip arthroplasty (THA) versus hemiarthroplasty.
Treatment
Internal Fixation versus Hemiarthroplasty
The results of so-called “low-demand” monoblock uncemented unipolar hemiarthroplasty, such as the Austin Moore hemiarthroplasty (Fig. 11-1), have been reported to be inferior to those of other treatment options. Blomfeldt et al. 1 examined the functional outcomes of internal fixation and monoblock uncemented unipolar arthroplasty in a series of 60 patients with an average age of 84 years. In this group with displaced fractures, the overall mortality and complication rates were not statistically different between treatment options. There was a trend toward more reoperations in the internal fixation group, however, with 33% of the internal fixation group and 13% of the hemiarthroplasty group requiring subsequent surgery. The quality of life outcomes measures used in this study did demonstrate a clear superiority in those patients who lived longer than 2 years after index surgery and had undergone internal fixation. The authors concluded that when compared with internal fixation, there are few data to recommend the use of a low-demand uncemented monoblock unipolar design in elderly patients. This view has been supported elsewhere. In a randomized controlled series, El-Abed et al. 2 demonstrated superior functional results in their group of patients treated with internal fixation when compared with hemiarthroplasty. No difference in revision rates was seen, but both the patients' and the physicians' perception of outcome was better in the internal fixation group. The superiority of internal fixation seen in some studies should be tempered by the high rates of failure seen in other series. In the hands of experienced trauma surgeons, the failure rate and subsequent surgical rate is as high as 35% with only 67% of fractures achieving bony union without avascular necrosis at 2 years following surgery. In a separate report, nonunion is reported to occur in up to 30% of
P.82
cases with an additional rate of avascular necrosis occurring in up to 30% of displaced femoral neck fractures treated with internal fixation.
|
Figure 11-1 Photograph of an Austin-Moore hemiarthroplasty femoral component. |
Yau and Chiu, 3 using the same implant design concluded that its use should be avoided in younger active patients. Taken together, these data raise the question of the utility of either internal fixation or this type of uncemented monoblock unipolar design in the treatment of femoral neck fractures. Instead, other more durable designs and surgical options are indicated.
Cemented Femoral Fixation versus Cementless Fixation
Bezwada et al. 4 reviewed the clinical and radiographic outcomes of 256 cemented hemiarthroplasty devices inserted for acute femoral neck fracture over a 2-year period. All of the patients were older than 65 years of age. At an average of 3.5 years after surgery, there were two stem revisions and six cases converted to THA for recalcitrant groin pain. They concluded that cemented hemiarthroplasty is a viable treatment option with good midterm results in these elderly patients. Clearly, this 97% success far outweighs even the best reports of internal fixation or Austin Moore–type hemiarthroplasty for displaced femoral neck fractures. The use of a cemented device for hemiarthroplasty has been demonstrated to provide earlier and superior pain relief and return of function in some series. Further support for the use of a cemented hemiarthroplasty is provided by Dixon and Bannister. 5 In a review of 53 cemented bipolar hemiarthroplasties, they report that almost 70% of patients who were able to walk 1 mile before fracture were able to do the same at the time of final follow-up. Moreover, only two failures were noted in the series with 32-month follow-up. Nearly three decades ago, Beckenbaugh et al. 6 concluded that cemented hemiarthroplasty is indicated in the treatment of acute femoral neck fracture in the elderly. The cemented hemiarthroplasty still appears to be the standard to which other treatment options for displaced femoral neck fractures should be compared.
Caution is warranted, however, as the use of a cemented femoral device in the treatment of femoral neck fractures has been associated with an increased risk of death within 30 days of the surgery. Other risk factors associated with increased mortality following hip fracture treatment include female gender, advanced elderly age, pre-existing heart and lung conditions, and intertrochanteric-type fractures. It would seem prudent to weigh the possible increased risk of mortality with the benefit of earlier functional recovery when considering the use of cemented or cementless devices. Unfortunately, many of the low-demand, fracture-type stems are designed to be implanted either with or without cement, are made of cobalt-chrome, and do not have the same porous coatings that have proven to provide longevity in cementless applications. When these types of stems are implanted in a cementless fashion, the results will probably be inferior to those of cemented designs or modern porous coated stems (Fig. 11-2).
By avoiding revision for stem loosening into the second decade, primary femoral components with long-term excellent results should be the implant of choice when hemiarthroplasty is carried out for fracture. Certainly, in the younger, more active patient, this holds true.
Unipolar versus Bipolar Hemiarthroplasty
Several variables interplay in the decision between a unipolar and a bipolar prosthesis for use in hemiarthroplasty. The theoretical decrease in articular cartilage wear and increased range of motion with the bipolar device are frequently cited as the benefits obtained by choosing a bipolar design. Most frequently, cost containment is cited as the primary indication for use of a unipolar device.
Unipolar arthroplasty is a simple and cost effective approach to the surgical treatment of a displaced femoral neck fracture. More than 70% of people regain prefracture levels of ambulation, and 80% report mild or no pain at 1 year following surgery. Up to 80% survivorship at 7 years has been published with unipolar arthroplasty. There have been indications that stiffness, groin pain, cartilage degeneration, and acetabular protrusio are more frequent with unipolar designs compared with bipolar designs.
P.83
In older patients who are active, higher demands place increased stresses on the implant and articular surfaces leading to lower satisfaction with the surgical results in these cases.
|
Figure 11-2 Radiograph of a 62-year-old man who presented with a left hip cemented hemiarthroplasty for treatment of fracture that had failed after 3 years secondary to stem loosening and subsidence. |
Bipolar hemiarthroplasty has proven slightly superior to unipolar designs in some series. Although groin pain can and does still occur in some patients, a large meta-analysis of the literature revealed that 85% of patients report mild or absent pain and 85% regain functional mobility in the first 2 years after surgery. In a separate prospective series, no advantage to bipolar over unipolar designs was seen in elderly patients treated for femoral neck fracture.
As noted, an increase in stability may be conferred by the bipolar design, and this remains a significant motivator for its use. When the bipolar does dislocate, it more frequently requires open reduction than does unipolar hemiarthroplasty. In addition, there are several reports of wear, osteolysis, and loosening associated with the polyethylene articulation in bipolar arthroplasty. Taking the above noted information into account, it would appear that a well-designed cemented or porous coated femoral stem combined with a unipolar articulation would be the treatment of choice for the elderly, low-activity patient with a displaced femoral neck fracture. Total hip arthroplasty in the treatment of these fractures has been suggested to be the ideal treatment in younger patients and may eventually prove to be the ideal treatment for all patients with displaced fractures.
In addition to the standard application of a bipolar arthroplasty for femoral neck fracture, some investigators have attempted to use these devices as a conservative option when treating young patients with osteonecrosis (ON) of the femoral head. It is believed by some that not preparing the acetabulum and placing an acetabular component may be a beneficial option in these cases. This philosophy has been tested for several decades. In 1977 Beckenbaugh et al. 6 reported inferior results using the Thompson femoral endoprosthesis and cemented fixation in cases of ON. Again in the 1980s Lachiewicz and Desman 7 reported 52% fair and poor results using a bipolar endoprosthesis as a conservative option in young patients with ON. They further noted that younger age and increasing severity of the ON carried increased risk for failure.
Cabanela 8 repeated these negative results in a small meta-analysis highlighting the long-term results of cemented and uncemented bipolar hemiarthroplasties in contrast to THA. He noted that femoral loosening was not prevented by a bipolar design and that the results of THA in ON were far superior to those of the bipolar device. There were higher rates both of complications and reoperations in the hemiarthroplasty group. Lee et al. 9 prospectively compared the results of bipolar hemiarthroplasty versus THA using an identical modern cementless femoral component. They noted a significantly better pain score in the THA group. Groin pain occurred significantly more often in the bipolar group as did buttocks pain. In addition, 23% of the bipolar group demonstrated superior head migration and acetabular degeneration. Interestingly, the incidence of dislocation, thought to be a concern with THA for acute fracture, was the same in both groups. The conclusion of this series was that THA is a better procedure in patients with ON.
Better results have been reported by Grevitt and Spencer, 10 who studied hemiarthroplasty in renal transplant patients suffering from ON. In their series of 22 cemented bipolar hemiarthroplasties, all patients had improvements in pain and 21 of the 22 had good to excellent results. One case of aseptic loosening and one acetabular complication necessitated revision at an average of 40 months follow-up. Takaoka et al. 11echoed these acceptable results at early follow-up with the use of a bipolar device in ON. In a comparison of bipolar hemiarthroplasty with contralateral THA in the same patient, satisfactory results were equal between the sides. No statistical differences were noted in any of the clinical outcomes measured. The authors concluded that in young patients with Ficat stage III disease, a bone in-growth stem and bipolar arthroplasty is the treatment of choice. Excellent results have also been shown with the use of a bipolar device and an uncemented stem in young active patients with ON associated with sickle cell disease. Caution should be used in these cases and any scenario where acetabular bone stock may be involved because protrusion can occur, complicating conversion to THA when necessary. It appears that in selected cases of young patients with AVN, a bipolar articulation combined with a modern cementless femoral component can provide acceptable results for several years.
P.84
Surface Replacement Hemiarthroplasty
Total articular resurfacing arthroplasty procedures have gained and lost popularity several times in the relatively short history of hip arthroplasty. With more advanced bearing options, improved implantation techniques, and stringent patient selection, these procedures are enjoying a tremendous resurgence of interest worldwide. As total resurfacing initially fell from favor, owing to thin polyethylene acetabular surfaces and fixation issues, hemiresurfacing has remained a viable option in young patients with ON.
Although the theory of hemiresurfacing is quite attractive in the young active patient with ON, there have been negative reports in the literature. Cuckler and Tamarapalli 12 reported poor results but recommended this procedure in patients with ON if younger than 30 years of age as the conversion to THA is straightforward. Adili and Trousdale 13 reported similar poor results with overall survivorship of 76% at 3 years. Only 62.5% of cases reported satisfaction and good pain relief with this procedure.
As alternative bearings have become available, the role of selected hemiresurfacing has been questioned. Total resurfacing hip arthroplasty in ON has enjoyed renewed interest as results of this procedure are now being reported in a more favorable light. Beaulé et al. 14 have reported better functional results and better pain relief with the use of a metal-on-metal resurfacing than with hemiresurfacing alone.
Conclusions
Hemiarthroplasty continues to hold a strong position in the treatment of displaced femoral neck fracture in the elderly patient. Although some authors believe that total hip arthroplasty may be a better option, complications such as dislocation and increased operative time and blood loss may outweigh these benefits in the elderly low-demand patient. Both cemented and cementless fixation have shown good long-term results as have unipolar and bipolar designs. Advantages and drawbacks to each combination should stimulate personal investigation by the orthopedic surgeon as to his or her own outcomes. Hemiresurfacing arthroplasty has attractive theoretical advantages, but with alternative bearings and improved implant fixation options this procedure has decreasing and now very limited application.
Reference
Suggested Readings
Beaulé PE, Amstutz HC, Le Duff M, et al. Surface arthroplasty for osteonecrosis of the hip: hemiresurfacing versus metal-on-metal hybrid resurfacing. J Arthroplasty. 2004;19(8 suppl 3): 54–58.
Bezwada HP, Shah AR, Harding SH, et al. Cementless bipolar hemiarthroplasty for displaced femoral neck fractures in the elderly. J Arthroplasty. 2004;19(7 suppl 2):73–77.
Bhandari M, Devereaux PJ, Swiontkowski MF, et al. Internal fixation compared with arthroplasty for displaced fractures of the femoral neck: a meta-analysis. J Bone Joint Surg. 2003;85A:1673–1681.
Grecula MJ. Resurfacing arthroplasty in osteonecrosis of the hip. Orthop Clin North Am. 2005;36:231–242.
Healy WL, Iorio R. Total hip arthroplasty: optimal treatment for displaced femoral neck fractures in elderly patients. Clin Orthop Relat Res. 2004;429:43–48.
Lu-Yau GL, Keller RB, Littenberg B, et al. Outcomes after displaced fractures of the femoral neck. A meta-analysis of one-hundred and six published papers. J Bone Joint Surg. 1994;76A:15–25.
Wathne RA, Koval KJ, Aharonoff GB, et al. Modular unipolar versus bipolar prosthesis: a prospective evaluation of functional outcomes after femoral neck fracture. J Orthop Trauma. 1995;9:298–302.