Bone-preserving total hip arthroplasty in avascular ... - Springer Link

International Orthopaedics https://doi.org/10.1007/s00264-018-3896-9

ORIGINAL PAPER

Bone-preserving total hip arthroplasty in avascular necrosis of the hip—a matched-pairs analysis David Merschin 1 & Richard Häne 2 & Mersedeh Tohidnezhad 3 & Thomas Pufe 3 & Wolf Drescher 2 Received: 26 February 2018 / Accepted: 13 March 2018 # SICOT aisbl 2018

Abstract Purpose Short-stem hip arthroplasty has the potential advantage of femoral bone stock preservation, especially in view of the expected revisions in the often relatively young patients. Despite short-stem hip prosthesis are increasingly used for total hip arthroplasty, there are no sufficient mid- and long-term results especially for patients with avascular femoral head osteonecrosis. The present study investigates mid-term functional results as well as the revision rate following implantation of a short-stem prosthesis. Methods In the period 06/2005 until 12/2013, a total of 351 short-stem hip prostheses were implanted. The study included 331 complete data sets. A retrospective analysis was performed using the Oxford Hip Score. All revisions were registered. Results In a total of 331 prostheses, the Oxford Hip Score was Bexcellent^ in 66.2%, Bgood^ in 12.7%, Bfair^ in 13.0%, and Bpoor^ in 8.2% with a mean follow-up of 57.4 months (SD ± 29.8; range 24–115). In 26 cases, aseptic osteonecrosis of the hip was the indication (7.9%). The Oxford Hip Score was Bexcellent^ in 66.7%, Bgood^ in 0.0%, Bfair^ in 20.8%, and Bpoor" in 12.5%. The cumulated five year survival rate was 96.7%. Conclusion In mid-term observation, the Metha® short-stem prosthesis shows no disadvantage in functional outcome and in survival time compared to a standard hip stem. Providing a correct indication, the Metha® short stem is a valuable option in total hip arthroplasty for younger patients with avascular osteonecrosis of the femoral head. Evaluation has shown no significant differences between aseptic osteonecrosis and other indications. Keywords Short-stem hip arthroplasty . Avascular necrosis . Hip

Introduction Idiopathic femoral head necrosis usually affects patients in the third to fifth decade of life and men are affected about five

* David Merschin [email protected] Richard Häne [email protected] Thomas Pufe [email protected] 1

Clinic for Trauma Surgery and Orthopaedics, BG Klinikum Unfallkrankenhaus Berlin, Warener Straße 7, Berlin, Germany

2

Department of Orthopaedic Surgery of the Lower Limb and Arthroplasty, Hospital Rummelsberg, Rummelsberg 71,, Schwarzenbruck, Germany

3

Institut für Anatomie und Zellbiologie, Uniklinik RWTH Aachen, Pauwelsstraße 30, 52074 Aachen, Germany

times as often as women. The chances of successful jointpreserving surgery, such as core decompression, are very uncertain from the necrosis stage > ARCO III (Association Research Circulation Osseous) and are only successful in about one in four patients. If a loss of sphericity of the femoral head has occurred, secondary osteoarthrosis subsequently occurs, leaving only the possibility of total hip replacement (THR) for the maintenance of a good hip joint function [1]. Total hip replacement has proven to be an established procedure with good long-term results. Young patients are a growing patient group for THR [2]. Due to the young age, these patients—especially those with AVN—sometimes need multiple revisions. In 2011, 26% of all total hip replacements were performed in patients under 65 years of age [2]. There is also a lack of consensus about the most appropriate method of arthroplasty in patients with osteonecrosis of the femoral head [3]. In choosing the implant, consideration must be given to the extent of the necrosis area as well as the usually young age of the patient. Furthermore, the aetiology of femoral head necrosis should also be taken into consideration, as this significantly influences the

International Orthopaedics (SICOT)

longevity of the endoprosthesis and the complication rate. The reduction of biomechanical and biological bone quality can lead to early implant failure, which is why the endurance after posttraumatic and idiopathic AVN is significantly better than, for example, in the case of alcohol or steroid-induced AVN [4]. Within the scope of prostheses development, various short stems have been established on the market. The design aims at a bone-preserving implantation and can be particularly advantageous for young patients. Furthermore, these implants facilitate a minimally invasive approach and allow for faster rehabilitation [5, 6]. Fifteen percent to 20% of hip arthroplasties in Germany use short stems [7]. To date, however, only a few studies with larger numbers of cases are available [8, 9]. The implant design of the Metha® stem prosthesis (B. Braun Aesculap, Tuttlingen, Germany) (Figs. 1 and 2) has been increasingly used since its development—the relative portion since product launch has risen by 20% [10]. The prosthesis follows the biomechanical theory of a proximal force transmission into the metaphysis as well as in the region of the calcar [9]. This requires a closed bony femoral neck ring as well as a high bone quality. After bony integration, the tip does not transfer significantly higher forces to the diaphysis [11]. The purpose of the present retrospective study was to encompass the functional outcomes and the endurance of the Metha® short-term prosthesis in a matched-pairs analysis in mid-term follow-up.

Fig. 1 Antero-posterior radiograph of a right hip following Metha-stem implantation

Fig. 2 Intra- and postoperative radiological control

Materials and methods The study included patients who were implanted a Metha® short-stem prosthesis at Rummelsberg hospital from 06/2005 to 12/2013. Exclusion criteria were patients aged below 18, loss of patient contact, incomplete data collection, and lack of consent to study or data collection. Patients with a follow-up of less than 24 months were not included in the study. Pre-operative planning of the prosthesis was performed using semi-transparent paper and planning templates until 06/2012 and then using digital planning software (mediCAD® lower limb version 3.0, Hectec GmbH, Landshut, Germany). The Metha® short stem (B. Braun Melsungen AG, Tuttlingen, Germany) is made of titanium alloy (ISOTAN®F Ti-6Al-4V) and additionally coated in the shaft area with a 20-μm thick calcium phosphate layer (Plasmapore® μ-CaP). This implant is available with tapers in 120°, 130°, and 135° CCD angles. The indication for total joint replacement was primary hip arthritis and avascular necrosis of the hip. Implantation was performed via transgluteal approach under general anesthesia and single-shot antibiosis. The transgluteal approach was performed in supine position. After a dorsally arcuated incision over the greater trochanter region, we divided the Musculus gluteus medius longitudinally at a line dividing the width of the greater trochanter ventrodorsally. The joint capsule was split and left in place. The femoral neck was osteotomized and the femoral head removed. After reaming the acetabulum, components were implanted. After repositioning the leg in external rotation and adduction, the stem was implanted. A reconstruction of the joint capsule was also part of the procedure. The muscles were reattached to the trochanter bone stock. The interventions were carried out by a total of three senior surgeons of our clinic for orthopaedic surgery of the lower extremities and arthroplasty. All


surgeons are specialists in Orthopaedics and Trauma Surgery with many years of arthroplasty experience. Intra- and post-operative radiological control was performed in two planes (a.p. and Lauenstein-position) (Figs. 1 and 2). For all patients, an after-treatment scheme with the earliest possible remobilization was performed under partial weight bearing with 15 kg for six weeks using crutches. After reaching independent walking ability, an inpatient rehabilitation treatment was carried out directly. Retrospective data collection was performed using a validated, modified Oxford Hip Score (OHS). OHS is a diseasespecific questionnaire with 12 items [12, 13]. In addition, we recorded the number and reasons for revision surgery. The guidelines of the Helsinki Declaration (October 2013) were followed in accordance with national law. Each of the patients, or the legal guardian, agreed to participate in the study. A total of 331 complete data sets were collected (Fig. 3). The indication was based on clinical symptoms and conventional x-ray images in two planes (pelvic overview and hip joint according to Lauenstein). Subsequently, the AVN

patients were selected. This step was then followed by a matched-pairs analysis. Data were processed using GraphPadPrism (GraphPad Inc., version 3.0, La Jolla, CA, USA). A statistical significance level of p < 0.05 was assumed. We performed a Wilcoxon Matchedpairs signed ranked test to compare results for primary arthritis and AVN. All AVN-hip arthroplasties were matched 1:1 to primary osteoarthritis hip arthroplasties of the same period, according to patient age, sex, localization, and duration of follow-up. The study has been approved by the Ethic Committee of the Friedrich-Alexander-Universität Erlangen-Nürnberg (Application No.: 330_15 B) and has been performed in accordance with the ethical standards in the 1964 Declaration of Helsinki. Furthermore, the study has been performed in accordance with the regulations of the US Health Insurance Portability and Accountability Act (HIPAA).

Results Demographic data In the period from 06/2005 to 12/2013, 331 hips were treated. From 06/2005 to 10/2008, 72 patients received a modular metha® short stem. Five of all patients were not available for follow-up by mail or by phone. Forty-two patients were excluded because of a follow-up less than 24 months. Twenty one patients were excluded because of missing data. Three hundred thirty-one complete sets of data were collected (Fig. 3). Consequently, a follow-up rate of 82.96% was obtained. The data analysis showed a gender distribution of 22 men (51.06%) and 4 women (48.94%) in each group, a side distribution of 13 left-sided (52.0%) and 13 right-sided (48.0%) prostheses in each group. The age distribution showed an average age of 52.7 years (SD ± 7.31 years, range 36–69) in the AVN group and 56.5 years in the primary osteoarthritis group (SD ± 5.6 years, range 49–64). There was no significant difference between groups (p = 0.1849). The mean follow-up period was 5.5 years (65.9 months; SD ± 25.5; range 27–108).

OHS in AVN group The evaluation of the elevated Oxford Hip Score showed Bexcellent^ in 20 cases (OHS < 19: 76.9%), Bgood^ in zero cases (OHS = 19–26: 0.0%), BFair^ in three cases (OHS = 27–33: 11.5%), and Bpoor^ in three cases (OHS > 33: 11.54%) (Fig. 4).

OHS in primary osteoarthritis group

Fig. 3 Data sets

Evaluation of the elevated Oxford Hip Score showed Bexcellent^ in 19 cases (OHS < 19: 73.1%), Bgood^ in six cases (OHS = 19–26: 23.1%), BFair^ in one case (OHS = 27–33:


May 2009 by a stem change. At the time of primary surgery, the patient was 48 years old, 175-cm tall and 76 kg (BMI 24.8 kg/m2). In addition to this, another adapter failure occurred (in case of secondary osteoarthritis due to hip dysplasia). However, this patient did not participate in the study.

Discussion Fig. 4 The evaluation of the elevated Oxford Hip Score

3.9%), and Bpoor^ in zero cases (OHS> 33: 0.0%) (Fig. 4, Table 1). There is no significant difference between both groups according to the OHS (p = 0.8221) (Fig. 5).

Revisions A total of one surgical revision was reported (1.9%)—caused by dislocation (19 months post-operatively). Furthermore, one adapter failure (1.9%) occurred 30 months post-operatively in the investigated primary osteoarthritis group. Primary implantation was performed in October 2006 (taper adapter 130°, 7.5° anteversion). The revision was finally carried out in Table 1 Evaluation of the elevated Oxford Hip Score

Avascular femoral head necrosis usually affects patients in the third to fifth decade of life. Men are affected much more often than women (5:1). The chances of successful joint-preserving surgery, such as retrograde drilling for decompression, are very uncertain for the necrosis stage > ARCO III. This technique is successful in about 25% of all patients. But if a loss of the femoral head sphericity has occurred, secondary osteoarthrosis subsequently occurs [1]. Bone-preserving arthroplasty systems are required since, on the one hand, patients who require hip arthroplasty become younger in general, and on the other hand, certain diagnoses like hip dysplasia, impingement, and AVN of the femoral head typically lead to early secondary arthritis of the hip. This led to the development of bone-preserving stems [14–19]. Current reviews recommend further studies for mid- and long-term results of short-stem implantation [20]. Therefore, the aim of this study was to compare mid-term outcomes in patients

AVN

Primary osteoarthritis

Number of hips Gender (male/female

26 22/4

26 22/4

Side (left/right) Age (range, SD) Follow-up (range, SD) OHS (range, SD) Excellent (%) Good (%) Fair (%) Poor (%) Revisions (%) - Aseptic loosening

13:13 52.69 (36–69; ± 7.31) 65.88 (27–108; ± 25.49) 18 (12–46; ± 10.35) 20 (76.92) 0 (0.00) 3 (11.54) 3 (11.54) 1 (3.85) 0 (0.0)

13:13 56.46 (49–64; ± 5.56) 65.88 (27–108; ± 25.49) 16 (12–32; ± 5.65) 19 (73.08) 6 (34.62) 1 (3.85) 0 (0.00) 0 (0.0) 0 (0.0)

- Material failure - Heterotopic ossification - Infection - Hematoma/soft tissue - Instability - Squeaking - Femoral perforation - Femoral fracture

0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 (3.85) 0 (0.0) 0 (0.0) 0 (0.0)

1 (3.85) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)


Fig. 5 Significant difference between both groups according to the OHS

undergoing implantation of a short stem in femoral head necrosis compared to primary osteoarthrosis. The success of hip arthroplasty in osteonecrosis of the femoral head has been widely documented in recent years for both cemented and cementless implantation [21–25]. However, there are also reports of a lower total hip replacement time in patients with femoral head necrosis compared to those with primary arthritis [26–30]. On a global scale, the Metha® short-stem prosthesis demonstrated convincing clinical results in the observed patient group of 331 patients, which can withstand a comparison with conventional standard prostheses. We also see no inferior functional outcomes compared to a standard prosthesis [31, 32] (Figs. 4 and 5). In case of the Metha® stem, it is a relatively new implant, lacking sufficient mid- and long-term results. Unconditionally, it is necessary to evaluate a new method as well as a new implant with regard to the success and the results, in order to be able to show success or failure. Our study has some limitations: the retrospective study design as well as the missing separate X-ray examination beyond the standard controls. Another limitation is the relatively small sample size, which can be explained by the character of a single-centre study. Furthermore—with respect to a retrospective design—treatment was not randomized. Therefore, we performed a matched-pairs analysis. We have not examined patient satisfaction according to quality of life (e.g., SF36).

The data were evaluated using the Harris Hip Score as well as the Western Ontario and McMaster score. Both groups included 50 patients. In both scores, no statistical difference was observed for comparable demographic data and satisfactory results after five years [33]. At this point, it is noteable that in case of a comparison, the comparatively low age profile of the patients, which is associated with a higher physical activity and thus load on the implant, has to be considered [34, 35]. Morrey et al. have shown a seven year survival rate of 98% in a young patient group. It should be mentioned at this point that the anchoring principle of the Metha® stem is comparable to that of the Mayo stem [16]. In a ten year follow-up case-control study, Ancelin et al. have shown that survival was similar in both groups (AVN: 92.5% vs. osteoarthritis: 95.3%) [36]. Radl et al. reported a stem revision rate of 15.4% due to aseptic loosening after an average of 6.4 years implanted in advanced femoral head necrosis [28]. Brinker et al. also reported a reduced durability and increased revision rate in 64 patients with femoral head necrosis after implantation of a cementless total hip replacement [37]. An explanation for the increased loosening rates could be found in the method described by Arlot et al. They also found bone metabolic disorder in iliac crest biopsies in patients with osteonecrosis of the femoral head [38]. In the biopsy material, a reduced calcification rate as a consequence of a reduced appositional osteoblast activity, which led to a reduction of trabecular bone mass, was detected as dominant disorder. For cementless arthroplasty, these results could be expected to compromise secondary stability because repair of microfractures resulting from rasping the implant bed and osseous implant integration require appositional osteoblast activity [39]. This hypothetical adverse effect could be more pronounced in short stems because of the much smaller implant surface. Tingart et al. found in their study of trabecular microarchitecture a bone volume reduction as well as changes of bone structure in femoral head necrosis compared to results in coxarthrosis. The authors conclude that epiphyseal and metaphyseal changes in bone remodeling and bone matrix in femoral head necrosis may explain higher loosening rates of hip endoprostheses reported in the literature [40]. A possible conclusion from these results is that in case of femoral head necrosis, poorer results could be expected in short stems because of reduced osteointergration. This was part of motivation to investigate the durability of this shortstem prosthesis in addition to the clinical results.

Younger patients with femoral head necrosis Durability Shin et al. compared the Metha® stem with a standard straight stem component (BiContact, Aesculap, Tuttlingen, Germany).

Secondary osteoarthritis to osteonecrosis of the femoral head occurs in patients between the ages of 30–60 years: in summary, younger patients are affected [41]. The longevity of hip arthroplasties has lead to an increased acceptance of implantation


in younger and more active patients. Nevertheless, a lack of consensus about the most eligible arthroplasty method in younger patients exists but some satisfying studies reporting short stems in younger patients are present [42, 43]. In 2017, Capone et al. have illustrated 30 patients (37 joint replacements; NANOS®, Smith and Nephew, Marl, Germany) with a mean age of 51.5 years and a mean follow-up of 5.6 years. Clinical results have shown a significant increase in Harris Hip Score (pre-operative: 53 vs. post-operative: 90 points; p < 0,001) [25]. These results are comparable to the majority of reports in literature of recent years [8, 44, 45]. Swarup et al. published a study about AVN patients which are 35 or younger. They were able to include 135 patients (204 hip replacements). Mean follow-up was 14 years. They reported an implant survival of 86% for 10 years. They concluded a good implant survival for young AVN patients [46]. Floerkemeier denominates short-stem hip arthroplasty as an encouraging method for femoral head osteonecrosis patients. In a study with 74 hips in 64 patients with femoral head osteonecrosis, the Harris Hip Score increases from 37.7 preoperatively to 89.3 points post-operatively (mean follow-up 34 months) [8]. Braun et al. reported a Harris Hip Score of 95 points in a cohort of 48 patients with good osseointegration of Metha short stem in all patients [47]. In a cohort of 12 patients with femoral head osteonecrosis, short-stem implantation has not shown an increased migration or tilt [44]. With a mean follow-up of 2 years, Suksathien et al. analyzed 120 Metha stem implantations after osteonecrosis of the femoral head. Harris Hip Score improved from 43.9 preoperatively to 97.7 post-operatively. They reported no revisions but seven intra-operative complications (six fractures (5%) and one distal stem perforation (0.8%)) [45]. Budde et al. compared a hip dysplasia group to a control group (primary osteoarthritis). With a mean follow-up of 2.9 years, they reported an increased Harris Hip Score in both groups (p < 0.0001) and concluded that the Metha short stem leads to good results in hip dysplasia as well [48].

Complications and revisions The study by Lewinski et al. showed a revision rate of 2.3% (n = 45) for a large number of patients (n = 1.953) from 2005 to 2013. Twelve of these patients received revision due to mechanical failure of the prosthesis neck. Nineteen patients had aseptic loosening (0.8%). In the remaining cases, five periprosthetic fractures were present (0.3%) [10]. Overall, a low rate of aseptic loosening was observed in our study (1.5%, n = 5). These occurred in four out of five cases in the first postoperative year [32]. Hungerford et al. showed a revision rate of 8.9% after 8.5 years in patients with osteonecrosis of the femoral head [24]. Thorey et al. were able to show a revision rate of only 1.8% (n = 3), but in a study with only 151 patients. One case was an early infection and two cases of

sintering of the stem as a result of an undersized stem. In addition, two cases of heterotopic ossification were reported. No statement is made about a required revision. The durability of the prosthesis was indicated in a Kaplan-Meier curve with 98.0% (mean follow-up 5.8 years) [9]. In 2015, Shin et al. have published a case-control study with 50 patients per group with a mean follow-up of 56 months. It did not show any statistical differences between patients who received a Metha® stem and those who received a conventional stem. The rate of complications in this study was as follows for the Metha® stem: sintering, periprosthetic fracture, leg length difference, heterotopic ossifications, and dislocation, respectively 2.0% [33]. No adapter failure occurred in our study population. In the period from 2005 to 2013, 1953 Metha® stems were implanted in the Orthopedic Clinic of the Hannover Medical School. This corresponds to a revision rate of 6.1% caused by taper failures. The proportion of patients with a BMI of > 35 was 30% [49]. In summary, mid-term results suggest that the Metha® short stem may be a bone-preserving solution for younger patients needing THR. For long-term evaluation, further studies exceeding ten years are necessary to approve this presupposition. In summary, in case of idiopathic AVN, the use of femoral neck-preserving implants leads to reliable results—also compared to those in primary osteoarthritis. The use of this prosthesis in femoral head osteonecrosis, which is associated with a general reduction in bone metabolism, for example, as a result of nephropathy, corticoid therapy, or as a result of immunosuppressive treatments, is not recommended in literature. In case of a co-existing general reduction of bone quality of the proximal femur, the use of these implants should be critically weighed on the dependency of hip geometry restoration on one hand and on the expected life of the patient on the other hand. The few previous reports on the use of these implants to treat AVN are at least promising [8, 11, 36, 44, 46]. Funding information This study was co-financed by the Rudolf und Irmgard Kleinknecht-Foundation, Rottendorfer Str. 3, 97072 Würzburg, Germany.

Compliance with ethical standards The study has been approved by the Ethic Committee of the FriedrichAlexander-Universität Erlangen-Nürnberg (Application No.: 330_15 B) and has been performed in accordance with the ethical standards in the 1964 Declaration of Helsinki. Furthermore, the study has been performed in accordance with the regulations of the US Health Insurance Portability and Accountability Act (HIPAA). Conflict of interest David Merschin, Richard Häne, Thomas Pufe, and Mersedeh Tohidnezhad do not have any conflict of interest. Wolf Drescher works as a consultant for Zimmer Biomet and as an instructor for B. Braun Aesculap.


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