Acetabular cup positioning in revision total hip arthroplasty with Paprosky type III acetabular defects: Martell radiographic analysis

Purpose

This study evaluates acetabular cup position in the setting of revision total hip arthroplasty (THA) with severe acetabular bone defects.

Methods

With a definition of safe zone of abduction (30–50°) and anteversion (5–25°), acetabular cup position was measured by a digital image analysis program for 34 patients with Paprosky type III acetabular bone defects.

Results

There were 24 cups (71 %) for abduction and 26 cups (76 %) for anteversion located in the safe zone. Nineteen cups (56 %) were within the safe zone for both abduction and anteversion. There was no dislocation, however one cup out of the safe zone resulted in early cup failure due to aseptic loosening.

Conclusions

The acetabular cup positioning in patients with Paprosky type III defects was 'optimal' in half of the cases. The prevalence of optimal acetabular cup position was similar to those reported in primary THA, suggesting that the presence of a large acetabular bone defect may not be a significant risk factor for suboptimal acetabular cup positioning in the setting of revision THA.     

Reconstruction of the rotation center of the hip after oblong cups in revision total hip arthroplasty

Background

The preoperative bone defect and the reconstruction of the center of rotation of the hip are critical in acetabular revision surgery. Uncemented oblong cups are employed in order to manage these issues. We analyzed the clinical results and rates of revision of two different uncemented oblong cups, the reconstruction of the center of rotation of the hip, as well as the rate of radiological loosening and possible risk factors.

Materials and methods

Forty-five patients (46 hips) underwent acetabular revision surgery using two different uncemented oblong cups. We assessed the clinical results and the survival rate for revision and aseptic loosening. Intraoperative bone loss was classified according to Paprosky, and acetabular reconstruction was assessed according to Ranawat. The mean follow-up was 7.2 years (range 4–11 years).

Results

There were four re-revisions (three due to aseptic loosening); the survival rate for re-revision due to aseptic loosening was 60.1 % at seven years. The mean distance between the center of the femoral head prosthesis and the approximate center of the femoral head improved from 21.5 to 10.2 mm. Thirteen cups showed radiological loosening; the survival rate for radiological loosening at seven years was 40.54 %. A smaller postoperative horizontal distance was correlated with cup loosening.

Conclusions

Although optimal acetabular reconstruction can be achieved by using oblong uncemented cups in revision hip surgery, the clinical and radiological results are not encouraging. Excessive medialization of the cup may increase the rate of loosening.     

Modular acetabular reconstructive cup in acetabular revision total hip arthroplasty at a minimum ten year follow-up

Purpose

Modular acetabular reconstructive cups have been introduced in an attempt to offer initial rigid fixation by iliac lag screws and ischial pegs, to support bone grafts with a flanged metal socket, and to restore original hip center in acetabular revision. The purpose of this study was to clarify minimum ten year follow-up results of this cup system with morsellised allografts in revision cases.

Methods

We retrospectively investigated 54 acetabular revisions at a mean of 11 years (range, ten to 14 years). The indications were Paprosky’s type 2B (eight hip), 2C (eight hips), 3A (23 hips), 3B (nine hips), and 4 (six hips).

Results

Using aseptic loosening as the endpoints, the survival rate was 89.3 % (95 % CI 81–98). Radiographically, one type 3A hip, three type 3B hips and one type 4 hip showed aseptic loosening while no type 2 hips or no cemented cups showed loosening.

Conclusions

The modular reconstructive cups for acetabular revision showed bone stock restoration and stable implantation.     

5-Jahres-Ergebnisse der zementfreien Allofit®-Press-fit-Pfanne

Background

The Allofit titanium press-fit cup has become the best-selling cementless acetabular implant in Germany, with approximately 30,000 implants sold in 2007. However, only a limited number of scientific publications – mostly from the development centres in Austria – support this success on the market.

Methods

At our institution in 1999–2000, 174 total hip replacements were performed using the Allofit cementless press-fit cup. At a mean follow-up of 5.3 years (range 40–85 months), 154 patients were evaluated clinically and radiographically, representing a follow-up rate of 89%.

Results

The 5-year survival rate was 98.1% (95% CI: 95.8–100%), with revision for any reason as an end point. Three cups were revised (aseptic loosening with one, and two septic complications). The average Harris hip score was 89.1±13.7 in all unrevised patients.

Conclusion

We confirm the excellent survival rates of the Allofit cup as reported by the development centres, supporting the ongoing use of the cup at our institution.     

High incidence of loosening at 5-year follow-up of a cemented metal-on-metal acetabular component in THR

Introduction

High rates of polyethylene wear in metal-on-polyethylene-bearing surfaces correlate with peri-prosthetic osteolysis and early loosening. Hard-bearing surfaces have been used as they may decrease the production of debris and improve survival of the prosthesis. The aim of this study is to ascertain the rate of early loosening of a polyethylene cemented acetabular component with a metal-on-metal (MOM) insert.

Methods

Between 1997 and 1999, 121 total hip replacements in 114 patients were performed at a single centre by two senior surgeons, using the same prosthesis with a MOM hard-bearing surface of 28 mm diameter. At the mean follow-up of 5 years and 6 months (range 5–7 years), nine patients had died and three were lost to follow-up. We reviewed 107 hips (101 patients). The radiographs and case notes of deceased patients were examined. Follow-up was thus 117 out of 121 hips (96%). Results were evaluated clinically with the Merle d’Aubigne classification, and radiographically with analysis of implant migration and radiolucent lines in the Delee and Charnley areas. The survival rate was calculated.

Results

Six patients (5.6%) had revision surgery for aseptic loosening of the cup: one 2 years after the primary operation, two after 4 years, two after 5 years and one after 6 years. The clinical results according to Postel-Merle d’Aubigne gave 85 excellent results (80%), 10 good results (9.4%) and 6 bad results (5.6%). At the latest follow-up, there were no signs of migration, osteolysis or radiolucent lines involving the femoral component. In the acetabular component, there were five cases of radiolucent lines smaller than 1 mm, which were not progressive. In 24 cases, the radiolucent lines progressed over time and there was a probable failure in 18 cases. The survival rate at 5 years is 94.8% taking revision for any cause as the endpoint and 86.9% taking revision or impending failure (as ascertained by radiographic review) of the cup as the endpoint. Numbers of revisions and radiographic failures were significantly higher with the smaller cups (<48 mm diameter) than the larger (p < 0.05).

Conclusions

This series reports a higher rate of failure with a cemented polyethylene cup with a MOM insert than that reported in the scientific literature for metal-on-polyethylene-bearing surface or MOM uncemented cups. Other similar studies found in the literature are discussed. The authors do not recommend use of this cemented polyethylene-Metasul^® acetabular component.     

Primary total hip arthroplasty with a flattened press-fit acetabular component in osteoarthritis and inflammatory arthritis: a prospective study on 416 hips with 6–10 years follow-up

Introduction

A flattened cup was designed to create a more physiological load transfer to the pelvic bone compared to hemispherical cups, and to allow more bone contact compared to low-profile’ spherical cups. To investigate these theoretical advantages and the potential influence of the quality of the acetabular bone, a clinical study was performed in patients with osteoarthritis (OA) and inflammatory arthritis (IA). The aims of the study were (1) to evaluate the fixation of the cup, postoperatively and later when osseous integration should have taken place, (2) to assess perioperative complications such as acetabular fractures and (3) to monitor the polar gap, a potential risk factor for osteolysis.

Patients and methods

A prospective study was performed on all consecutive OA and IA patients with an indication for primary total hip arthroplasty (THA). Three hundred and nine OA patients (340 hips) and 65 IA patients (76 hips) were included. The acetabular component was the flattened press-fit EPF-PLUS^® cup, the femoral component the tapered cementless Zweymueller SL-PLUS^® stem. All revisions and complications were recorded. Clinical and radiographical evaluation was performed on regular basis during 6–10 years.

Results

The incidence of early loosening of the cup was 0 out of 340 in the OA group and 1 out of 76 in the IA group. The incidence of acetabular fractures was 7 out of 340 in the OA group and 3 out of 76 in the IA group. Failure rate for the acetabular component due to aseptic loosening or osteolysis after 6–10 years was 0% in the OA group and 4.8% in the IA group. In all cases available for follow-up the polar gap had disappeared and full osseous integration had taken place in both the groups.

Interpretation

This study shows that the flattened press-fit acetabular component creates adequate initial mechanical stability to allow osseous integration and that the cup can be safely used in both OA and IA patients. However, after 6–10 years, in the IA group failure of the cup due to aseptic loosening occurred once and failure due to osteolysis occurred three times, while these type of failures did not occur in the OA group.     

Early migration characteristics of a 180° porous-coated cup with 1-mm press fit

Introduction

Evaluation of early cup movement is an important diagnostic tool to predict the likelihood of long-term implant loosening and clinical failure. The investigated cementless cup is clinically proven over 10 years, but there is a paucity of information that accurately describes the migration characteristics of this component.

Materials and methods

We retrospectively analysed the clinical outcome and migration behaviour of 60 Pinnacle 100 shells after an average 3.8-year follow-up (range 2.1–5.4 years). For migration measurement, EBRA (Einzel-Bild-Röntgen-Analyse) digital software was applied. Clinical assessment was performed using the HHS, the UCLA score and the SF-36 health survey.

Results

The clinical outcome showed excellent results with a mean HHS of 95.4 (SD 7.1) and mean UCLA of 6.9 (SD 1.3). All implants were radiologically stable within the observation period and none of the cups was at risk for aseptical loosening. EBRA analysis revealed a mean total migration of 1.4 mm (SD 0.9) (95 % CI 1.1–1.6) at 3 years. Eight cups migrated more than 1 mm within the first three postoperative months, thereafter the migration curves flattened down.

Conclusion

Surgeons may expect to find a variable amount of early migration when using the Pinnacle cup. To our knowledge, these are the first results, which show an early “impaction” of a cementless cup, followed by subsequent osseointegration. We believe that an appropriate long-term outcome of the investigated cup is ensured. The data of the present investigation will provide clinicians with useful baseline information with which to compare new cup designs.     

The Exeter method—acetabular impaction grafting with cemented reimplantation

Objective

Restoration of acetabular anatomy and biomechanics at revision hip surgery by replacing deficient acetabular bone through impaction of allograft and/or autograft bone chips.

Indications

Aseptic loosening of the socket due to osteolysis, bone loss from infection, iatrogenic bone loss due to implant removal, and in the primary setting protrusio acetabuli, dysplasia and previous acetabular fracture.

Contraindications

Large segmental peripheral acetabular defects which cannot be contained, the presence of untreated infection, unstable acetabular fractures, previous radiotherapy to the affected hip area.

Surgical technique

Sound exposure of the acetabulum with delineation of the bony defect. Creation of a host environment suitable for bone graft and containment of segmental defects using rim mesh or porous augments. Impaction grafting using layered allograft or autograft bone chips of 0.8–1 cm³, packed using hemispherical impactors, followed by cementing of a polyethylene acetabular component with pressurisation.

Postoperative management

Partial weight bearing 6 weeks, modified depending on level of containment and intra-operative findings.

Results

A successful and reproducible technique with survival up to 87?% at 20 years for aseptic loosening in the revision setting.     

Minimum ten-year results of a 28-mm metal-on-metal bearing in cementless total hip arthroplasty in patients fifty years of age and younger

Purpose

Concerns have been raised in relation to metal-on-metal (MoM) articulations with catastrophic soft-tissue reactions due to metal debris. We reviewed how small head MoM articulations perform in primary uncemented total hip arthroplasty (THA) in young patients at a minimum of ten years.

Methods

We retrospectively evaluated the clinical and radiographic results of the first 100 consecutive primary cementless THAs using the 28-mm Metasul MoM articulation in 91 patients younger than 50 years of age at the time of surgery.

Results

After 13 years, survival for the endpoint revision due to any reason was 90.9 % and 98.9 % for revision due to aseptic implant loosening. The cumulative incidence of MoM related revisions was 1.2 %. Small proximal femoral osteolysis was found in 18 % of hips. No acetabular osteolysis or loosening was detected. Two hips showed signs of femoral neck impingement with severe damage to the neck.

Conclusions

Early in the second decade, MoM-associated complications were rare using the 28-mm Metasul articulation, and aseptic loosening was not a major mode of failure in this cohort of young patients.

Level of evidence

Therapeutic Level IV.     

Modulare Defektrekonstruktion beim Pfannenwechsel mit Abstützschale und metallischen Augmenten

Objective

Restore primary center of rotation and reconstruct extensive bone defects in hip revision surgery with a modular off-label implant combined with antiprotrusion cage and metal augment, thus, achieving improved hip function.

Indications

Large segmental acetabular defects with nonsupportive columns (Paprosky type 3a and 3b) in cup loosening or Girdlestone situation. In case of pelvic discontinuity posterior column-plating is possible.

Contraindications

Persisting hip infection and severe systemic disorders impairing achievement of secondary stability through bony integration of metal augment.

Surgical technique

Posterolateral (if dorsal column plating) or other approach. Remove loose implant and granulation tissue with sufficient exposure of bleeding bone. Size acetabular defect with trial components of augment and appropriate antiprotrusio cage. Fixation of selected metal augment with screws. Fill additional acetabular defects with morsellized bone graft. Open a slot into the ischium to fix the distal flange of the cage. If necessary, bend both flanges according to patient’s anatomy. Enter the ischium with distal flange and gradual impaction of the antiprotrusio ring. Final stabilization of the ring with several screws aiming at the posterior column or the acetabular dome. Inject cement between ring and augment to stabilize the construction and avoid metal wear. Final cement fixation of a polyethylene liner or a dual-mobility cup into the antiprotrusio ring. In pelvic discontinuity with major instability osteosynthesis of the dorsal column can be performed prior to cementation.

Postoperative management

Prophylaxis of periprosthetic infection, DVT and heterotopic ossification. Physical therapy with partial weight bearing (20 kp) for 6 weeks; in discontinuity initial wheel chair mobilization.

Results

Since 2008, 72 off-label implantations of a combined antiprotrusio cage and a Trabecular Metal? Augment were performed. A total of 44 patients (46 operations) were investigated at 38.8 (36–51) months postoperatively. In all, 36 patients had a bone defect according to Paprosky type 3a/b and in 3/4 patients with pelvic discontinuity additional osteosynthesis was performed. The WOMAC score increased from 39.8 (8.7–75) points preoperatively to 57.9 (16.7–97.9) points at follow-up. Migration or failure of implant components was not observed. In 11?% of dislocations and 11?% periprosthetic infections surgical revision was necessary.     

Results at a minimum of 10 years of follow-up for AMS and PerFix HA-coated cementless total hip arthroplasty: impact of cross-linked polyethylene on implant longevity

Purpose

The purpose of this study was to report results at a minimum of 10 years for hydroxyapatite (HA) coating on the titanium arc-sprayed cementless total hip arthroplasty (THA) and to evaluate the impact of cross-linked polyethylene (XLPE) on implant longevity.

Methods

A total of 131 consecutive primary THAs in 123 patients using an AMS acetabular cup and a PerFix HA stem were retrospectively reviewed. Conventional PE was used for 62 hips (CPE group) and cross-linked PE for 69 hips (XLPE group), with mean follow-up periods of 13 and 11.5 years, respectively. These patients were reviewed using the Japanese Orthopaedic Association (JOA) Hip Score and evaluated in terms of PE wear, osteolysis, and implant survival.

Results

The JOA score improved from 42.6 to 83.9 points at the final follow-up. The mean wear rate of 0.12 mm/year in the CPE group was significantly greater than that of XLPE at 0.007 mm/year. In the CPE group, ten (16.1 %) and two (3.2 %) hips, respectively, underwent PE exchange due to severe wear and acetabular revision due to loosening associated with osteolysis. Three patients had revision in the XLPE group: one cup for aseptic loosening, one PE for recurrent dislocation, and one stem for neck fracture. No evident osteolysis was seen in the XLPE group. Kaplan–Meier survivorship with any revision as the end point shows that the 12-year survival rate was 97.7 % for cups, 93.8 % for PE liners, and 99.2 % for stems. Multivariate analysis revealed that the use of XLPE significantly reduced the risk of revision, with the odds ratio (OR) of 4.3.

Conclusions

AMS and PerFix HA components in this series show excellent implant fixation; however, high rates of PE wear and subsequent osteolysis were limiting factors in long-term success. Low wear rates with XLPE suggest improved implant longevity.     

Excessive polyethylene wear and acetabular bone defects from standard use of a hooded acetabular insert in total hip arthroplasty

Purpose

In total hip arthroplasty (THA) the use of a polyethylene (PE) insert with a hooded rim can be considered to reduce dislocation risks. This benefit has to be balanced against the potential introduction of impingement of the femoral component on this rim. We present a case series of early acetabular revisions for excessive PE wear and acetabular bone defects from overuse of such a hooded rim insert.

Material and methods

Twenty-eight patients with 34 consecutive early acetabular revisions were evaluated on failure mechanism. One type of implant was used in all cases. Standard pelvic radiographs and pre-operative CT scans were used to quantify PE wear, implant positioning and acetabular bone defects.

Results

An acetabular revision with impaction grafting was performed in all cases with a mean cup survival of ten years (range 1.3–19.3). No concurrent stem revisions were necessary. Overall implant positioning was adequate with a mean cup inclination of 45° (range 39–57) and anteversion of 25° (range eight to 45). The mean PE wear was 0.24 mm/year (range 0.00–1.17). The mean acetabular bone defect on pelvic CT scans was calculated as 352 mm² (range zero to 1107) and 369 mm² (range zero to 1300) in the coronal and transversal planes, respectively. A hooded acetabular insert was retrieved in all cases and profound PE wear, typically from the posterior hooded rim, was encountered.

Conclusion

The use of hooded acetabular inserts may be considered to improve implant stability intra-operatively. This case series clearly presents that together with these devices, component impingement with concordant complications such as accelerated PE wear may be introduced. Standard use of these stabilizing inserts should thus be avoided.     

A cementless hip system with a new surface for osseous integration

Purpose

The failure of total hip systems caused by wear-particle-induced loosening has focused interest on factors potentially affecting wear rate. Remnants of the blasting material were reported on grit-blasted surfaces for cementless fixation. These particles are believed to cause third-body wear and implant loosening. The purpose of this study was to evaluate the early clinical and radiological outcomes of a cementless hip system with a new, contamination-free, roughened surface with regard to prosthesis-related failures.

Methods

Between May 2004 and March 2009, 202 consecutive primary total hip arthroplasties (THAs) (192 patients with a mean age of 62.6 years) were performed using a cementless stem (Hipstar®) and a hemispherical acetabular cup (Trident®).

Results

At a minimum follow-up of two years, five revisions (2.5 %) due to aseptic loosening of the stem and three (1.5 %) of the cup were necessary. The cumulative rate of prostheses survival, counting revision of both components and with aseptic failure as end point, was 92.9 % at 8.8 years. Radiolucent lines up to three millimetres were evaluated in the proximal part of the femur in 61 % of cases.

Conclusions

Although the incidence of radiolucent lines was decreased, the revision rate was considerably increased compared to other uncemented hip implants with grit-blasted surfaces in the short- to mid-term follow-up of our study. Subsequent studies are needed to confirm whether these changes in implant material and surface affect the radiological and clinical outcome in the long term.     

Medial placement of the acetabular component in an alumina-on-alumina total hip arthroplasty: a comparative study with propensity score matching

Purpose

In an alumina-on-alumina total hip arthroplasty (THA), recommended with a small inclination angle <45°, the acetabular component (cup) may be positioned more medially to be covered almost completely by host bone. The purpose of this study was to identify the correlating factors and to evaluate the outcomes of medial placement of the cup in patients with alumina-on-alumina THAs.

Methods

Using the propensity score matching with age, gender, body mass index, initial diagnosis, and the length of follow-up as variables, 38 hips with a medialized cup and 38 hips with a non-medialized one were identified from 389 hips in 347 who patients underwent primary alumina-on-alumina THA and followed up for more than 7 years. Clinical and radiological outcomes were compared between the two groups.

Results

Preoperative acetabular medial wall thickness and the cup inclination angle were significantly smaller in the medialization group compared to the non-medialization group. Center edge angle, cup size, and coverage by host bone were not significantly different between the two groups. The hip center of rotation was significantly medialized in the medialization group. The Harris hip scores were not significantly different between the two groups. No component loosening or osteolysis was observed and no revision was required in either groups.

Conclusions

Thin acetabular medial wall and a small inclination angle of the cup were the correlating factors of medial placement of the cup in patients who underwent an alumina-on-alumina THA. Medial placement did not lead to differences in the clinical or radiological outcomes.     

Abstützschalen in der Revisionsendoprothetik der Hüfte

Background

Acetabular revision in total hip arthroplasty (THA), especially for loose or migrated cup components with collateral bone loss, remains a great surgical challenge. The aim should always be a functionally favorable reconstruction of the rotation center with sufficient load capacity of the acetabulum. Commonly used implants in Europe are the Mueller ring, the Ganz ring, and the Burch–Schneider cage.

Patients and Methods

We report our results of 298 patients (298 hips) with a median follow-up period of 4 (range 0–17) years in a retrospective series.

Results

Follow-up data were available in 224 cases (75%). A radiographic examination was performed in 176 (59%) patients. Another 54 patients (18%) had died in the follow-up period, while another three patients (1%) were lost to follow-up. Eighteen patients (16%) underwent re-revision, in nine cases for aseptic loosening and in the remaining nine cases for infection. In seven additional cases (2%), radiological and clinical failure was found during follow-up. The overall survival rate was 94% at 5 years and 89% at 8 years.

Conclusion

Revision THA using acetabular reinforcement rings results in acceptable midterm results. However, septic complications and lysis of the bone graft with consecutive failure of the reinforcement ring remain problematic.     

Systematic review on outcomes of acetabular revisions with highly-porous metals

Purpose

The purpose of this study was to systematically review the literature and report the clinical and radiographic outcomes of highly-porous acetabular cups in revision settings.

Method

A literature search of four electronic databases of EMBASE, CINAHL-plus, PubMed, and SCOPUS yielded 25 studies reporting the outcomes of 2,083 revision procedures with highly-porous acetabular components. There was lack of high quality evidence (level I and level II studies) and only two studies with level III evidence, while the remainder were all level IV studies. In addition, a majority of the studies had small sample sizes and had short to mid-term follow-up. The mean age of the patients was 65 years (range, 58–72 years) and the mean follow-up was 3.6 years (range, two to six years). Outcomes evaluated were aseptic survivorship, Harris hip scores, migration rates, incidence of peri-acetabular radiolucencies and radiographic restoration of the hip centre.

Results

The mean aseptic survivorship was 97.2 % (range, 80–100 %). The Harris hip scores improved from a mean pre-operative score of 42 points, (range, 29–75 points), to a mean postoperative score of 79 points (range, 69–94 points). The mean incidence of cup migration and prevalence of peri-acetabular radiolucencies was 2.4 % (range, 0–8.8 %) and 4.6 % (range, 0–19 %), respectively, at final follow-up. The vertical hip centre-of-rotation was restored significantly from a mean of 39.2 mm (range, 27.6–50 mm) pre-operatively, to a mean of 24.1 mm (range, 7.4–47 mm), postoperatively.

Conclusion

The short-term clinical and radiographic results of highly-porous metals in revision hip arthroplasty are excellent with a low rate of loosening in the presence of both major and minor bone loss.     

Biologisch azetabuläre Defektrekonstruktion beim Hüftendoprothesenwechsel mittels „Impaction Grafting“ und azetabulärem Rekonstruktionsring

Objective

Management of acetabular bone defects Paprosky types IIa and IIb in revision hip arthroplasty by rebuilding the bone stock using impaction bone grafting, primary stable reconstruction with an acetabular reconstruction ring, and restoring the hip center of rotation to its anatomical position.

Indications

Acetabular segmental or combined structural defects in the superior acetabular dome with superior/lateral hip center migration with intact anterior and posterior columns (Paprosky types IIa, IIb).

Contraindications

Acute or chronic infections, severe acetabular bone defects preventing adequate anchorage of the prosthesis—particularly destruction of the posterior column.

Surgical technique

Modified transgluteal, lateral approach to the hip joint. Removal of the loose acetabular component. Complete circumferential exposure of the acetabular rim, while maintaining mechanical stability of the remaining bone. Preparation of the homologous spongiosa chips and reconstruction of the acetabular defect in impaction grafting technique. Implantation of the acetabular reconstruction ring and primary stable fixation with cancellous screws in the acetabular dome. Cemented fixation of a polyethylene inlay.

Postoperative management

Mobilization on 2 underarm crutches from postoperative day 1. Partial weight bearing with 20 kg for 6 weeks postoperatively. If plain radiographs show unchanged seating of the prosthesis after 6 weeks, loading can be increased by 10 kg/week until full weight bearing is achieved; thrombosis prophylaxis is continued throughout. Limitation of hip flexion to 90° during the first 6 weeks, and no adduction and forced external rotation to avoid dislocation. Avoidance of sports involving jumping and axial impact loading for 12 months. Radiologic checkups after 3, 6, and 12 months and, thereafter, every 2 years.

Results

Analysis between 2008 and 2011 involved 22 consecutive patients with a total of 23 prostheses; the mean follow-up was 38?±?11 months. Compared to the preoperative evaluation, follow-up yielded a significant improvement in the average Harris Hip Score (82.2?±?8.7 vs. 44.7?±?10.7) and the Merle d’Aubigné Score (14.6?±?1.9 vs. 7.5?±?1.3). Radiological solid osseointegration of the cup was observed in 21 cases; partial radiolucent lines were seen in 2 cases (9?%) in the zones I–III delineated by DeLee and Charnley. In 21 cases (91?%) radiographs confirmed no measurable migration or displacement of the acetabular component and the bone graft was determined to be incorporated on the basis of osseous consolidation within the grafted area in 20 cases (87?%). During follow-up 3 prosthesis (13?%) required revision.