Acetabular revisions using a cementless oblong cup: five to ten year results

Technical note: acetabular augmentation with customisable cementless all-polyethylene insert

Acetabular augmentation is a challenge for complex primary and revision hip surgery. Several methods exist to recreate a supportive, hemispherical acetabulum where a defect exists, however, these can be complex, expensive, time consuming, and limited by available size and shape. We present a simple, inexpensive, quick and customisable method of acetabular augmentation using cementless polyethylene with titanium coating. The first case is presented with follow-up up to 8 years.

Trabecular titanium cups in acetabular revision arthroplasty: analysis of 10-year survivorship, restoration of center of rotation and osteointegration

AIMS

In case of severe bone loss, acetabular revision can be challenged using extra porous pure trabecular titanium (TT) revision cups designed to ensure enhanced iliac and ischiatic purchase. Aim of the study is to report on the clinical and radiological results of a TT acetabular component, evaluating functional outcome, restoration of the hip center of rotation and osteointegration.

METHODS

85 patients, who underwent acetabular revision with a TT revision cup system between October 2009 and December 2018, were included in a retrospective study. Clinical outcome were assessed with Harris Hip Score (HHS). The hip rotation center was measured using the Pierchon method on the AP pelvis film. Loosening of the cup was determined according to the Kosashvili modification of Gill's criteria. Kaplan- Meier survivorship curve was performed. Results The mean follow-up was 6.12 years. The average HHS improved from 54.7 points to 89.7 points (p < 0.05). Two acetabular components (2.3%) were re-revised after a mean of 5.6 years, for aseptic loosening and for infection, with a progressive radiolucency and a > 5 mm vertical migration, respectively. The radiographic evaluation of the position of the hip rotation center revealed a statistically significant difference (p < 0.05) between the pre- and post-operative values. The hip rotation center was correctly restored within 5% of the reference Pierchon values in a percentage of 85.4% relative to horizontal parameters and within 8% in a percentage of 66.7% relative to vertical parameters. 5-year and 10-year survivorships were, respectively, 100% and 88%.

CONCLUSIONS

In case of severe bone loss, TT revision cup system allows for good restoration of center of rotation and osteointegration showing good 10-year survival rate.

Minimum 10 years clinical and radiological outcomes of acetabular revisions of total hip arthroplasties with tricalcium phosphate/hydroxyapatite bone graft substitute

BACKGROUND

Aseptic loosening is the most frequent indication for revision of total hip arthroplasty. Revision arthroplasty of acetabular component is a challenge for every surgeon because they have to simultaneously deal with the reconstruction of bone defects, adequate implant geometry and stable fixation. Allografts are the most frequently used materials in reconstruction of bone loss during revision surgeries. Because of an increasing number of revision hip arthroplasties and poor availability of allografts, we decided to use bone graft substitutes in acetabular revisions.

METHODS

Between September 2005 and January 2010, 44 revision arthroplasties in 43 patients were performed with the use of bone graft substitutes for acetabular defect reconstruction in revision of total hip arthroplasty. Acetabular bone defects were classified according to Paprosky. Seventeen hips were classified as IIA, 3 hips IIB, 3 hips IIC, 10 hips IIIA and 11 hips IIIB. Acetabular bone defects were reconstructed with tricalcium phosphate/hydroxyapatite bone graft substitute - BoneSave. Clinical and radiological examination was performed after 3 months, 1 year and then annually. Harris hip score was used for clinical evaluation. Survival analysis was performed with Kaplan-Meier method with aseptic loosening as the definition of endpoint.

RESULTS

The average follow-up period is 12 (range from 10 to 15) years. During the follow-up, three patients died after 24 months because of causes not related to surgery. None of the patients was lost to follow-up. The evaluation of clinical results revealed an increase in pre-operative HHS from average 38.3 (range 25 to 55) points to average 86.3 (range 45 to 95) points at the most recent follow-up. Radiographic evaluation showed the migration of one revision cage 12 months after surgery. Revision arthroplasty performed after 14 months revealed the partial incorporation of bone graft substitute. There were not any cases of loosening of revision acetabular cup at the most recent follow up examination in the remaining 39 patients. Bone graft substitute was not absorbed in all of these patients. The survival after 10 years amounted to 97.56%.

CONCLUSION

Bone graft substitute Bone Save may be suitable for acetabular revision surgery, however preoperative bone defect is critical for success and determining of a surgical technique, so this is multifactorial in this challenge surgery.

Reconstruction options and outcomes for acetabular bone loss in revision hip arthroplasty

Revision total hip arthroplasty in the setting of acetabular bone loss is a challenging procedure and requires a solid understanding of current acetabular reconstruction options. Despite major developments in the field of revision hip surgery in recent decades, reconstruction of acetabular defects remains a major problem in order to achieve primary stability and durable fixation without sacrificing additional bone stock. Although there are several ways to classify acetabular bone defects, the Paprosky classification system is the most commonly used to describe the defects and guide treatment strategy. An understanding of the bone defects associated with detailed pre-operative assessment and planning are essential elements in order to achieve satisfactory outcomes. Multiple acetabular reconstructive options are currently available including impaction bone grafting with metal mesh, reinforcement rings and antiprotrusio cage, structural allografts, cementless hemispherical cups, extra-large "jumbo cups", oblong cups, modular porous metal augments, cup-cage constructs, custom- made triflange cups, and acetabular distraction. To date, debate continues as to which technique is most effective due to the lack of long-term studies of modern reconstruction systems. Further long-term studies are necessary to assess the longevity of the different implants. The purpose of this study was to review the current literature and provide a comprehensive understanding of the available reconstruction options with their clinical outcomes.

Deeper Central Reaming May Enhance Initial Acetabular Shell Fixation

Background

The initial stability of press-fit acetabular components is partially determined by the reaming technique. Nonhemispherical (NHS) acetabular shells, which have a larger radius at the rim than the dome, often require larger reaming preparations than the same-sized hemispherical (HS) shells. Furthermore, deeper central reaming may provide a more stable press fit. Using a reproducible, in vitro protocol, we compared initial shell stability under different reaming techniques with HS and NHS acetabular components.

Methods

Cavities for 54-mm NHS and 56-mm HS acetabular components were premachined in 20-pcf Sawbones blocks. Acetabular cavities included diameters of 54, 55, “54+,” and “55+”. “+” indicates a cavity with a 2-mm smaller diameter that is 2-mm deeper. A 4750N statically applied force seated shells to a height that was comparable with shell height after an orthopaedic surgeon’s manual impaction. Force required to dislodge shells was assessed via a straight torque-out with a linear load.

Results

Increased preparation depth (+) was associated with deeper shell seating in all groups. Deeper central reaming increased required lever-out force for all groups. Overall, HS and NHS implants prepared with 55 + preparation had the highest lever-out forces, although this was not significantly higher than those with 54+.

Conclusions

In 20-pcf Sawbones, representing dense bone, overreaming depth by 1-mm improved initial seating measurements. In both HS and NHS acetabular shells, seating depth and required lever-out force were higher in the “+” category. It is unclear, however, whether a decreased diameter ream increased seating stability (55+ vs 54+). Clinically, this deeper central reaming technique may help initial acetabular stability.

Protrusion of a ceramic femoral head through the acetabular metallic cup in total-hip arthroplasty: A case report

RATIONALE

Dislocation, wear, metallosis, and implant loosening are well-known complications of a failed total-hip arthroplasty (THA), and acetabular liner dissociation is an uncommon but catastrophic complication. To our knowledge, this is the first description of metallosis due to acetabular liner dissociation, but not presenting as a result of wear of a metal-on-metal articulation and a polyethylene liner of other articulation.

PATIENT CONCERNS

We described a 61-year-old man who had a 2-year history of pain in the right groin region after THA. Postoperative period of primary THA was uneventful. However, he did not undergo postoperative follow-up, and often participated in strenuous sports activities including mountain climbing and long-distance running.

DIAGNOSIS

Radiographs demonstrated superior subluxation of the femoral head and direct articulation and abrasion wear of the ceramic femoral head on the cup. Preoperative laboratory data revealed no signs of infection.

INTERVENTIONS

We performed revision THA using a direct lateral approach with ceramic-on-ceramic hip prosthesis.

OUTCOMES

Postoperatively, the patient wore a hip orthosis for 6 weeks to prevent dislocation but was allowed full weight bearing. At 1-year follow-up, there was no recurrence of hip pain.

LESSONS

Wear of THA components can result in catastrophic failure of the implants and significant soft-tissue metallosis. Therefore, regular postoperative follow-up is necessary for early intervention, even in those with asymptomatic hips.

Inferior extended fixation utilizing porous titanium augments improves primary anti-rotational stability of the acetabular component

BACKGROUND

The primary anti-rotational stability is critical to preventing cup tilting failure following revision total hip arthroplasty, but is frequently compromised by severe ischial bone loss. A novel technique of "inferior extended fixation" was introduced by securing a porous metal augment into the deficient ischium. This study evaluated the effect of this technique on primary anti-rotational stability in revision total hip arthroplasty.

METHODS

Composite hemipelvis specimens, acetabular components and "lotus" augments were used to simulate total hip arthroplasty surgeries. Three different cementless operative settings of cup implantation were simulated: (1) native ischium without defects; (2) ischium with a defect not reconstructed; (3) ischial defect reconstructed with inferior extended fixation using a lotus augment. Lever-out testing was used to examine primary anti-rotational stability, which was measured as interface stiffness and yield moment.

FINDINGS

Compared with the native ischium setting, the mean interface stiffness decreased by 53.1% in the ischial defect setting (p < 0.001). In the inferior extended fixation setting, the mean value was 110% greater than that in the ischial defect setting (p = 0.014), and comparable to that in the native ischium setting (p = 1). Similar results were observed for the yield moment (declined by 63.1%, p < 0.001; 200% higher, p < 0.001; and p = 0.395; respectively).

INTERPRETATION

In revision total hip arthroplasty with severe ischial defects, inferior extended fixation with a lotus porous titanium augment restores anti-rotational stability of the acetabular component to the level of that with a native ischium, which provides the mechanical environment for bone ingrowth and prevents cup tilting failure.

Reconstruction of failed acetabular component in the presence of severe acetabular bone loss: a systematic review

Acetabular revision especially in the presence of severe bone loss is challenging. There is a paucity of literature critiquing contemporary techniques of revision acetabular reconstruction and their outcomes. The purpose of this study was to systematically review the literature and to report clinical outcomes and survival of contemporary acetabular revision arthroplasty techniques (tantalum metal shells, uncemented revision jumbo shells, reinforced cages and rings, oblong shells and custom-made triflange constructs). Full-text papers and those with an abstract in English published from January 2001 to January 2016 were identified through international databases. A total of 50 papers of level IV scientific evidence, comprising 2811 hips in total, fulfilled the inclusion criteria and were included. Overall, patients had improved outcomes irrespective of the technique of reconstruction as documented by postoperative hip scores. Our pooled analysis suggests that oblong cups components had a lower failure rate compared with other different materials considered in this review. Custom-made triflange cups had one of highest failure rates. However, this may reflect the complexity of revisions and severity of bone loss. The most common postoperative complication reported in all groups was dislocation. This review confirms successful acetabular reconstructions using diverse techniques depending on the type of bone loss and highlights key features and outcomes of different techniques. In particular, oblong cups and tantalum shells have successful survivorship.

[Treatment of acetabular bone defects in revision hip arthroplasty using the Revisio-System]

BACKGROUND

Many different systems for the management of primary and secondary acetabular defects are available, each with its inherent advantages and disadvantages. The Revisio-System is a press-fit oval mono-block implant that makes a defect-oriented reconstruction and restoration of the center of rotation possible.

MATERIAL AND METHODS

In this study, we retrospectively reviewed the outcome of 92 consecutive patients treated with this oval press-fit cup due to periacetabular bone loss. The average follow-up was 58.2 months. Defects were classified according to D'Antonio. There were 39 type II, 38 Type III, and 15 type IV defects. After an average of 4.9 years, the implant survival rate was 94.6% with cup revision as the end point and 89.1% with revision for any reason as the end point. The Harris Hip Score increased from 41.1 preoperatively to 62.3 postoperatively. The mean level of pain measured with the Visual Analogue Scale (VSA) was reduced from 6.9 preoperatively to 3.8 postoperatively.

RESULTS

The Revisio-System represents a promising toolbox for defect-orientated reconstruction of acetabular bone loss in revision hip arthroplasty. Our results demonstrate that the implantation of the Revisio-System can result in a good mid-term clinical outcome.

A 2- to 7-Year Follow-Up of a Modular Iliac Screw Cup in Major Acetabular Defects: Clinical, Radiographic and Survivorship Analysis With Comparison to the Literature

BACKGROUND

Inadequate acetabular bone stock is a major issue in total hip arthroplasty, and several treatment options are available. Stemmed cups have been used in this scenario with variable results. A novel modular polyaxial uncemented iliac screw cup (HERM-BS-Sansone cup-Citieffe s.r.l., Calderara di Reno, Bologna, Italy) has been recently introduced to overcome the drawbacks of stemmed cups. In this retrospective study, we report the results of this cup in patients with large acetabular bone defects at 2- to 7-year follow-up.

METHODS

We evaluated a consecutive series of 121 hips (118 revisions and 3 complex primary arthroplasties) treated with this novel cup at a mean follow-up of 46 months. Kaplan-Meier survival analysis was performed with implant revision for any reason as a primary end point. Further survival analysis was performed excluding septic failures. Clinical outcome was assessed with the Harris Hip Score.

RESULTS

There had been 7 reoperations: 1 for aseptic loosening, 5 for deep infection, and 1 for recurrent dislocation. In 5 cases, the cup was removed; estimated survival rate at 5-year follow-up with implant removal for any reason was 95.6% (95% confidence interval = 91-99), and 98.3% (95% CI = 96-100) excluding those failed for infection. Mean Harris Hip Score at latest follow-up was 77 points (range, 44-95; standard deviation = 11.9).

CONCLUSION

The present findings show the short-term efficacy of the iliac screw cup with respect to implant survival. A longer follow-up and a larger number of patients are necessary to confirm the encouraging preliminary results.

The Use of Structural Distal Femoral Allograft for Acetabular Reconstruction of Paprosky Type IIIA Defects at a Mean 21 Years of Follow-Up

BACKGROUND

Revision total hip arthroplasty in patients with a nonsupportive superior acetabulum often requires secondary augmentation beyond a hemispherical cup to achieve reliable fixation. Treatment options include using a higher hip center, jumbo cup, custom triflange implant, cages, or filling the superior defect with a bilobed implant, structural allograft, or metal augments. We previously reported a cohort of 31 patients treated with porous-coated hemispherical cups and distal femoral allograft for Paprosky type IIIA acetabular defects.

METHODS

The original cohort of 31 hips was retrospectively reviewed. Fourteen patients died with <15 years of follow-up, and 2 were lost to follow-up. This left 15 patients for evaluation including 5 males and 10 females, with an average age of 61 years (range: 37-74 years) at the time of surgery. Acetabular revision was performed with the use of a porous-coated hemispherical cup along with structural distal femoral allograft, cut to resemble the number 7, and secured with 6.5-mm cancellous screws with washers.

RESULTS

Overall, 7 hips failed, resulting in a Kaplan-Meier survivorship of 72% at 25 years of follow-up. In surviving patients, radiographs demonstrated components to be well fixed, and average Merle d'Aubigné score increased from 5 to 10 points. There were a subset of patients that failed early (median: 6.2 years), but the remaining patients demonstrated excellent clinical and radiographic results.

CONCLUSIONS

The use of distal femoral allograft can be considered in young patients with type IIIA acetabular defects that could benefit from restoration of bone stock.

Role of Cages in Revision Arthroplasty of the Acetabulum

➤ The outcome of acetabular revision is heavily influenced by the degree of associated bone loss.➤ Uncemented hemispherical acetabular components can be used in the majority of acetabular revisions, although occasionally the degree of bone loss precludes the stability of the hemispherical component at the correct anatomic level or there is minimal bleeding host bone left for biologic fixation.➤ Massive acetabular bone loss resulting in the need for bone grafts or highly porous augments involving more than half of the acetabulum is one of the main indications for the use of cages.➤ The cup-cage reconstruction is based on bone-grafting the deficient acetabulum and securing a hemispherical, highly porous metal component with multiple screws to bridge the discontinuity and off-loading the hemispherical component with a titanium cage spanning from ischium to ilium.➤ In addition to managing pelvic discontinuities, the cup-cage construct can also be used in hips without discontinuity as the hemispherical, highly porous metal component is used to restore bone stock.➤ In situations in which there is not enough bleeding host bone to secure a hemispherical component, a highly porous metal augment can be used to address the osseous deficiency. The augment is also protected with a cage to assist bone ingrowth.

Satisfying outcomes scores and survivorship achieved with impaction grafting for revision THA in young patients

BACKGROUND

The increasing number of total hip arthroplasties (THAs) performed in younger patients will inevitably generate larger numbers of revision procedures for this specific group of patients. Unfortunately, no satisfying revision method with acceptable survivorship 10 years after revision has been described for these patients so far.

QUESTIONS/PURPOSES

The purposes of this study were to (1) analyze the clinical outcome; (2) complication rate; (3) survivorship; and (4) radiographic outcome of cemented revision THA performed with impaction bone grafting (IBG) on both the acetabular and femoral sides in one surgery in patients younger than 55 years old.

METHODS

During the period 1991 to 2007, 86 complete THA revisions were performed at our institution in patients younger than 55 years. In 34 of these 86 revisions (40%), IBG was used on both the acetabular and femoral sides in 33 patients. Mean patient age at revision surgery was 46.4 years (SD 7.6). No patient was lost to followup, but three patients died during followup. None of the deaths were related to the revision surgery. The mean followup for the surviving hips was 11.7 years (SD 4.6). We also analyzed complication rate.

RESULTS

The mean Harris hip score improved from 55 (SD 18) preoperatively to 80 points (SD 16) at latest followup (p = 0.009). Six hips underwent a rerevision (18%): in four patients, both components were rerevised; and in two hips, only the cup was revised. Patient 10-year survival rate with the endpoint of rerevision for any component for any reason was 87% (95% confidence interval [CI], 67%-95%) and with the endpoint of rerevision for aseptic loosening, the survival rate was 97% (95% CI, 80%-100%). In total six cups were considered radiographically loose, of which four were rerevised. Three stems were radiographically loose, of which none was rerevised.

CONCLUSIONS

IBG is a valuable biological revision technique that may restore bone stock in younger patients. Bone stock reconstruction is important, because these patients likely will outlive their revision implants. Bone reconstruction with impaction grafting may facilitate future revisions.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Radiography versus multidetector computed tomography in assessing graft integration after acetabular reconstruction

PURPOSE

To compare radiography with multidetector computed tomography (MDCT) in the evaluation of graft integration following acetabular reconstruction for failed total hip arthroplasty (THA).

METHODS

Records of 5 men and 6 women aged 60 to 78 (mean, 71.8) years who underwent acetabular reconstruction using structural allografts for severe acetabular deficiency secondary to aseptic loosening (n=9) or septic loosening (n=2) were reviewed. The mean survival time of the THA was 136.4 (range, 12-360) months. Acetabular defects were classified as IIC (n=2), IIIA (n=3), or IIIB (n=6). Structural allografts were fixed with impaction followed by a reinforcement ring (n=10), an antiprotrusio cage (n=2), and/or an oblong cup (n=1) with gentamicineloaded cement. Cup loosening, graft integration, and graft resorption were evaluated using radiography. In addition, graft integration was evaluated using MDCT.

RESULTS

At a mean follow-up of 4.2 (range, 2-11) years, the survival of the acetabular reconstruction was 90.9%. No patient had any signs of infection. One patient underwent reoperation 22 months later for dislocation secondary to abductor deficiency caused by nonunion of the trochanteric fracture. According to radiography, all patients had graft integration. One patient had definitive and another had possible cup loosening. Four patients had minor graft resorption. According to MDCT, graft integration was complete in only one patient, partial >50% in 3, partial <50% in 4, and absent in 2.

CONCLUSION

MDCT is more accurate than radiography in evaluating graft integration following acetabular reconstruction.

Massive bone defect compromises postoperative cup survivorship of acetabular revision hip arthroplasty with impaction bone grafting

We evaluated 66 acetabular revision arthroplasties using cemented cup with impaction bone grafting (IBG) to detect the extent that bone defect affects the outcome. We defined the maximum acetabular defect distance (MADD), which indicates the greatest depth of the grafted layer. Cup survival analysis with aseptic loosening as the endpoint revealed that the "MADD≤20mm" group showed higher survivorship than the "MADD>20mm" group (95% vs. 74%, P=0.034), and that the simple-wall-defect group (none or one mesh used) showed higher survivorship than the complex-wall-defect group (two meshes used) (96% vs. 73%, P=0.044). A favorable indication for acetabular IBG reconstruction is cases in which those cups can be placed at≤20mm MADD with a simple wall defect.

Mid-term results of revision total hip arthroplasty using the oval-shaped uncemented Trč-Cingr cup

PURPOSE

The aim of the present study was to introduce a novel oblong revision cup type TC for use in revision total hip arthroplasty (THA), and to evaluate mid-term results in terms of bone tissue remodelling in the immediate area of the implant.

METHODS

The results of 31 patients that underwent revision THA between 2004 and 2008 are presented. The mean follow-up interval was 7.1 years (range 5.3-9.3 years, minimum of five years following revision). Osteointegration of the implant and bone tissue remodelling around the implant and ribs were assessed by X-ray and computed tomography (CT).

RESULTS

The average Harris hip score increased from 39.8 to 85.3. Excellent results were achieved in nine patients, good in 16, fair in three and poor in three. According to X-ray results, 25 hips had a well-fixed, bone-ingrown cup and five had a stable fibrous union in the middle and the distal third of the implant. Proximal migration of the cup was noted in one case. Pelvic CT was additionally performed in ten patients. In all cases, we detected bone remodelling in the space between the implant ribs. Kaplan-Maier survivorship of the acetabular components was 94.2 % at 7.1 years.

CONCLUSIONS

Our results show that the novel oblong revision cup type TC is relatively simple to implant, and is associated with reliable primary fixation and documented osteointegration and bone remodelling in the immediate area.

A long-term survivorship comparison between cemented and uncemented cups with shelf grafts in revision total hip arthroplasty after dysplasia

Long-term outcomes of cemented and uncemented cups were compared in patients with hip dysplasia who had undergone revision hip arthroplasty. Patients had uncontained superolateral acetabular defects reconstructed with a structural allograft. This retrospective study compared 18 cemented acetabular cups to 27 uncemented acetabular cups. Average follow-up was 216 months (range, 96-312). Nineteen acetabular cups (42%) failed due to loosening and were revised. The 10- and 20-year cup survival was 88% and 76% in the uncemented group and 67% and 36% in the cemented group. Log rank analysis showed this difference to be significant (P = .0077). Uncemented acetabular cups performed significantly better than cemented cups.

Acetabular revision surgery with the uncemented oblong BOFOR Cup--early to midterm results

INTRODUCTION

Failure of acetabular components frequently leads to bone loss with extensive elongated defects in the surrounding bone. In these cases the use of an oblong cup has been described as an option for acetabular reconstruction. We report the longest follow up results obtained with this implant to date.

MATERIALS AND METHODS

A prospective study was conducted to evaluate the results of the BOFOR oblong revision cup. Between 2001 and 2006, 15 acetabular revisions were performed for aseptic loosening of the acetabular cup. The acetabular defects were classified as type 2A to 3A, according to Paprosky's criteria. No allografts were used in any of the cases. The mean follow-up was 90 months (range 60-120 months).

RESULTS

Clinical assessment at follow-up showed a significantly improved mean Harris Hip Score from 39 points preoperatively to 84 points postoperatively and a mean Oxford Hip Score from 55 points preoperatively to 22 points postoperatively. Only one case underwent re-revision due to aseptic loosening in a patient with severe ankylosing spondylitis. There were no cases of dislocation or infection. One patient had a sciatic nerve neurapraxia. After an average follow up of 7.5 years, 93% of the investigated implants remained in-situ without further revision.

CONCLUSION

This study shows that the BOFOR cup provided good clinical results and showed satisfactory stability at early to midterm follow-up.

Improving initial acetabular component stability in revision total hip arthroplasty calcium phosphate cement vs reverse reamed cancellous allograft

A reproducible retroacetabular defect was created bilaterally in 9 cadaver pelves. The defects were filled with either an injectable, bioresorbable, calcium phosphate cement, or reverse-reamed cancellous allograft. An uncemented acetabular shell was impacted, followed by the placement of an appropriate liner. The pelves were then sectioned, and each half was loaded in a material testing machine to simulate walking on the construct over a several week period. The cement-filled defects lasted a greater number of cycles before failure and had greater cup stability and stiffness. The use of resorbable bone void filler for retroacetabular defects shows promise in this biomechanical analysis. Long-term clinical follow-up is warranted to track osseointegration of the implant and restoration of bone stock between this and other clinically accepted surgical techniques.

High complication rate in reconstruction of Paprosky type IIIa acetabular defects using an oblong implant with modular side plates and a hook

We report the results of 62 hips in 62 patients (17 males, 45 females) with mean age of 62.4 years (37 to 81), who underwent revision of the acetabular component of a total hip replacement due to aseptic loosening between May 2003 and November 2007. All hips had a Paprosky type IIIa acetabular defect. Acetabular revision was undertaken using a Procotyl E cementless oblong implant with modular side plates and a hook combined with impaction allografting.

At a mean follow-up of 60.5 months (36 to 94) with no patients lost to follow-up and one died due to unrelated illness, the complication rate was 38.7%. Complications included aseptic loosening (19 hips), deep infection (3 hips), broken hook and side plate (one hip) and a femoral nerve palsy (one hip). Further revision of the acetabular component was required in 18 hips (29.0%) and a further four hips (6.4%) are currently loose and awaiting revision.

We observed unacceptably high rates of complication and failure in our group of patients and cannot recommend this implant or technique.

Cementless acetabular revision: past, present, and future. Revision total hip arthroplasty: the acetabular side using cementless implants

BACKGROUND

Acetabular revision is probably the most difficult aspect of hip reconstructive surgery. Although the majority of acetabular revisions can be performed using an uncemented hemispherical acetabular device with ancillary fixation, patients with severe acetabular deficiencies and poor bone quality require more complex alternatives for revision. The limitations of traditional cementless acetabular implants has promoted the development of improved methods of fixation and revision techniques. Highly porous metals have been introduced for clinical use in arthroplasty surgery over the last decade. Their higher porosity and surface friction are ideal for acetabular revision, optimising biological fixation. The use of trabecular metal cups in acetabular revision has yielded excellent clinical results.

PURPOSE

This review focuses on the use of cementless implants for acetabular revision. The use of trabecular metal cups, augments, jumbo cups, oblong cups, cages, and structural grafting are also discussed.

[Standardized reconstruction of acetabular bone defects using the cranial socket system]

OBJECTIVE

Management of primary or secondary acetabular bone loss (D'Antonio type I-IV ). Implantation and stable fixation using a cementless, cranially extended oval press-fit cup to restore painless joint function and loading capacity.

INDICATIONS

Septic or aseptic loosening of the acetabular component after total hip arthroplasty. Acetabular bone loss after tumor resection. Primary acetabular bone defects in developmental dysplasia of the hip.

CONTRAINDICATIONS

Persistent deep infection. Bone defects including the parts of the iliac bone adjoining the sacrum (fixation of the stem in the ilium is not possible any more).

SURGICAL TECHNIQUE

Complete exposure of the acetabular defect using a standard approach. Removal of the loose cup. Excision of soft and granulation tissue from the acetabular ground and the rim. Reaming of the acetabulum with sequentially larger hemispheric reamers until an adequate bony bed is created for the insertion of the cranial socket. Eccentric cranial sockets without a craniolateral flap are preferable for use in type I and II defects with teardrop lysis mostly involving the craniolateral acetabulum, if a trihedral press-fit fixation can be achieved. Supplementary screw fixation through the acetabular ground, is possible. If a type III defect is present, the authors recommend the use of cranial sockets with an anatomic flap in order to increase primary stability by supplementary screw fixation. This is especially recommended for the management of deficiencies in the medial or posterior wall. If there is pelvic discontinuity (type IV), adequate acetabular reconstruction with primary stability of the component can only be achieved by a supplementary intramedullary structured stem fixed in the dorsal part of the ilium.

POSTOPERATIVE MANAGEMENT

Partial loading of the operated limb with 10 kg for a period of 6-12 weeks. Then increased loading with 10 kg per week. Thrombosis prophylaxis until full weight bearing. Physiotherapy and gait training.

RESULTS

A total of 50 cup revisions using the ESKA cranial socket system were clinically and radiologically analyzed with an average follow-up of 65.7+/-28.5 months (26-123 months). Defects were classified according to D'Antonio. There were 21 type II, 23 type III, and six type IV defects. The Harris Hip Score increased from 40 preoperatively to 68.3 points postoperatively. Four patients had recurrent hip dislocation requiring replacement of the inlay. In four cases of aseptic loosening, the acetabular component had to be revised. With revision of the acetabular component as an endpoint, implant survival was 92% after an average of 5.4 years.

[Comparison of different cup revision systems]

Aseptic loosening of hip cups results in cranial and medial migration, which induces bone resorption and defects. Despite these defects, it is the aim in cup revision arthroplasty to get a stable fixation and a restoration of the hip center. Depending on the size of the defect, which can be classified by different scoring systems, various strategies requiring an experienced surgeon can be used to reach this aim. If defects are localized, bigger primary cemented or cement-free cups can be used. Larger defects may need bone transplantation or special designs such as oval cups or reinforcement rings. They can be used with or without plates in combination with cement for inlay fixation. In the case of bigger defects or pelvic discontinuity, modular systems or a socket cup may be necessary.

[Acetabular revision surgery with the oblong revision cup : clinical and radiological results of 217 cases]

BACKGROUND

Deficiencies of the acetabular bone stock are an increasing and challenging problem in revision hip surgery. The LOR oblong revision cup is a valuable option in revision hip surgery. The purpose of this study was to assess outcomes with the LOR revision cup in hips with acetabular bone deficiency, analyze the complications, and identify predictors of survival rate.

PATIENTS AND METHODS

From 1996 to 2002, 217 revision surgeries were performed with LOR cups. The mean patient age at operation was 67.5 years (range 29-87 years). The mean postoperative follow-up was 4 years (range 4-100 months). The patients were evaluated clinically and with the Harris hip score (HHS), UCLA score, and WOMAC index. A continuous radiographic assessment was done to detect heterotopic ossifications and radiolucencies or loosening on the basis of the Mayo hip score. Predictors of survival rate were estimated using Kaplan-Meier survivorship analysis.

RESULTS

Twenty-four patients (7.4%) died during the study period. Seven patients (3.1%) had revisions because of aseptic loosening and two patients (0.9%) because of infection. Clinical assessment at follow-up showed a significantly improved mean HHS from 45 points preoperatively to 78 points postoperatively. At the most recent follow-up, patients with a body mass index below 30 or those classified as Charnley A had a significantly better HHS. Because of migration on the latest radiographs, revision was indicated in 4.8% of the cases. The survival rate of all LOR implants based on implant removal was 96% after 40 months and 87% after 80 months. Based on radiographic evidence of loosened implants, the survival rate was 94% after 40 months and 79% after 80 months. Patients with more than two revisions had reduced implant survivorship compared with those having one or two revisions. The factors "age at operation", "gender", "obesity", "ASA score", "Charnley score", and "activity according to the UCLA score" did not influence the survival rate.

CONCLUSION

We recommend this component in revision surgery on the basis of satisfactory clinical and radiological results at a mean of 48 months of follow-up. We identified the number of revisions as a predictor of survival rate.

Revision of failed acetabular components utilizing a cementless oblong cup: an average 9-year follow-up study

INTRODUCTION

Failure of acetabular components often leads to bone loss with extensive elongated defects in the surrounding bone. In these cases, reconstruction is challenging and stable fixation of the revision implant difficult. The use of an oblong cup has been described as an option for acetabular reconstruction in such revisions. We report the first long-term results obtained with this implant to date.

MATERIALS AND METHODS

Fifty-six longitudinal oblong revision cups (LOR) were evaluated clinically and radiologically after a follow-up of 8-12 years (average 9 years). The defects treated with the LOR cup ranged from Paprosky type 1-3. Allogenic cancellous bone chips were additionally used in 31 reconstructions to fill cavitary defects.

RESULTS

Based on radiological criteria, 50 acetabular implants underwent osseointegration without any definitive signs of loosening; 2 consistently exhibited zonal radiolucent lines that were always smaller than 2 mm, 1 migrated by around 3 mm. None of these cases exhibited any clinical symptoms. In 11 cases where acetabular defects manifested postoperatively, 8 were remodeled completely and 3 partially at final follow-up. Three revision implants migrated farther than 5 mm and had to be revised before 32-month follow-up. In addition, 1 septic implant failure occurred. After an average follow-up of 9 years, 93% of the investigated implants remained in situ without further revision and 95% without aseptic implant failure.

CONCLUSION

This 12-year clinical study demonstrates that the LOR cup offers a successful concept for the revision of failed acetabular components that also promotes the biological reconstruction of bony defects. Compared with other methods with similarly long follow-ups, our long-term results prove this procedure has a very low rate of revision and aseptic implant failure.

Clinical and radiographic assessment of cementless acetabular revision with morsellised allografts

The aim of this study was to evaluate the clinical and radiographic results of cementless acetabular revision with deep frozen morsellised allografts. Sixty-one patients (65 hips) underwent acetabular revision using cementless components and deep frozen morsellised allografts. Fifty-seven hips (53 patients) were reviewed at a mean of 105.1 months (range 72-180 months) after revision. The study group included 29 males and 24 females with a mean age of 46.4 years. One cup underwent further revision for aseptic loosening and two were defined as radiographic failures. The mean time for allograft incorporation was 12.5 months (range 6-24 months) after index surgery. The mean Harris hip score of the patients improved from 61.1 points preoperatively to 91.6 points postoperatively. Linear and cavitary osteolysis was observed in two and 12 hips, respectively. The acetabular revision using cementless components with deep frozen morsellized allografts provides favourable clinical and radiographic results, although the initial disease and age may adversely affect the outcomes.