Early outcome of a modular femoral component in revision total hip arthroplasty

Revision Hip Arthroplasty Using a Modular, Cementless Femoral Stem: Long-Term Follow-Up

BACKGROUND

As the number of primary total hip arthroplasty (THA) cases increase, so does the demand for revision operations. However, long-term follow-up data for revision THA is lacking.

METHODS

A retrospective review was completed of patients who underwent revision THA at a single institution between January 2002 and October 2007 using a cementless modular stem. Patient demographic, clinical, and radiographic data was collected. Preoperative and postoperative patient-reported outcome scores were compared at a minimum of fourteen-year follow-up.

RESULTS

Eighty-four patients (89 hips) with a median age of 69 years (range, 28 to 88) at operation were included. Indications for revision included aseptic loosening (84.2%), infection (12.4%), and periprosthetic fracture (3.4%). Twenty-two hips sustained at least 1 complication: intraoperative fracture (7.9%), dislocation (6.7%), prosthetic joint infection (4.5%), deep venous thrombosis (3.4%), and late periprosthetic fracture (2.2%). There were no modular junction complications. Eight patients underwent reoperations; only three involved the stem. Thirty-eight patients (45%) were deceased prior to final follow-up without known reoperations. Twenty-seven patients (32%) were lost to follow-up. Twenty-one patients (23%) were alive at minimum fourteen-year follow-up. Complete patient-reported outcomes were available for nineteen patients (range, 14 to 18.5 years of follow-up). Significant improvement was seen in UCLA activity, VR-12 physical, hip disability and osteoarthritis outcome score , joint replacement., and Harris Hip score pain and function scores.

CONCLUSION

Challenges of long-term follow-up include patient migration, an unwillingness to travel for re-examination, medical comorbidities, advanced age, and death. The cementless modular revision stem demonstrated long-term clinical success and remains a safe and reliable option for complex revision operations.

Influence of bone morphology and femur preparation method on the primary stability of hip revision stems

Aseptic loosening is one of the major reasons for re-revisions of cementless revision stems. Insufficient primary stability is associated with bone characteristics and the surgical process. This study aimed to investigate how femur morphology and preparation methods influence the primary stability of revision stems. The Femur morphology was described by the upper femoral curvature (UFC) and an individualized Dorr type classification based on the ratio between the canal-to-calcar ratio (CCR*) and the cortical index (CI*) introduced as the cortical-canal shape (CCS). Manual and powered reaming in combination with helical and straight reamers were used to prepare the bone cavity of 10 cadaveric human femur pairs. Forces during stem impaction were recorded (Reclaim, Depuy Synthes). Micromotion at the bone-implant interface during cyclic axial loading and torsional load to failure was determined. The CCS and impaction forces (R²  = 0.817, p < 0.001) or torsional strength (R²  = 0.577, p < 0.001) are inversely related. CCS did not correlate with micromotion during axial loading (R²  = 0.001, p > 0.999), but proximal femoral curvature did (R²  = 0.462, p = 0.015). Powered reaming and straight reamers led to an improved torsional strength (both: p = 0.043). The Individualized Dorr classification CCS and UFC allows a good estimation of the primary stability of revision stems. For severely curved Dorr type-C femurs, an alternative anchorage method should be considered clinically.

Stay Short or Go Long in Revision Total Hip Arthroplasty With Paprosky Type II Femoral Defects: A Comparative Study With the Use of an Uncemented Distal Fixating Modular Stem and a Primary Monobloc Conical Stem With 5-Year Follow-Up

BACKGROUND

In the revisions for Paprosky type II femoral defects, diaphyseal fixating femoral stems are commonly used. To preserve bone stock, the use of a shorter primary conical stem could be an adequate alternative. The objective of this study is to compare the results of a primary conical stem to the more commonly used diaphyseal fixating modular revision stem in revision total hip arthroplasty surgery with Paprosky type II femoral defects.

METHODS

A total of 59 consecutive patients with Paprosky type II femoral defects from our prospective revision registry were included. Thirty patients who received a long distal fixating modular stem (Revision Stem, Lima Corporate) and 29 patients who received a primary conical short stem (Wagner Cone, Zimmer) were prospectively followed. Minimal follow-up time was 2 years for subsidence and patient-reported outcome measures and 5 years for complications, reoperation, and revision. We compared subsidence, perioperative complications, reoperations, femoral component survival, Oxford Hip Score, EuroQol 5 Dimension, visual analog scale (VAS) for pain at rest, and VAS for pain during activity between stems.

RESULTS

Both groups were comparable regarding demographic, clinical, and surgery-related characteristics. We found more perioperative complications and stem revisions with the modular revision stem than with the primary conical stem. There were no statistical differences in subsidence, EuroQol 5 Dimension, Oxford Hip Score, and VAS for pain at rest or during activity between both stems.

CONCLUSION

In revision total hip arthroplasty with Paprosky type II femoral defects, uncemented primary monobloc conical femoral stems showed the same clinical result as distal fixating modular stems with fewer complications and fewer stem revisions.

Does metaphyseal modularity in femoral revision stems have a role in treating bone defects less severe than IIIB? Clinical and radiological results of a series of 163 modular femoral stems

INTRODUCTION

Revision for loosening of femoral stems requires an extensive analysis of bone defects to determine the most appropriate course of action. The drawbacks of using modular stems are that they can break or corrode at their junction. They have rarely been evaluated based on the extent of bone loss and particularly in patients with less severe bone loss. This led us to carry out a retrospective study to analyze modular femoral stems as a function of the initial bone defect (stage IIIB versus less severe in the Paprosky classification): 1) implant survivorship, 2) osteointegration and subsidence of the stem, and 3) breakage of implant.

HYPOTHESIS

Modular femoral stems can be used for all types of bone defects (not only IIIB) as the complication rate is identical.

PATIENTS AND METHODS

Between January 1, 1996, and December 31, 2016, 163 patients were included who had received a modular femoral revision stem. The minimum follow-up was 4 years; the mean was 6.7 years±3.3 [4-21]. One patient was lost to follow-up, 88 had died before the analysis date and 74 were still alive; however, 10 of them had the stem removed less than 4 years after implantation. Thus 64 patients were available for the clinical evaluation. There were 44% (72 patients) with Paprosky stage IIIB femoral bone loss and 56% (91 patients) with stage I, II or IIIA bone loss. The stem's bone integration was evaluated using the Engh and Massin score. All complications were documented.

RESULTS

The survivorship of the femoral stem was 93.75% (95% CI: 83.33-96.70) at 5 years with removal for any reason as the end point. There was no significant difference (p=0.0877) in survivorship relative to the severity of the initial bone loss: 89.84% (95% CI: 78.73-95.31) for stage IIIB; 95.23% (95% CI: 82.24-98.79) for stage IIIA; 97.06% (95% CI: 80.90-99.58) for stage II. Bone integration was considered as being achieved in 76% of stems based on available radiographs (119 of 156 patients) with the severity of bone loss having no effect. We found 18 instances of stem subsidence out of 156 stems with available data (11.5%). The mean subsidence was 14.7 mm ± 12.3 [5-40]. Among the 18 stems with postoperative subsidence, 13 had been implanted for stage IIIB defects, while 5 were for less severe defects (p=0.751). Two stem fractures occurred in patients with stage IIIB bone loss, thus 2/66 for stage IIIB and 0/86 in the less severe bone loss cases (p=0.188).

CONCLUSION

Modularity provides similar results no matter the severity of initial bone loss, without the risk of additional complications.

LEVEL OF EVIDENCE

IV, Retrospective study.

Distal fixation stems for revision of total hip replacement

The purpose of this study was to retrospectively assess patients treated with modular, non-cemented, tapered, fluted, distal fixation stems. We included patients with 24 months mínimum follow-up. Diagnosis that led to revisions were described. The radiographic analysis was made with preoperative, immediate postoperative and last control postoperative X-rays. Sixty-seven patients met inclusion criteria. We observed 59,7% (n=40) Osteointegration, 34,3% of Stable Fibrosis and 5,97% Unstable fibrosis. Stress Shielding was registered with 10,44% and Subsidence was observed in 34,3% of the patients. Modular, fluted, tapered, distal fixation stems have an excellent survival rates.

Revision Hip Arthroplasty Using a Porous-coated or Taper ZMR Implant: Minimum 10-year Follow-up of Implant Survivorship

INTRODUCTION

The Zimmer Modular Revision hip (ZMR) system is available in two stem options, a porous-coated cylindrical (PCM) and a taper (TM) stem. Several concerns have been reported regarding modular implants. Specifically, because of early junctional fractures, the ZMR system was redesigned with a wider modular interface. As such, we designed a study assessing long-term ZMR survivorship and functional and radiographic outcomes.

METHODS AND MATERIALS

A search of our institutional research database was performed. A minimum 10-year follow-up was selected. The following two cohorts were created: PCM and TM stems. The Kaplan-Meier survival analysis was performed, and causes of stem failure requiring revision surgery were collected. Functional outcomes as per the Harris Hip Score and radiographic stem stability were assessed as per the Engh classification.

RESULTS

A total of 146 patients meeting the inclusion criteria were available for follow-up (PCM = 68, TM = 78). The mean follow-up was 13.4 years clinically and 11.1 years radiographically for the PCM cohort. Similarly, the TM cohort had a follow-up of 11.1 years clinically and 10.5 years radiographically. The Kaplan-Meier survivorships were 87.1% and 87.8% at 15 years for the PCM and TM cohorts, respectively. The most common cause of failure requiring revision surgery overall was aseptic loosening (PCM = 1.4%, TM = 5.6%). The mean postoperative Harris Hip Score was as follows: PCM = 71.2 and TM = 64.7. Engh type I or II stem ingrowth was as follows: PCM = 85% and TM = 68%.

DISCUSSION

Good survivorship using the ZMR stem system can be expected at up to 15 years. Aseptic loosening remains the most commonly encountered problem for both PCM and TM stems. Previously identified modular junctional weakness seem to have been addressed.

Outcomes of modular femoral revision implants and the effect of component design on subsidence

AIMS

Femoral revision component subsidence has been identified as predicting early failure in revision hip surgery. This comparative cohort study assessed the potential risk factors of subsidence in two commonly used femoral implant designs.

METHODS

A comparative cohort study was undertaken, analyzing a consecutive series of patients following revision total hip arthroplasties using either a tapered-modular (TM) fluted titanium or a porous-coated cylindrical modular (PCM) titanium femoral component, between April 2006 and May 2018. Clinical and radiological assessment was compared for both treatment cohorts. Risk factors for subsidence were assessed and compared.

RESULTS

In total, 65 TM and 35 PCM cases were included. At mean follow-up of seven years (1 to 13), subsidence was noted in both cohorts during the initial three months postoperatively (p < 0.001) then implants stabilized. Subsidence noted in 58.7% (38/65 cases) of the TM cohort (mean 2.3 mm, SD 3.5 mm) compared to 48.8% (17/35) of PCM cohort (mean 1.9 mm, SD 2.6 mm; p = 0.344). Subsidence of PCM cohort were significantly associated with extended trochanteric osteotomy (ETO) (p < 0.041). Although the ETO was used less frequently in PCM stem cohort (7/35), subsidence was noted in 85% (6/7) of them. Significant improvement of the final mean Oxford Hip Score (OHS) was reported in both treatment groups (p < 0.001).

CONCLUSION

Both modular TM and PCM revision femoral components subsided within the femur. TM implants subsided more frequently than PCM components if the femur was intact but with no difference in clinical outcomes. However, if an ETO is performed then a PCM component will subside significantly more and suggests the use of a TM implant may be advisable. Cite this article: Bone Joint J 2020;102-B(6):709-715.

Is There a Benefit to Modularity for Femoral Revisions When Using a Splined, Tapered Titanium Stem?

BACKGROUND

Proposed benefits of modularity for femoral revisions in total hip arthroplasty (THA) include more precise biomechanical restoration and improved stability, but this has not been proven with use of a splined, tapered design. This study's purpose is to compare (1) complication rates, (2) functional outcomes, and (3) radiographic measures of subsidence, offset, and leg length discrepancy with the use of modular vs monoblock splined, tapered titanium stems in revision THA.

METHODS

We retrospectively reviewed 145 femoral revisions with minimum 2-year follow-up (mean, 5.12 years; range, 2-17.3 years). Patients receiving a modular (67) or monoblock (78) splined, tapered titanium stem for femoral revision were included.

RESULTS

There were no statistically significant differences in rates of reoperation (22.3% vs 17.9%; P = .66), intraoperative fracture (9.0% vs 3.8%; P = .30), postoperative fracture (3.0% vs 1.3%; P = .47), dislocation (11.9% vs 5.1%; P = .23), or aseptic loosening (4.5% vs 6.4%; P = .73) between the modular and monoblock cohorts, respectively. There were similar results regarding subsidence >5 mm (10.4% vs 12.8%; P = .22), LLD >1 cm (35.8% vs 38.5%; P = .74), restoration of hip offset (-5.88 ± 10.1 mm vs -5.07 ± 12.1 mm; P = .67), and Harris Hip Score (70.7 ± 17.9 vs 73.9 ± 19.7; P = .36) between groups. Multivariate regression showed no differences in complications (P = .44) or reoperations (P = .20) between groups.

CONCLUSION

Modular and monoblock splined, tapered titanium stems demonstrated comparable complication rates, functional outcomes, and radiographic parameters for femoral revisions. However, a limited number of patients with grade IIIB or IV femoral bone loss received a monoblock stem. Future investigations are required to determine whether modularity is beneficial for more complex femoral defects.

Clinical outcomes and survival rate of cementless modular distal fixation femoral stem for revision hip arthroplasty: A minimum 6-year follow-up

PURPOSE

Revision hip arthroplasty is a very challenging procedure. Use of a modular distal fixation stem is one of the available options for revision arthroplasty in patients with proximal femoral bone deficiency. The purpose of this study was to evaluate mid- to long-term outcomes of cementless modular distal fixation femoral stem implantation in revision hip surgery.

METHODS

Clinical and radiological findings, complications, and stem survival rate were analyzed for 46 patients (48 hips) who underwent revision hip arthroplasty using a cementless modular distal fixation femoral stem. The mean patient age was 58.8 years (range 31-82 years) and the mean follow-up period was 95 months (72-122 months). The preoperative diagnoses were aseptic loosening (36 hips), infection (4 hips), ceramic fracture (4 hips), and femoral periprosthetic fracture (4 hips).

RESULTS

The mean Harris hip score improved from 56.6 preoperatively to 88.2 postoperatively at the last follow-up. All hips showed stable osteointegration and firm fixation. Complications involved four hips (8.3%); there was one case each of periprosthetic fracture, delayed union of osteotomy site, femoral perforation, and infection. One stem re-revision was performed for deep infection of the femoral side. The Kaplan-Meier survival rate was 97.6% at the final follow-up.

CONCLUSION

Revision hip arthroplasty using a cementless modular distal fixation femoral stem showed satisfactory initial firm fixation and mid- to long-term survival rate. Complications can be minimized by careful surgical planning and meticulous procedure.

Mid-term outcomes of titanium modular neck femoral stems in revision total hip arthroplasty

Background

Modular stems have been widely studied as they allow intraoperative adjustments (offset, anteversion, limb length) to better restore hip biomechanics. Many authors reported outcomes of revision total hip arthroplasty (THA) using modular stems with metaphyseal-diaphyseal junctions, however, little is known about modular neck femoral stems (MNFS) with metaphyseal-epiphyseal junctions. We therefore aimed to report outcomes and implant survival of a MNFS in a consecutive series of revision THA at a minimum follow-up of 5 years.

Methods

We reviewed a consecutive series of 28 revision THAs performed between February 2010 and March 2012 using an uncemented MNFS. The final study cohort included 25 patients living with their original components, at a mean follow-up of 68.4±7.4 months and aged 67.7±11.6 years at index operation.

Results

The Harris Hip Score (HHS) improved from 39.1±19.2 pre-operatively to 78.1±18.3 post-operatively, and the Postel Merle d'Aubigné score (PMA) improved from 9.8±3.0 pre-operatively to 14.8±2.8 post-operatively. The postoperative limb length discrepancy (LLD) was >10 mm in 18% of the hips. There were no significant differences of femoral offset and neck shaft angle (NSA) between operated and contralateral hips. Two hips (8.0%) showed new periprosthetic radiolucent lines. Periprosthetic fractures (PPF) occurred in 3 hips (12%). No subluxations, dislocations or implant breakages were reported. One revision (3.6%) was performed with retrieval of the revision stem for infection. The Kaplan-Meier (KM) survival at 5 years, using stem revision as endpoint, was 96.0%.

Conclusions

The Optimal^® MNFS provided a satisfactory survival and clinical outcomes at 5 years, with no noticeable adverse effects resulting from the additional modular junction.

Revision Hip Arthroplasty Using a Modular, Cementless Femoral Stem: Intermediate-Term Follow-Up

BACKGROUND

Modular femoral stem provides flexibility in femoral reconstruction, ensuring improved "fit and fill". However, there are risks of junction failure and corrosion, as well as cost concerns in the use of modular femoral stems.

METHODS

We reviewed prospectively-gathered clinical and radiographic data on revision total hip arthroplasties (THAs) performed from 2001-2007 using modular, cementless femoral component performed by the 2 senior authors. Patients with a minimum follow-up of 7 years were included in this study.

RESULTS

Sixty-four patients (68 hips) with a median age of 68 ± 14 years (range 40-92 years) at revision THA were included. The median follow-up was 11.0 ± 1.8 years (range 7-14). Harris hip score, femoral stem subsidence, and stem osseointegration were recorded. The Harris hip score improved from an average of 38.1-80.1 (P < .01). Five hips had one or more dislocations. Seven patients underwent reoperations, 3 of which did not involve the stem. Four stems required revision because of infection, recurrent dislocation, or suboptimal implant position. Survival rates for any reasons and revision for femoral stems were 90% and 94%, respectively, at the most recent follow-up. Four stems subsided more than 5 mm, but established stable osseointegration thereafter. Seven nonloose stems (10.2%) demonstrated radiolucent lines in Gruen zones 1 and 7. No complications regarding the modular junction were encountered.

CONCLUSION

Modular, cementless, extensively porous-coated femoral components have demonstrated intermediate-term clinical and radiographic success. Initial distal intramedullary fixation ensures stability, and proximal modularity further maximizes fit and fill.

Midterm results following uncemented, modular, fully porous coated stem used in revision total hip arthroplasty: Comparison of two stem systems

BACKGROUND

Aim of this study was to evaluate stem subsidence and survivorship of implant following implantation of Revitan (Zimmer) and MP (Waldemar Link) stems.

METHODS

Retrospective case series with clinical and radiological follow-up of 1-10 years.

RESULTS

47 Revitan and 57 MP stems were analyzed. In 12 cases there was subsidence of the stem present. Two Revitan stems and one MP stem were revised as a result of subsidence. Failure rate was 4.3% for Revitan, 1.8% for MP stem and difference was not statistically significant.

CONCLUSION

There is no significant difference in subsidence or survivorship between Revitan and MP stems.

Management of femoral bone loss in revision total hip arthroplasty

Femoral bone loss is frequently encountered during revision total hip arthroplasty. The quality and quantity of remaining bone helps determine the best method for reconstruction. Extensively porous-coated cylindrical stems or titanium fluted tapered devices that achieve fixation in the diaphysis have both demonstrated excellent long-term survivorship. Titanium fluted tapered stems with a modular proximal body allow for more accurate leg length, offset, and version adjustments independent of the distal stem which may optimise hip biomechanics. Intraoperative fractures are more common with cylindrical stems and subsidence with tapered stems, particularly monoblock designs and in both dislocation continues to be one of the most common postoperative complications. In salvage situations in which an ectatic femoral canal is unable to support an uncemented device, impaction bone grafting, allograft-prosthetic composite, or a segmental proximal femoral replacement may be required.

Is There a Benefit to Modularity in 'Simpler' Femoral Revisions?

BACKGROUND

Modular revision femoral components allow the surgeon to make more precise intraoperative adjustments in anteversion and sizing, which may afford lower dislocation rates and improved osseointegration, but may not offer distinct advantages when compared with less expensive monoblock revision stems.

QUESTIONS/PURPOSES

We compared modular and monoblock femoral components for revision of Paprosky Type I to IIIA femoral defects to determine (1) survivorship of the stems; and (2) complications denoted as intraoperative fracture, dislocation, or failure of osseointegration.

METHODS

Between 2004 and 2010, participating surgeons at three centers revised 416 total hip arthroplasties (THAs) with Paprosky Type I to IIIA femoral defects. Of those with minimum 2-year followup (343 THAs, mean followup 51 ± 13 months), 150 (44%) were treated with modular stems and 193 (56%) were treated with monoblock, cylindrical, fully porous-coated stems. During this time, modular stems were generally chosen when there was remodeling of the proximal femur into retroversion and/or larger canal diameters (usually > 18 mm). A total of 27 patients died (6%) with stems intact before 2 years, 46 THAs (13%) were lost to followup before 2 years for reasons other than death, and there was no differential loss to followup between the study groups. The modular stems included 101 with a cylindrical distal geometry (67%) and 49 with a tapered geometry (33%). Mean age (64 versus 68 years), percentage of women (53% versus 47%), and body mass index (31 versus 30 kg/m(2)) were not different between the two cohorts, whereas there was trend toward a slightly greater case complexity in the modular group (55% versus 65% Type 3a femoral defects, p = 0.06). Kaplan-Meier survivorship was calculated for the endpoint of aseptic revision. Proportions of complications in each cohort (dislocation, intraoperative fracture, and failure of osseointegration) were compared.

RESULTS

Femoral component rerevision for any reason (including infection) was greater (OR, 2.01; 95% CI, 1.63-2.57; p = 0.03) in the monoblock group (27 of 193 [14%]) compared with the modular cohort (10 of 150 [7%]). Femoral component survival free from aseptic rerevision was greater in the modular group with 91% survival (95% CI, 89%-95%) at 9 years compared with 86% survival (95% CI, 83%-88%) for the monoblock group in the same timeframe. There was no difference in the proportion of mechanically relevant aseptic complications (30 of 193 [16%] in the monoblock group versus 34 of 150 [23%] in the modular group, p = 0.10; OR, 1.47; 95% CI, 0.86-2.53). There were more intraoperative fractures in the modular group (17 of 150 [11%] versus nine of 193 [5%]; OR, 2.2; 95% CI, 1.68-2.73; p = 0.02). There were no differences in the proportions of dislocation (13 of 193 [7%] monoblock versus 14 of 150 [9%] modular; OR, 0.96; 95% CI, 0.67-1.16; p = 0.48) or failure of osseointegration (eight of 193 [4%] monoblock versus three of 150 [2%] modular; OR, 1.92; 95% CI, 0.88-2.84; p = 0.19) between the two groups with the number of hips available for study.

CONCLUSIONS

Although rerevisions were less common in patients treated with modular stems, aseptic complications such as intraoperative fractures were more common in that group, and the sample was too small to evaluate corrosion-related or fatigue concerns associated with modularity. We cannot therefore conclude from this that one design is superior to the other. Larger studies and pooled analyses will need to be performed to answer this question, but we believe modularity should be avoided in more straightforward cases if possible.

LEVEL OF EVIDENCE

Level III, therapeutic study.

REVISION TOTAL HIP ARTHROPLASTY USING A MODULAR CEMENTLESS DISTAL FIXATION PROSTHESIS: THE ZMR(®) HIP SYSTEM. CLINICAL AND RADIOGRAPHIC ANALYSIS OF 30 CASES

Objective: To evaluate the clinical and radiographic results from 30 cases of revision of total hip arthroplasty using a modular cementless distal fixation prosthesis: the ZMR^® Hip System. Method: Between July 2005 and December 2008, 30 operations were performed, on 14 men and 14 women. Two male patients had bilateral surgery. The mean age was 59.2 years (29-81 years), with a mean follow-up of 24 months. The Paprosky classification was used for periprosthetic bone loss, and the Harris Hip Score (HHS) was used to evaluate clinical results. On radiographs, distal migration of the femoral stem was defined in accordance with Sporer. Proximal bone remodeling was classified using the Callaghan criteria. Results: The mean preoperative HHS was 39, and there was a significant increase to 93 points in the final evaluation, which indicated excellent clinical results. No femoral stem migration greater than 5 mm (Sporer) was observed on radiographs, thus suggesting that all the femoral prostheses presented osseointegration and remained stable from the time of the surgery until the final evaluation. The proximal femoral remodeling was either type B or type C in 29 hips, according to Callaghan. Seven patients had complications, but without interfering with osseointegration of the femoral components. Conclusion: Our results from revision of total hip arthroplasty using the ZMR^® Hip System were extremely encouraging, and all the components became osseointegrated and remained fixed at the time of the final evaluation.

Outcomes of Mixed Femoral Fixation Technique Using Both Cement and Ingrowth in Revision Total Hip Arthroplasty: Minimum 2-Year Follow-up

The use of a modular femoral stem in revision total hip arthroplasty (THA) has been increasing recently. However, complications such as subsidence, dislocation and stem fracture are still noted, especially in hips with high grade femoral deficiency. We retrospectively studied a consecutive 41 hips (40 patients) that underwent revision THA with allograft reconstruction of the proximal femur in conjunction with hybrid fixation (proximally cemented and distally press-fit) of a modular femoral component. At a mean follow-up of 5.2 years (2 to 8 years), no hips sustained dislocation, subsidence or fracture of the stem in the follow-up period. We provided evidence that this technique may be a good alternative in the management of proximal femoral bone loss during revision THA.

Mid-term results of previously cemented hip arthroplasties revised with uncemented modular femoral components: a retrospective study

BACKGROUND

We evaluated the mid-term results of previously cemented hip arthroplasties revised with uncemented modular femoral components.

METHODS

The study included 40 patients (36 females (90 %) and 4 males (10 %), mean age 67.6 years, range 39-87 years) who underwent revision of a previously cemented hip prosthesis with an uncemented modular femoral stem between 2005 and 2009. The indications for revision were femoral aseptic loosening in 38 (95 %) cases and acetabular protrusion in 2 (5 %). According to the Paprosky classification, the femoral defect was type 1 in 10 (25 %) patients, type 2 in 16 (40 %), type 3a in 11 (27.5 %), type 3b in 2 (5 %) and type 4 in 1 (2.5 %). The Harris hip score was used for the clinical evaluation. Femoral vertical subsidence, the cortical index and femoral stem stability were assessed radiologically. The mean follow-up period was 84 months (range 61-95 months).

RESULTS

The mean Harris hip score was 41.4 (range 35.4-44.4) preoperatively and 80.9 (range 65.6-98.3) at the final follow-up examination (p < 0.05). Mean vertical subsidence was 5.7 mm (range 2.5-10.5 mm) in seven (17.5 %) patients. Stable bone fixation was observed in 38 (95 %) patients, fibrous stable fixation in 2 (5 %) and no instability in any patient. Radiographs taken during the early postoperative period revealed that the cortical index was a mean of 1.34 (range 1.11-1.73) and a mean of 1.55 on the final follow-up radiographic examinations (range 1.16-1.91) (p < 0.01).

CONCLUSIONS

Satisfactory results were achieved using uncemented modular femoral components during revision of previously cemented femoral components. Many modular femoral stems provide primary stability by filling femoral bone losses and help determine stem length, offset and anteversion.

Revision hip arthroplasty using a modular revision hip system in cases of severe bone loss

We sought to identify outcomes of the Restoration Modular Hip System in cases of severe femoral bone stock deficiency. We performed a retrospective review of 55 revTHAs with a mean follow-up of 32 months (24-60 months). Outcomes included the WOMAC and HHS. Preoperative bone loss was categorized as Paprosky 3A (n = 13), 3B (n = 14), and 4 (n = 17). Periprosthetic fractures were classified as Vancouver B2 (n = 6) and B3 (n = 5). 53 of 55 stems were in situ at time of final review. WOMAC improved from 46 ± 18 to 70 ± 22 and HHS improved from 47 ± 15 to 78 ± 15. Complications were identified in 9 patients, which included dislocation (3), subsidence (2), infection (2), and periprosthetic fracture (2). In cases of significant proximal femoral bone deficiency, this stem demonstrated improvement in clinical outcomes with good results at short-term follow up.

Revision hip arthroplasty with a modular cementless stem: mid-term follow up

Despite the increasing volume of revision total hip arthroplasty (THA) being performed in the United States, there are few studies reporting mid-term clinical and radiographic outcomes of modular fully porous-coated femoral stems. We retrospectively studied a consecutive series of patients who underwent revision THA with a modular extensively porous-coated femoral component at a single institution and by a single surgeon. The final study group included 54 hips (52 patients) followed for an average of 84 months. Ten-year survival rates with revision for any reason and revision for femoral loosening as endpoints were 94% and 100%, respectively. No complications regarding the modular junction were encountered. Of the 50 hips with adequate radiographs, all showed proximal ingrowth and 42 (84%) had both proximal and distal ingrowth. The modular, fully porous-coated femoral stem studied demonstrated excellent survivorship and bone ingrowth at mid-term follow up.

Three to seven year follow-up of a tapered modular femoral prosthesis in revision total hip arthroplasty

PURPOSE

Modular femoral prostheses can provide independent distal fixation and intraoperative flexibility and are being used increasingly, especially in patients with proximal femoral bone defects. This retrospective clinical study evaluated whether modular prostheses were effective and reliable implants for femoral revision.

METHOD

This case series consisted of 58 patients who underwent hip revision with a tapered modular femoral prosthesis at our institution between 2004 and 2008. Mean patient age at surgery was 64 years (range 18-86 years). Femoral bone defects before revision surgery were evaluated using the Paprosky classification. All patients were followed for a minimum of 3 years (mean 4.3 years, range 3-7 years) with clinical and radiographic evaluation. Re-revisions and complications were also recorded.

RESULTS

Two stems required re-revision, one each for recurrent deep infection and periprosthetic fracture. At last follow-up, the Harris Hip Score and Visual Analog Pain Scores had improved significantly, the median radiographic stem migration was 1.6 mm, leg length discrepancy was corrected in 64 % of the patients and osseointegration occurred in 90 %. Complications included intraoperative fracture in 10 (17 %) patients and hip dislocation in 2 (3 %).

CONCLUSION

Modular femoral components can improve hip function, provide distal fixation, equalize leg length, and result in fewer complications when used to revise failed femoral components.

High survival of modular tapered stems for proximal femoral bone defects at 5 to 10 years followup

BACKGROUND

Currently, the two most commonly used options for the revision of femoral components in North America are: cylindrical, nonmodular, cobalt-chromium stems and tapered, fluted, modular, titanium (TFMT) stems. Previous reports have cited high failure rates with cylindrical cobalt chrome stems in large femoral defects but the longer term survival of the fluted stems is unknown.

QUESTIONS/PURPOSES

We examined the 5- to 10-year survival of TFMT stems implanted for severe femoral defects.

METHODS

We reviewed all 65 patients with severe proximal bone defects revised with the TMFT stem between January 2000 and 2006. Ten were lost to followup and seven were dead, leaving 48 patients for followup at 5 to 10 years (mean, 84 months; range, 60-120 months). All patients completed five quality-of-life (QOL) questionnaires. Radiographs were evaluated for loosening, subsidence, and preservation of proximal host bone stock.

RESULTS

Implant survivorship was 90%. No patient underwent revision for either subsidence or loosening. Subsidence occurred in seven patients (average, 12.3 mm) but all achieved secondary stability. Five patients underwent revision as a result of fracture of the stem and all had the original standard stem design, which has since been modified. All five implant fractures occurred at the modular stem junction. Mean QOL outcomes were: WOMAC = 81 (pain), Oxford = 75, SF-12 = 54 (mental) and 38 (physical), UCLA Activity = 4, and satisfaction overall = 73.

CONCLUSIONS

Midterm survivorship of modular titanium stems in large femoral defects is high; however, ongoing surveillance of stem junctional fatigue life is required.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Revision total hip arthroplasty using a modular femoral implant in Paprosky type III and IV femoral bone loss

The purpose of this study was to compare results of patients with Paprosky type I and II femoral defects vs type IIIA, IIIB, and IV defects in patients undergoing revision hip arthroplasty. There were 64 patients in the group with type I and II defects with an average age of 68 years. There were 52 patients with Paprosky type IIIA, IIIB, and IV defects with an average age of 67 years. There were 8 intraoperative fractures in the type III and IV group, whereas there were 9 in the type I and II group. There were no differences between the 2 groups with respect to subsidence, loosening, dislocation, infection, and medical complications. Survivorship for the whole group was 96.9% at 5 years. Modular femoral implants provide several intraoperative options to restore leg length, offset, and stability despite femoral defects. We did not realize a higher failure rate in patients with type III or IV defects.

Stem subsidence after total hip revision: 183 cases at 5.9 years follow-up

INTRODUCTION

Secondary subsidence of a revision femoral stem is often a negative predictive sign for successful osseointegration and perfect long-term stability.

MATERIALS AND METHODS

We performed a retrospective study in a series of 183 revision total hip replacements between 1996 and 2000 to evaluate the importance and risk factors of secondary subsidence with a cementless press-fit design femoral stem as well as this subsidence's consequences to osseointegration.

RESULTS

Secondary subsidence did not occur in 80 cases (53%), was between 0 and 4mm in 41 cases (27%); between 5 and 10mm in 17 cases (12%) and was greater than 10mm in 12 cases (8%). Mean subsidence of all patients was 3mm (0-30). There was a statistically significant negative correlation between subsidence and the quality of osseointegration (P=0.03). There was no significant relationship between component diameter and stem subsidence (P=0.9). The presence of preoperative bone deficiencies did not increase the risk of secondary subsidence (P=0.2).

CONCLUSION

In the case of revision with press-fit stems, the importance of secondary subsidence should not be overestimated, because it usually does not negatively affect satisfactory osseointegration.

Treatment of a well-fixed modular fully porous coated stem after fracture using a custom rescue sleeve

We report a novel technique for the treatment of a fractured fully porous-coated modular stem. The fracture of the stem occurred at the taper of the stem-body junction. In both cases, the stem was well-fixed distally making the reconstruction difficult. Previously, authors have reported the use of an extended trochanteric osteotomy or multiple cortical windows for removal of this type of prosthesis. The technique we describe uses a custom-made "rescue sleeve" that takes advantage of the distal ingrowth. The rescue sleeve is fitted onto the existing stem obviating the need for an extended trochanteric osteotomy. The rescue sleeve's geometry makes up for the loss in height and accepts the modular body components to give the surgeon the length options to optimize stability.

Revision total hip arthroplasty with a modular tapered stem

Femoral stem revision surgery with proximal bone loss may be treated with modular uncemented distal fixation stems. Early results of the ZMR tapered stems with relatively fewer cases were encouraging. In this prospective study, we evaluated the 2 to 10 years survivorship, associated complications and functional outcomes of 84 cases of femoral revision using the ZMR tapered stem. The indications for revision were aseptic loosening (50), periprosthetic fracture (12), infection (17), stem fracture (4) and instability (1). The mean follow-up was 46 months (range, 25-117). The Kaplan-Meier survival with femoral re-revision for any reason as an end-point was 92.7% (95% CI: 87.7%-97.7%). The mean Harris hip score improved from 37 (10-77) points before operation to 72 (41-96) points at last follow-up. The ZMR tapered stem has shown satisfactory results in 2 to 10 years followup in various femoral stem revision conditions.

A biomechanical assessment of modular and monoblock revision hip implants using FE analysis and strain gage measurements

Background

The bone loss associated with revision surgery or pathology has been the impetus for developing modular revision total hip prostheses. Few studies have assessed these modular implants quantitatively from a mechanical standpoint.

Methods

Three-dimensional finite element (FE) models were developed to mimic a hip implant alone (Construct A) and a hip implant-femur configuration (Construct B). Bonded contact was assumed for all interfaces to simulate long-term bony ongrowth and stability. The hip implants modeled were a Modular stem having two interlocking parts (Zimmer Modular Revision Hip System, Zimmer, Warsaw, IN, USA) and a Monoblock stem made from a single piece of material (Stryker Restoration HA Hip System, Stryker, Mahwah, NJ, USA). Axial loads of 700 and 2000 N were applied to Construct A and 2000 N to Construct B models. Stiffness, strain, and stress were computed. Mechanical tests using axial loads were used for Construct A to validate the FE model. Strain gages were placed along the medial and lateral side of the hip implants at 8 locations to measure axial strain distribution.

Results

There was approximately a 3% average difference between FE and experimental strains for Construct A at all locations for the Modular implant and in the proximal region for the Monoblock implant. FE results for Construct B showed that both implants carried the majority (Modular, 76%; Monoblock, 66%) of the 2000 N load relative to the femur. FE analysis and experiments demonstrated that the Modular implant was 3 to 4.5 times mechanically stiffer than the Monoblock due primarily to geometric differences.

Conclusions

This study provides mechanical characteristics of revision hip implants at sub-clinical axial loads as an initial predictor of potential failure.

Revision total hip arthroplasty with a porous-coated modular stem: 5 to 10 years follow-up

The ZMR porous stem is a modular cylindrical porous-coated femoral stem for revision THA. The objective of this study was to evaluate the clinical and radiographic outcomes of this stem at midterm followup. We prospectively reviewed 69 patients (72 femoral revisions) treated with the stem. The indication for revision was aseptic loosening in 61 (85%), periprosthetic fractures in five (7%), infection in three (4%), dislocation in two (3%), and fractured stem in one (1%). Minimum followup was 60 months (mean, 85 months; range, 60-114 months). The survival rate with revision for any reason as an end point was 93.8%. Mean preoperative Harris hip score was 39 points, and mean Harris hip score at last followup was 72 points. Four (5.5%) stems required rerevision, two (2.8%) for loosening, one (1.4%) for fracture at the modular junction, and one (1.4%) for infection. Subsidence occurred in eight (11%) patients, in the range of 5 to 25 mm. Two (2.89%) of the stems that subsided were symptomatic and progressive. The ZMR porous stem is a versatile system that offers a reliable fixation and an off-the-shelf solution for a multitude of femoral reconstruction challenges.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Femoral revision hip arthroplasty: a comparison of two stem designs

For various reasons the tapered, fluted, modular titanium (TFMT) stem has become our component of choice over cylindrical, nonmodular cobalt chrome (CNCC) components for THA revision. We therefore asked whether the TFMT femoral components better achieved three important goals of revision arthroplasty than CNCC stems: (1) improving quality of life; (2) avoiding complications; and (3) preserving or restoring femoral bone stock. We compared patients undergoing femoral component revision hip arthroplasty with either a CNCC (N = 105) component or a TFMT (N = 95) component to determine if the increased use of TFMT components is justified. We retrospectively reviewed all patients undergoing revision total hip arthroplasty between January 2000 and March 2006. All eligible patients completed outcome questionnaires (WOMAC, SF-12, Oxford-12, UCLA Activity Score, and Satisfaction Scores). Radiographs were evaluated for loosening and preservation or restoration of the proximal femur host bone. The TFMT and CNCC cohorts were comparable with respect to age, gender, diagnosis, and comorbidities. The TFMT cohort had worse preoperative bone defects (65% Paprosky 3B and 4). The TFMT cohort had higher outcome scores (WOMAC pain, WOMAC stiffness, Oxford-12, and Satisfaction), fewer intraoperative fractures, and better restoration of the proximal femur host bone. Our data suggest the TFMT stem provided improved clinical outcomes (improved quality of life, decreased complications, and preservation of bone stock) than the CNCC stem.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Stem modularity alone is not effective in reducing dislocation rate in hip revision surgery

Background

Dislocation is a serious complication following total hip arthroplasty (THA). Femoral revision using monoblock components has been associated with high incidence of subsidence and dislocation. Advantages of modular stems in THA have long been debated. The aim of this retrospective study is to assess the capability of an uncemented modular stem in decreasing the incidence of early dislocation subsequent to revision THA.

Materials and methods

We evaluated the dislocation rate during the first 2 years following revision surgery in two groups of patients who were treated by implantation of a cementless tapered femoral prosthesis; a standard-modularity stem (Wagner SL) and an increased-modularity stem (Profemur R) were used, respectively, in 66 hips (group I, 64 patients) and 102 hips (group II, 97 patients). Group I consisted of 47 females and 17 males with average age of 66 years (range 29–84 years). Group II included 60 females and 37 males with average age of 70 years (range 48–89 years).

Results

Dislocation occurred in six hips (9.1%) of group I and in seven hips (6.8%) of group II (P = 0.401). Dislocations were observed early in both groups, except one hip in group II that dislocated 434 days postoperatively and required surgical reduction. All other dislocations were treated by closed reduction. No recurrence was observed.

Conclusions

The use of an increased-modularity revision stem alone did not prove to be effective in reducing the risk of postoperative dislocation.