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

Modular versus monoblock stem in revision total hip arthroplasty: a systematic review and meta-analysis

Background

Total hip arthroplasty (THA) is estimated to grow in the following decades with a consequent increase of THA revisions (rTHA). This systematic review and meta-analysis aims to compare modular and monoblock stem in rTHA surgery, focusing on clinical and radiological outcomes and complication rates.

Methods

A literature search was performed using the following search strategy: ((Modular stem) OR (monolithic stem)) AND (hip review) on PubMed, Scopus, and Cochrane. Randomized controlled trials (RCTs) and observational studies (OS) compared clinical and radiological outcomes, and complication rates for monoblock and modular revision femoral stem were included. The risk of bias was assessed through the Methodological Index for Non-Randomized Studies (MINORS) score. The Review Manager (RevMan) software was used for the meta-analysis. The rate of complications was assessed using odds ratio (OR) with 95% confidence intervals (CIs).

Results

The authors included 11 OS and one RCT with 3,671 participants (mean age: 68.4 years old). The mean follow-up was 46.9 months. There was no prevalence of subsidence for one type of stem. Mean subsidence was from 0.92 to 10 mm for modular stem and from 1 to 15 mm for monoblock stem. Postoperative Harris Hip Score (HHS) showed better results with modular stems without statistical significance [mean difference (MD) =1.32; 95% CI: -1.62 to 4.27; P=0.38]. No statistically significant difference was found for dislocations (OR =2.48; 95% CI: 0.67 to 9.14; P=0.17), infections (OR =1.07; 95% CI: 0.51 to 2.23; P=0.86), intraoperative fractures (OR =1.62; 95% CI: 0.42 to 6.21; P=0.48), and postoperative fractures (OR =1.60; 95% CI: 0.55 to 4.64; P=0.39).

Conclusions

Modular and monoblock stems show comparable and satisfactory clinical and radiological outcomes for rTHA. Both stems are valid and effective options for managing femoral bone deficit in hip revision surgery. The main limitation of this study is the small number and low quality of enclosed studies that compared the two stems. Moreover, the modular stem is usually used for more complex cases with lower quality femoral bone stock.

Long-Term Outcomes of Revision Total Hip Arthroplasty Using a Tapered and Fluted Modular Stem: A Mean Follow-Up of 16 Years

BACKGROUND

Tapered modular stems are increasingly used in revision total hip arthroplasty (THA) with deficient femoral bone stock. This study aimed to report the long-term outcomes of revision THA using a tapered and fluted modular stem.

METHODS

Between December 1998 and February 2006, 113 revision THAs (110 patients) were performed with a tapered and fluted modular stem at a single institution. Hip radiographs were used to identify stem subsidence, stability, and femoral radiolucency. Final outcomes were assessed in 72 hips (70 patients), with a minimum follow-up of 10 years.

RESULTS

The mean follow-up duration was 16 years (range, 10-23). At the final evaluation, the Harris Hip Score improved from a mean of 41 points (range, 10-72) preoperatively to 83 points (range, 56-100) (P < .001). Six femoral re-revisions were performed for the following reasons: 1 aseptic loosening, 2 stem fractures, and 3 infections. One stem fracture occurred at the modular junction after 14 years, and the other at a more distal location after 15 years. Stem subsidence was >5 mm in 6 hips (9.1%), but secondary stability was achieved in all stems. Osseointegration was observed in 63 (95.5%) hips. Stem survivorship was 91.1% with an end point of any re-revision and 94.6% for aseptic re-revision.

CONCLUSION

A tapered and fluted modular stem demonstrated excellent implant survivorship with reliable bony fixation at a mean follow-up of 16 years. This type of stem can be a durable option for revision THA in patients who have femoral defects.

Modular tapered conical revision stem in hip revision surgery: mid- term results

Background

The aim of this paper is to evaluate the clinical and radiological outcomes of a fluted tapered modular distal-fixation stem at medium to long-term follow-up. The hypothesis of this investigation was to verify if the use of this implant design may have provided potential advantages in femoral revisions and post-traumatic instances where the restoration of the anatomy was the prime concern.

Methods

We retrospectively reviewed 62 cases of femoral revision surgeries, performed in Paprosky type IIIA and IIIB bone defects between January 2001 and December 2011 with a mean follow-up of 8.5 ± 1.5 years (range 5.1–15.9 years) where a modular fluted stem was used. The clinical assessment was performed with the Harris Hip Score (HHS), and the radiographic evaluation was carried in order to assess the stability of the femoral component. Intra-operative and postoperative complications were recorded, and the rates of complications and revisions for any cause were determined.

Results

Mean HHS improved 35.4 points from the preoperative assessment. Radiographic evaluation showed a stable stem anchorage in 90.3% of the cases at the last follow-up. Five (8%) implants required additional surgery. Neither breakage of the stem nor loosening of the taper junction were recorded. Kaplan-Meier survivorship was 89.4% (CI: 88.8–90%) for any complication and 92.3% (CI: 91.8–92.7%) according to revision for any causes at 81 months follow-up.

Conclusions

Our findings suggest that this stem design is a reliable option in cases of complex femoral bone defects, as well as in cases with high functional deficiencies, with promising survivorship.

Long-term outcomes of Wagner self-locking stem with bone allograft for Paprosky type II and III bone defects in revision total hip arthroplasty: A mean 15.7-year follow-up

PURPOSE

Massive bone defects represent a challenge in revision total hip arthroplasty (THA). Wagner self-locking (SL) stem is a favorable option for this technique; however, its long-term outcomes with bone allograft have rarely been reported. The purpose of this study was to investigate the long-term outcomes of this stem with bone allograft for Paprosky type II and III bone defects in revision THA.

METHODS

A total of 38 patients (40 hips) who underwent revision THA with the Wagner SL stem were retrospectively reviewed. Bone allograft was placed in every patient. Clinical outcomes were determined using the Japanese Orthopedic Association's hip scoring system (JOA hip score). Stem subsidence, stem fixation, and remodeling of the grafted bone were assessed radiographically. The survival rate of the stem was assessed by Kaplan-Meier survival analysis.

RESULTS

The mean JOA hip score at the latest follow-up was 75.3 points. Stem subsidence of ≥10 mm was observed in four hips (10.0%). Moreover, 67.5% (27/40) of hips were stable, and 27.5% (11/40) had fibrous fixation. Bone restoration was observed in 25 hips (62.5%). At a mean follow-up of 15.7 years, the cumulative stem survival rates were 96.6%and 91.7% with "stem re-revision for loosening" and "stem re-revision for any reason" as the end points, respectively.

CONCLUSION

The Wagner SL stem with bone allograft for proximal femoral bone defects in revision THA is a clinically beneficial 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.

Exchangeable Femoral Neck (Dual-Modular) THA Prostheses Have Poorer Survivorship Than Other Designs: A Nationwide Cohort of 324,108 Patients

BACKGROUND

Exchangeable neck stems, defined as those with a dual taper (that is, a modular junction between the femoral head and the femoral neck and an additional junction between the neck and the stem body), were introduced in THA to improve restoration of joint biomechanics (restoring anteversion, offset, and limb length) and reduce the risk of dislocation. However exchangeable necks have been reported to result in adverse effects such as stem fractures and acute local tissue reaction. Whether they result in a net improvement to or impairment of reconstructive survivorship remains controversial.

QUESTIONS/PURPOSES

(1) To compare the prosthetic survivorship and all-cause revision risk of exchangeable femoral neck THAs versus fixed neck THAs, taking known prosthetic revision risk factors into account; and (2) to compare the cause-specific revision risk of exchangeable femoral neck THAs versus fixed neck THAs, adjusting for known prosthetic risk factors.

METHODS

Using French national health-insurance databases, we identified all French patients older than 40 years who underwent primary THA from 2009 through 2012. To ensure accuracy of the data, we considered only beneficiaries of the general insurance scheme (approximately 77% of the population). Characteristics of the prosthesis and the patients receiving an exchangeable femoral neck THA were compared with those receiving a fixed femoral neck THA (defined as femoral stem with only the head being exchangeable). Revision was the event of interest. Followup started on the date the THA was performed, until the patient experienced revision, died, was lost to followup, or until the followup period ended (December 31, 2014), whichever came first. Competing risk THA survivorship was calculated and compared (purpose 1), as were cause-specific Cox regression models (purpose 2). The study cohort included 324,108 individuals with a mean age of 77 years. A total of 24% underwent THA for acute trauma, and 3% of the group received an exchangeable neck THA. During the median 45-month followup (mean, 42 months; minimum, 1 day; maximum, 6 years), 11,968 individuals underwent prosthetic revision.

RESULTS

The cumulative revision incidence was 6.5% (95% CI, 5.8%-7.3%) for exchangeable neck THAs versus 4.7% (95% CI, 4.6%-4.8%) for fixed neck THAs (p < 0.001). After controlling for potential confounding variables including age, sex, comorbidities, indication for THA, cementation, bearing surface, and the characteristics of the center where the implantation was performed, we found that the exchangeable femoral neck THA was associated with an increased hazard ratio (HR) of revision of 1.26 (95% CI, 1.14-1.38; p < 0.001) compared with the fixed neck THA. When dealing with cause-specific revision, exchangeable neck THAs had a higher incidence of revision for implant failure or periprosthetic fracture, and for mechanical complications; adjusted HRs were, respectively, 1.68 (95% CI, 1.24-2.27; p < 0.001) and 1.27 (95% CI, 1.13-1.43; p < 0.001), for exchangeable neck THAs compared with fixed ones.

CONCLUSIONS

Exchangeable neck THAs had poorer survivorship independent of other prosthetic revision risk factors. Accordingly, expected anatomic and functional benefits should be carefully assessed before choosing this design.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Comparison of Clinical Efficacy Between Modular Cementless Stem Prostheses and Coated Cementless Long-Stem Prostheses on Bone Defect in Hip Revision Arthroplasty

Background

The aim of this study was to investigate and compare the clinical efficacy of modular cementless stem and coated cementless long-stem prostheses in hip revision arthroplasty.

Material/Methods

Sixty-five patients with complete hip revision surgery data during January 2005 to March 2015 were selected from the People’s Hospital of Linyi City and randomly divided into a S-ROM group (implanted with cementless modular stem prostheses, n=32) and a SLR-PLUS group (implanted with cementless coated long-stem prostheses, n=33). Harris score was used to evaluate the hip function of the patients in order to measure the clinical efficacy of the prostheses in total hip arthroplasty. Anteroposterior pelvic radiographs and lateral pelvic radiographs were taken and each patient’s hip arthroplasty condition was recorded. Kaplan-Meier method was applied to compare the cumulative 5-year non-revision rate between the 2 prostheses and log-rank method was used to inspect the statistical data.

Results

The Harris scores of both the S-ROM group and the SLR-PLUS group were significantly higher at 12 months after the operation than those before the operation (both P<0.05). The Harris scores of the patients with type I/II bone defects in the S-ROM group were not significantly different from those of the same types in the SLR-PLUS group at all time points (all P>0.05), while the Harris scores of the patients with type IIIA/IIIB in the S-ROM group were both significantly higher than those of the same types in the SLR-PLUS group at 3 months, 6 months, and 12 months after the operation (all P<0.05). No significant difference was found in the cumulative 5-year non-revision rate between the type I/II patients in the S-ROM group (92.31%) and the patients of the same types in the SLR-PLUS group (85.71%) (P>0.05). However, the cumulative 5-year non-revision rate of the type IIIA/IIIB patients in the S-ROM group (89.47%) was significantly different from the patients of the same types in the SLR-PLUS group (42.11%) (P<0.05).

Conclusions

The modular stem prostheses in hip revision arthroplasty were clinically more effective in the treatment of type IIIA and IIIB bone defects than the coated long-stem prostheses according to the Harris score and the cumulative 5-year non-revision rate.

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.

Hospital cost of treating early dislocation following hip arthroplasty

Dislocation is a frequent and costly complication of hip arthroplasty. The purpose of this study was to assess the financial impact on the treating institution of this complication in patients with primary hemiarthroplasty (HA), total hip arthroplasty (THA) and revision surgery (RTHA). Between October 2001 and August 2009, 2014 consecutive hip arthroplasties were performed at our institution, of which 87 (18 HA, 44 THA and 25 RTHA) dislocated within 6 weeks of the primary operation. The average cost of treating implant dislocation by closed reduction, open reduction or revision was assessed and expressed as a percentage cost increase compared to an uncomplicated procedure. Of the 87 dislocated implants all needed one or more closed reductions and 52 eventually required revision surgery. An early dislocation increased the cost of HA, THA and RTHA by 472%, 342% and 352%, respectively.

Modularity of the femoral component in total hip arthroplasty

Modular femoral components have been developed to aid in recreating native femoral version, limb length, and offset in total hip arthroplasty. Use of modular implants results in cost savings, as well. Inventory can be reduced while allowing intraoperative flexibility and options. With modular implants, the femoral prosthesis can be built in situ, which is helpful in minimizing incision length and surgical dissection. However, additional modular junctions are associated with increased concern for component failure through taper fretting, fatigue fracture, and local corrosion, which may contribute to elevated serum metal ion levels. The recent trend toward using larger diameter femoral heads may impart higher loads and stress than were seen previously. Although modular components offer a plethora of intraoperative options in primary and revision total hip arthroplasty, the long-term effects of these additional junctions remains unknown.

Influence of prosthesis design and implantation technique on implant stresses after cementless revision THR

BACKGROUND

Femoral offset influences the forces at the hip and the implant stresses after revision THR. For extended bone defects, these forces may cause considerable bending moments within the implant, possibly leading to implant failure. This study investigates the influences of femoral anteversion and offset on stresses in the Wagner SL revision stem implant under varying extents of bone defect conditions.

METHODS

Wagner SL revision stems with standard (34 mm) and increased offset (44 mm) were virtually implanted in a model femur with bone defects of variable extent (Paprosky I to IIIb). Variations in surgical technique were simulated by implanting the stems each at 4° or 14° of anteversion. Muscle and joint contact forces were applied to the reconstruction and implant stresses were determined using finite element analyses.

RESULTS

Whilst increasing the implant's offset by 10 mm led to increased implant stresses (16.7% in peak tensile stresses), altering anteversion played a lesser role (5%). Generally, larger stresses were observed with reduced bone support: implant stresses increased by as much as 59% for a type IIIb defect. With increased offset, the maximum tensile stress was 225 MPa.

CONCLUSION

Although increased stresses were observed within the stem with larger offset and increased anteversion, these findings indicate that restoration of offset, key to restoring joint function, is unlikely to result in excessive implant stresses under routine activities if appropriate fixation can be achieved.