Mean 23-Year Outcomes of Total Hip Arthroplasty Using a Modular Femoral Stem With Metaphyseal Fixation Sleeve.

BACKGROUND: Although the modular sleeve concept for femoral implants has several advantages, studies reporting on greater than 20-year outcomes are limited. This study aimed to report the mean 23-year results of total hip arthroplasty (THA) using a modular stem with metaphyseal fixation sleeve. METHODS: This study reviewed primary THAs performed using a modular stem between October 1994 and April 1998. Of the 272 hips (221 patients) identified, 220 hips (177 patients) satisfying the minimum 20-year follow-up were included. The Harris Hip Score was used for clinical evaluation. Final hip radiographs were analyzed to evaluate the implant stability and the extent of femoral osteolysis. The mean follow-up duration was 23 years (range, 20 to 28). RESULTS: The mean Harris Hip Score improved from 38 points (range, 26 to 67) preoperatively to 90 points (range, 71 to 100) at the final follow-up (P < .001). Femoral osteolysis was observed in 146 hips (67.1%), but 145 were located proximal to the osseo-integrated sleeve. Overall, 4 femoral revisions were performed; 2 for chronic infection, one for aseptic loosening, and one for periprosthetic femoral fracture. Of the 19 (8.6%) periprosthetic femoral fractures, the most common type was Vancouver AG (13 hips). One (0.5%) asymptomatic distal stem fracture occurred, while no complications were identified at the stem-sleeve junction. Implant survivorship free of any femoral revision was 98.3% at 23 years. CONCLUSIONS: A THA using a modular stem with metaphyseal fixation sleeve demonstrated 98.3% stem survivorship with excellent clinical outcomes at a mean follow-up of 23 years in non-obese patients.

A Consecutive Series of Vancouver B2 Periprosthetic Femur Fractures Treated With Contemporary Monoblock Versus Modular Revision Stems: Clinical and Radiographic Outcomes.

BACKGROUND: Tapered fluted titanium (TFT) stems are the implant design of choice for managing Vancouver B2 periprosthetic femur fractures (PFFs), producing reliable results over the past few decades. The aim of this study was to compare the radiographic and clinical outcomes of Vancouver B2 PFFs treated with contemporary monoblock versus modular TFTs. METHODS: A consecutive series of 113 patients (72 women, 64%, mean age 70 years [range, 26 to 96]) who had a B2 PFF were treated with either a monoblock (n = 42) or modular (n = 71) TFT stem between 2008 and 2021. The mean body mass index was 30 ± 7. The mean follow-up was 2.9 years. A radiographic review was performed to assess leg length and offset restoration, endosteal cortical contact length, and stem subsidence. Kaplan-Meier analyses were used to determine survivorship without revision, reoperation, or dislocation. RESULTS: There was no difference in the restoration of leg length (0.3 ± 8.0 mm) or offset (2.8 ± 8.2 mm) between the monoblock and modular cohorts (P > .05). Mean endosteal cortical contact length (47.2 ± 26.6 versus 46.7 ± 2 6.4 mm, P = .89) and stem subsidence (2.7 ± 3.5 versus 2.4 ± 3.2 mm, P = .66) did not differ. No difference in patient-reported outcome measures (Hip Disability and Osteoarthritis Outcome Score-Joint Replacement; Veterans RAND 12 Item Health Survey Physical and Mental; visual analog score; and Lower Extremity Activity Scale) between the groups was observed. Survivorship at 2 years free from reoperation, revision, and dislocation was 90.4, 90.3, and 97.6%, respectively, for the monoblock cohort; and 84.0, 86.9, and 90.0%, respectively, for the modular cohort. CONCLUSIONS: No significant differences in radiographic or clinical outcomes were observed between patients treated with monoblock or modular TFTs in this large series of B2 PFFs.

Risk factors for femoral stem fracture following total hip arthroplasty: a systematic review and meta analysis.

BACKGROUND: Femoral stem fracture following total hip arthroplasty (THA) is an infrequent but nevertheless devastating complication, with an increasing worldwide prevalence as demand for primary THA continues to increase. The aim of this study was to perform a systematic review and meta-analysis of risk factors for femoral stem fracture to help identify at risk patients. METHODS: A systematic search was conducted on EMBASE, MEDLINE and AMED to identify relevant studies. Data regarding study design, source, population, intervention, and outcomes was collated. Data extraction was performed on a custom form generated using Cochrane recommended methodology and analysis of risk factors performed including odds ratios (ORs) with 95% confidence intervals (CIs). RESULTS: A total of 15 studies reporting a total of 402 stem fractures in 49 723 THAs were identified. The median time from index procedure to stem fracture was 68 months (IQR 42.5-118) whilst mean age at index surgery was 61.8 years (SD 6.9). Male gender (OR = 3.27, 95% CI = 2.59-4.13, p < 0.001), patient weight above 80 kg (OR = 3.55, 95% CI = 2.88-4.37, p < 0.001), age under 63 years (OR = 1.22, 95% CI = 1.01-1.49, p < 0.001), varus stem alignment (OR = 5.77, 95% CI = 3.83-8.7, p < 0.001), use of modular implants (OR = 1.95, 95% CI = 1.56-2.44, p < 0.01) and undergoing revision arthroplasty (OR = 3.33, 95% CI = 2.70-4.1, p < 0.001) were significant risk factors for prosthetic stem fracture. A risk window of 15 years post-surgery was identified. CONCLUSIONS: This review concludes that patient weight, younger age, male sex, varus stem alignment, revision arthroplasty and use of modular stems are significant risk factors for femoral stem fracture. Modifying these risk factors where possible may help reduce incidence of femoral stem fracture in at risk patients.

Excellent Survival Rate of Cemented Modular Stems in One-Stage Revision for Periprosthetic Hip Infections With Massive Femoral Bone Loss: A Retrospective Single-Center Analysis of 150 Cases.

BACKGROUND: With the increasing incidence of total hip arthroplasty (THA), there is also an expected concurrent increase in revision THA (rTHA), which is known to have a high complication and re-revision rate. In the setting of infection, radical debridement is essential and options for femoral bone loss are limited. One viable solution is cemented modular stems, but limited evidence exists on their use in septic revision. This study aimed to analyze survival and complication related to the use of cemented modular stems in one-stage septic rTHA with severe femoral bone loss. METHODS: The institutional database of patients who underwent rTHA for septic one-stage revision with cemented modular stems was reviewed. Exclusion criteria were patients aged less than 18 years and nonseptic or 2 stage revisions. Outcomes measured were complication, re-infection, re-operation, and survivorship of the implant. A total of 150 patients were included. The mean age was 68 years (range, 30 to 91), and the mean follow-up was 105 months (range, 1 to 150). RESULTS: Treatment was considered successful in 81.3% of cases. Patients who underwent multiple prior surgeries demonstrated a lower rate of treatment success (P < .001). The main cause of failure was re-infection (11 of 28). Among cases failed for aseptic reasons (17 of 28), loosening of the cemented modular stem was the cause of re-revision in 2 patients (1.3%). CONCLUSIONS: The use of modular cemented stems is a viable option in case of septic one-stage rTHA associated with severe femoral bone loss. However, surgeons and patients should be aware that this treatment is still characterized by a high rate of complications, which may lead to further surgeries. LEVEL OF EVIDENCE: III.

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.

Total hip arthroplasty with femoral shortening osteotomy using polished cemented stem vs. modular cementless stem in patients with Crowe type IV developmental dysplasia of the hip.

INTRODUCTION: There is still little information regarding the advantages of a using a polished tapered stem for Crowe Type IV developmental dysplasia of the hip (DDH). This study aimed to investigate the mid-term clinical and radiological outcomes of primary total hip arthroplasty (THA) with femoral shortening osteotomy using modular and polished tapered stems and to compare the results between the modular and polished tapered stems. MATERIALS AND METHODS: This retrospective review included 32 patients (37 hips) with Crowe type IV DDH who underwent primary THA with femoral shortening osteotomy using a modular stem (cementless group, 14 hips) or a polished tapered stem (cement group, 23 hips) between 1996 and 2018. Clinical data and radiographic assessments were reviewed to analyze the differences between the two groups. RESULTS: The mean duration of patient follow-up of the cementless group (134.4 months) was longer than that of the cement group (75.5 months). There were no differences in clinical results, time of bone union, and survival rate between the two groups. However, the cementless group exhibited a higher ratio of intraoperative fracture and thinning of cortical bone including stress shielding, medullary changes, stem alignment changes, and osteolysis, compared to the cement group. CONCLUSIONS: The findings of this study suggest that THA with femoral shortening osteotomy using both cemented and modular stems can provide satisfactory results. However, considering the occurrence of intraoperative fracture and radiographic analysis in the current study, the cement stem may have an advantage for patients with bone fragility and deterioration in bone quality.

A Modified Modular Stem in Primary Total Hip Arthroplasty for Developmental Dysplasia of the Hip: Average 11-year Follow-Up in Cases With Previously Reported 3-year Clinical Results.

BACKGROUND: Modular stems require careful follow-up, especially after any design modification. This study investigated the mid- to long-term outcomes of total hip arthroplasty in patients with developmental dysplasia of the hip using the S-ROM-A stem, a modified S-ROM stem for Asians. METHODS: We previously reported short-term outcomes for all 220 dysplastic hips that underwent primary total hip arthroplasty with the S-ROM-A stem. Here, we followed the clinical and radiological outcomes of 201 of the 220 hips (91%) for a mean 11.4 years postoperatively. We also performed multivariate analysis to determine whether large anteversion angle adjustment was associated with increased osteolysis. RESULTS: The cumulative survival rate of the stem at 168 months postoperatively was 97.4%. Two hips underwent revision surgery, including 1 due to neck trunnionosis. Characteristic distal stem fracture occurred in 3 hips (1.5%). Most partial radiolucent lines observed around the sleeve early postoperatively disappeared by 7 years, postoperatively. Mild osteolysis occurred relatively frequently (20%), but a multivariate model adjusted for polyethylene type showed no significant association between the occurrence of osteolysis and anteversion adjustment of the modular stem (stem anteversion decreased ≤-20°, P = .829; stem anteversion increased ≥+20°, P = .619). CONCLUSION: Partial radiolucent lines early postoperatively do not affect long-term outcomes. The clinical benefits of actively adjusting the stem anteversion angle outweigh the mechanical risks. Mild osteolysis, stem fracture, and trunnionosis were relatively frequent complications. Analysis with longer follow-up and more cases are necessary to clearly determine if these complications are associated with the design modification.

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.

Revision Total Hip Arthroplasty Using the Modular Proximal Stem Modified for Asians: Medium-Term Clinical Results and Perioperative Complications.

BACKGROUND: This study aimed to examine the medium-term clinical and radiological outcomes of revision THA using the S-ROM-A stem, a modification of the S-ROM stem intended for Asians. METHODS: Femoral reconstruction using the S-ROM-A stem was performed in 126 hips that underwent revision THA. All patients were followed for perioperative complications. In addition, clinical and radiographic outcomes at a mean of 8 (range 5-14) years postoperatively were evaluated in 96 hips of 86 patients (76%). RESULTS: The most common perioperative complication was a femoral fracture, occurring in 16 hips (13%), including 11 intraoperative and 5 postoperative fractures. Dislocation occurred in five hips (4.0%), infection in three hips (2.4%), and trunnionosis in two hips (1.6%), including late complications. The total second stem revision was performed in two hips while stem only second revision preserving the bone ingrown sleeve was performed in four hips. With a second revision for aseptic loosening as the endpoint, the 13-year stem survival rate was 100%. Hip function as assessed by the Japanese Orthopedic Association score improved from a mean of 48 points preoperatively to 87 points 8 years postoperatively (P < .05). Radiological evaluation at the final follow-up showed that 95 hips (99%) achieved bone ingrowth fixation and one hip (1%) achieved fibrous stable status. CONCLUSION: Revision THA using the S-ROM-A stem resulted in good medium-term outcomes. Although modifications of the stem length and shape may be effective in preventing fractures in Asians with relatively small body sizes, attention should be paid to the occurrence of trunnionosis, which may be associated with the decreased taper size.

Long-Term Outcomes of Total Hip Arthroplasty With Transverse Subtrochanteric Shortening Osteotomy and Modular Stem in Crowe IV Developmental Dysplasia.

BACKGROUND: The reconstruction of high dislocation related to developmental dysplasia of the hip (DDH) remains challenging for joint surgeons. The aim of this study is to evaluate the rate of union, the revision rate, functional scores, and complications in patients with Crowe IV DDH treated with total hip arthroplasty, transverse subtrochanteric shortening osteotomy, and modular stem in an average 10-year follow-up. METHODS: Twenty-eight patients (33 hips) with Crowe IV DDH who were operated on between 2008 and 2013 were followed. All patients underwent uncemented total hip arthroplasty with transverse subtrochanteric shortening osteotomy and anatomical acetabular cup implantation. The mean age was 36.6 years, and the mean follow-up period was 121 months. Clinical and radiological outcomes were evaluated. RESULTS: The mean Harris Hip Score significantly improved from 47.0 preoperatively to 89.6 postoperatively. The mean limb length discrepancy was significantly reduced from 3.8 to 0.8 cm. The mean osteotomy union time was 6.8 months. At the mean follow-up of 121 months, there were 3 cases of postoperative dislocation, 2 cases of intraoperative fracture, and 1 case of posterior tibial venous thrombosis. No revision occurred, and no signs of component loosening or migration were observed at the last follow-up. CONCLUSION: Crowe IV DDH patients treated with transverse subtrochanteric shortening osteotomy, modular stem, and anatomic acetabular component insertion can have satisfactory and reliable 10-year clinical outcomes.

Modular stem in total hip arthroplasty for patients with trochanter valgus deformity: surgical technique and case series.

BACKGROUND: Trochanter valgus deformity (TVD) is a rare condition of total hip arthroplasty (THA). Femoral osteotomy could be required in correcting the deformity to implant femoral stem in severe TVD. In this study, we described one unpublished technique of reverse sleeve of S-ROM to get through the complex situation. This study aimed to summarize and evaluate its technical challenges, safety and effectiveness. METHODS: From January 2006 to December 2014, we enrolled patients whose sleeves were implanted towards the great trochanter in THA with TVD. Their demographics, perioperative and postoperative information were recorded. To explore its indication, we measured and analyzed the ratio of greater trochanter/lesser trochanter (G/L ratio) and trochanter valgus angle (TVA). RESULTS: Twelve patients (1 male and 11 female, average age 42.30 ± 10.23) had mean follow-up of 6 years. Among them, only two patients had intraoperative femoral fracture. The survivorship of femoral prosthesis was 100%. The Harris hip score (HHS) increased from preoperative 34.31 ± 14.43 to postoperative 84.12 ± 11.33. All patients' G/L ratio were larger than 1.50. CONCLUSIONS: The reverse sleeve of S-ROM was a reliable method for the patients with severe TVD, which brought satisfying clinical outcomes in mid-term follow-up.

Long-Term Clinical and Radiological Outcomes of Primary Total Hip Arthroplasty with Modular Femoral Stem in Middle-Aged Asian Patients.

BACKGROUND: There is insufficient information regarding the outcome of primary total hip arthroplasty (THA) with the modular femoral stem in middle-aged patients. This study aimed to assess long-term clinical and radiological outcomes of primary THA using the original or modified modular hip system (S-ROM) in middle-aged Asian patients. METHODS: A retrospective review identified 98 primary THAs that used a modular stem and were undertaken between 1997 and 2009 in patients younger than 58 years, for whom at least 5 years of follow-up data were available. Clinical data and radiograph assessments were reviewed to analyze differences between the original and modified modular stem groups. RESULTS: The mean patient follow-up duration was 148.3 months, and the follow-up ratio was 89.1%. The Kaplan-Meier analysis revealed that the survival rate of both stems was 98.9% at 10 years and 89.8% at 15 years. Although no statistically significant differences in the survival rate were observed between the stem designs, the original stem group had increased incidence of thigh pain compared with the modified stem group. In total, 12 and 54 hips showed change in stem alignment and osteolysis, respectively. CONCLUSION: The findings of this study show that the modular stems have a high survival rate, and results suggest positive outcomes among the Asian population over the long term. Although there were very few differences between the stem designs, the results suggest that the modified modular stem could prevent thigh pain and that selection of the implant based on the bone shape is important for THA.

Midterm Outcomes and Frequency of Osteolysis of Total Hip Arthroplasty Using Cementless Modular Stem for Asian Patients.

BACKGROUND: Modular stems are useful for total hip arthroplasty (THA) in anatomically difficult dysplasia. Here, we present mean 6.8-year outcomes of cementless primary THA using S-ROM-A (modified modular stem for Asian patients) femoral prosthesis in anatomically difficult cases. METHODS: Charts of 373 patients (461 hips) undergoing THA (mean age, 58 years) were reviewed for clinical evaluation of modified Merle d'Aubigné-Postel score and Kaplan-Meier survivorship with revision for any reason as the end point. For radiographic analysis, 331 patients (412 hips) followed up for ≥5 years were included. Bearing couples were metal-on-metal (n = 145), metal-on-polyethylene (n = 120), and ceramic-on-polyethylene (n = 147). Radiography and multiplanar computed tomography were performed. RESULTS: No postoperative dislocation or deep infection occurred. Mean modified Merle d'Aubigné-Postel score improved significantly (10.9 points preoperatively, 16.7 points at last follow-up; P < .001). Cumulative 5- and 10-year stem survival rates were 100% and 84%, respectively (95% confidence interval, 75%-93%). All stems were classified as bone ingrown fixation. Osteolysis occurred in metal-on-metal (42.8%) and metal-on-polyethylene (15.8%) groups. Mean time to osteolysis was ~3 years, with no significant difference between 3 groups (P = .264). In logistic regression, lower cup inclination angle was significantly associated with osteolysis (odds ratio, 0.914; 95% confidence interval, 0.84-0.99; P = .029). CONCLUSION: S-ROM-A femoral prosthesis achieved excellent midterm fixation, and the modular system was useful in primary THA with severe deformity. Bearing couples are potentially associated with adverse reactions to metal debris. S-ROM-A with ceramic-on-polyethylene bearing couples may be an option for anatomically difficult THA.

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.

Modular femoral neck failure after revision of a total hip arthroplasty: a finite element analysis.

The authors report on a case of modular femoral neck fracture which appeared 21 months after revision of acetabular component. The revision surgery was performed 8 years after the primary total hip arthroplasty due to aseptic loosening of the acetabular component. During acetabular revision, the primary implanted short (S, - 3.5 mm) femoral head was also exchanged with extra-long (XL, + 7.0 mm) femoral head fitting the modular femoral neck with a longer lever arm. Numerical analysis has shown that this has resulted in a 19.9% increase in tensile stress at the neck-stem coupling during normal walking cycle. This could result in microcrack initiation and propagation and finally lead to modular neck failure of the otherwise well-fixed stem. Surgeons should avoid excessive loading of the exchangeable neck (dual-modular) femoral stem designs as the stem-neck couplings are subject to corrosion and are not as reliable as monoblock stems.

Medium-term outcomes of the S-ROM modular femoral stem in revision hip replacement.

INTRODUCTION: The objective of this study was to analyse results achieved with the S-ROM modular stem in revision surgery. MATERIALS AND METHODS: A retrospective observational study was conducted from 2007 to 2015 including 51 patients who had a follow-up of ≥ 2 years and complete medical history. The mean age was 66.5 years old (34-87). The main reason for revision was aseptic loosening (38 cases, 74.5%), followed by infection (10, 19.6%), instability (2, 3.9%) and an adverse reaction associated with a metal-on-metal hip implant (1, 2%). Using the Paprosky classification, there were 22 cases of type I (43.1%), 27 of type II (52.9%) and 2 of type IIIA (4%). At the end of the follow-up, radiological parameters were assessed using Engh's criteria. Pre- and postoperative clinical status was assessed using the Harris Hip Score, a visual analogue scale and the Merle D'Aubigné score. RESULTS: The mean follow-up period was 5.7 years (2-10). The mean Harris Hip Score improved from 45.5 points (22-65) to 85.8 (55-100) (p < 0.001), and the final mean Merle D'Aubigné scores were 5.2, 4.6 and 5.6 for pain, ability to walk and mobility, respectively. Osseointegration was confirmed in all except one patient with fibrous non-union. No aseptic loosening has been recorded. Postoperative complications were deep infection in four cases (7.8%) and dislocation in three (5.9%). CONCLUSION: This study indicates good medium-term outcomes using a modular hip replacement system with porous-coated proximal sleeves in revision surgery in patients with Paprosky type I and II defects.

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.

Sensitivity and Specificity of Metal Ion Levels in Predicting "Pseudotumors" due to Taper Corrosion in Patients With Dual Taper Modular Total Hip Arthroplasty.

BACKGROUND: Currently, no serum metal ion threshold exists to identify adverse tissue reactions in total hip arthroplasty (THA) patients with taper corrosion. Our study aims to investigate the sensitivity and specificity of serum metal ions in detecting taper corrosion related pseudotumors in patients with dual taper modular THA. METHODS: A total of 148 patients with dual taper modular THA were investigated: (1) 90 patients with pseudotumors detected with metal artifact reduction sequence-magnetic resonance imaging (MARS-MRI) and (2) 58 patients without pseudotumors on MARS-MRI. Receiver operating characteristic curves were constructed to determine the sensitivity and specificity using different metal ion thresholds. The severity of intraoperative tissue damage was correlated with preoperative metal ion levels. RESULTS: Pseudotumor was associated with higher cobalt (5.0 µg/L vs 3.7 µg/L, P < .01) and Co/Cr ratio (6.0 vs 3.7, P < .01). The sensitivity and specificity for cobalt level of 2.8 µg/L and Co/Cr ratio of 3.8 in detecting taper corrosion-related pseudotumors on MARS-MRI was 88% and 32% and 70% and 50%, respectively. Higher intraoperative tissue damage grades demonstrated significantly higher Co/Cr ratios (8.6 vs 3.4, P = .03). CONCLUSION: Although metal ion levels alone should not be relied on as the sole parameter to determine revision surgery, cobalt level >2.8 µg/L and the Co/Cr ratio >3.8 are useful clinical diagnostic adjuncts in the systematic clinical evaluation for taper corrosion-related adverse tissue reactions in patients with dual modular taper THA.

Anthropometric Computed Tomography Reconstruction Identifies Risk Factors for Cortical Perforation in Revision Total Hip Arthroplasty.

BACKGROUND: The incidence of revision hip arthroplasty is increasing with nearly 100,000 annual procedures expected in the near future. Many surgeons use straight modular tapered stems in revisions; however, complications of periprosthetic fracture and cortical perforation occur, resulting in poor outcomes. Our objective was to identify patient demographics and femoral characteristics that predispose patients to cortical perforation when using the straight modular stems. METHODS: We used a computed tomography database and modeling software to identify patient demographics and morphologic femoral characteristics that predispose patients to cortical perforation during revision hip arthroplasty. Overall, 561 femurs from patients of various backgrounds were used, and statistical analysis was performed via the 2-sample t test. RESULTS: Decreased patient height (mean 163.0 vs 168.8 cm), radius of curvature (818 vs 939 mm), anterior-posterior (8.5 vs 13.8 mm) and medial-lateral (7.9 vs 11.3 mm) width of the isthmus, and distance of the isthmus from the greater trochanter (179 vs 186 mm) were all statistically significant risk factors for cortical perforation (P < .05). CONCLUSION: This study identifies several patient-specific risk factors for cortical perforation during revision hip arthroplasty using straight modular tapered stems and highlights the importance of preoperative planning especially in patients with shorter stature, proximal location of the femoral isthmus, narrow femoral canal, and smaller radius of curvature. Also, when using a mid-length modular tapered stem without an extended trochanteric osteotomy, consideration should be given to using a kinked stem to avoid anterior cortical perforation.

Corrosion and Adverse Local Tissue Reaction in One Type of Modular Neck Stem.

Modular neck stems allow for optimization of joint biomechanics by restoring anteversion, offset, and limb length. A potential disadvantage is the generation of metal ions from fretting and crevice corrosion. We identified 118 total hip arthroplasty implanted with one type of dual-modular femoral component. Thirty-six required revision due to adverse local tissue reaction. Multivariate analysis isolated females and low offset necks as risk factors for failure. Kaplan-Meir analysis revealed small stem sizes failed at a higher rate during early follow-up period. Although the cobalt/chrome levels were higher in the failed group, these tests had low diagnostic accuracy for ALTR, while MRI scan was more sensitive. We conclude that the complications related to the use of dual modular stems of this design outweigh the potential benefits.