Increased risk of revision in patients with non-traumatic femoral head necrosis: 11,589 cases compared to 416,217 cases with primary osteoarthritis in the NARA database, 1995–2011

Background and purpose

Previous studies of patients who have undergone total hip arthroplasty (THA) due to femoral head necrosis (FHN) have shown an increased risk of revision compared to cases with primary osteoarthritis (POA), but recent studies have suggested that this procedure is not associated with poor outcome. We compared the risk of revision after operation with THA due to FHN or POA in the Nordic Arthroplasty Register Association (NARA) database including Denmark, Finland, Norway, and Sweden.

Patients and methods

427,806 THAs performed between 1995 and 2011 were included. The relative risk of revision for any reason, for aseptic loosening, dislocation, deep infection, and periprosthetic fracture was studied before and after adjustment for covariates using Cox regression models.

Results

416,217 hips with POA (mean age 69 (SD 10), 59% females) and 11,589 with FHN (mean age 65 (SD 16), 58% females) were registered. The mean follow-up was 6.3 (SD 4.3) years. After 2 years of observation, 1.7% in the POA group and 3.0% in the FHN group had been revised. The corresponding proportions after 16 years of observation were 4.2% and 6.1%, respectively. The 16-year survival in the 2 groups was 86% (95% CI: 86–86) and 77% (CI: 74–80). After adjusting for covariates, the relative risk (RR) of revision for any reason was higher in patients with FHN for both periods studied (up to 2 years: RR = 1.44, 95% CI: 1.34–1.54; p < 0.001; and 2–16 years: RR = 1.25, 1.14–1.38; p < 0.001).

Interpretation

Patients with FHN had an overall increased risk of revision. This increased risk persisted over the entire period of observation and covered more or less all of the 4 most common reasons for revision.Several studies of patients with femoral head necrosis (FHN) who have undergone total hip arthroplasty (THA) have shown an increased risk of revision compared to cases with primary osteoarthritis, but the literature in this field is not unanimous (Chandler et al. 1981, Cornell et al. 1985, Mont and Hungerford 1995). We therefore estimated the risk of revision for patients with THA due to non-traumatic FHN and for patients with primary osteoarthritis (POA). To obtain a sufficiently large material, we used the Nordic Arthroplasty Register, which covers data from the Danish, Finnish, Norwegian, and Swedish national registries.     

Implant survival of the most common cemented total hip devices from the Nordic Arthroplasty Register Association database

Background and purpose — According to previous Nordic Arthroplasty Register Association (NARA) data, the 10-year implant survival of cemented total hip arthroplasties (THAs) is 94% in patients aged 65–74 and 96% in patients aged 75 or more. Here we report a brand-level comparison of cemented THA based on the NARA database, which has not been done previously.

Patients and methods — We determined the rate of implant survival of the 9 most common cemented THAs in the NARA database. We used Kaplan-Meier analysis with 95% CI to study implant survival at 10 and 15 years, and Cox multiple regression to assess survival and hazard ratios (HRs), with revision for any reason as endpoint and with adjustment for age, sex, diagnosis, and femoral head material.

Results — Spectron EF THA (89.9% (CI: 89.3–90.5)) and Elite THA (89.8% (CI: 89.0–90.6)) had the lowest 10-year survivorship. Lubinus (95.7% survival, CI: 95.5–95.9), MS 30 (96.6%, CI: 95.8–97.4), and C-stem THA (95.8%, CI: 94.8–96.8) had a 10-year survivorship of at least 95%. Lubinus (revision risk (RR)?=?0.77, CI: 0.73–0.81), Müller (RR =0.83, CI: 0.70–0.99), MS-30 (RR =0.73, CI: 0.63–0.86), C-stem (RR =0.70, CI: 0.55–0.90), and Exeter Duration THA (RR =0.84, CI: 0.77–0.90) had a lower risk of revision than Charnley THA, the reference implant.

Interpretation — The Spectron EF THA and the Elite THA had a lower implant survival than the Charnley, Exeter, and Lubinus THAs. Implant survival of the Müller, MS 30, CPT, and C-stem THAs was above the acceptable limit for 10-year survival.     

Hip resurfacing arthroplasty: short-term survivorship of 4,401 hips from the Finnish Arthroplasty Register

Background and purpose Population-based registry data from the Nordic Arthroplasty Register Association (NARA) and from the National Joint Register of England and Wales have revealed that the outcome after hip resurfacing arthroplasty (HRA) is inferior to that of conventional total hip arthroplasty (THA). We analyzed the short-term survival of 4,401 HRAs in the Finnish Arthroplasty Register.

Methods We compared the revision risk of the 4,401 HRAs from the Register to that of 48,409 THAs performed during the same time period. The median follow-up time was 3.5 (0–9) years for HRAs and 3.9 (0–9) years for THAs.

Results There was no statistically significant difference in revision risk between HRAs and THAs (RR = 0.93, 95% CI: 0.78–1.10). Female patients had about double the revision risk of male patients (RR = 2.0, CI: 1.4–2.7). Hospitals that had performed 100 or more HRA procedures had a lower revision risk than those with less than 100 HRAs (RR = 0.6, CI: 0.4–0.9). Articular Surface Replacement (ASR, DePuy) had inferior outcome with higher revision risk than the Birmingham Hip Resurfacing implant (BHR, Smith & Nephew), the reference implant (RR = 1.8, CI: 1.2–2.7).

Interpretation We found that HRA had comparable short-term survivorship to THA at a nationwide level. Implant design had an influence on revision rates. ASR had higher revision risk. Low hospital procedure volume worsened the outcome of HRA. Female patients had twice the revision risk of male patients.     

Dual-mobility cups for revision due to instability are associated with a low rate of re-revisions due to dislocation

Background and purpose Revision total hip arthroplasty (THA) due to recurrent dislocations is associated with a high risk of persistent instability. We hypothesized that the use of dual-mobility cups would reduce the risk of re-revision due to dislocation after revision THA.

Patients and methods 228 THA cup revisions (in 228 patients) performed due to recurrent dislocations and employing a specific dual-mobility cup (Avantage) were identified in the Swedish Hip Arthroplasty Register. Kaplan-Meier survival analysis was performed with re-revision due to dislocation as the primary endpoint and re-revision for any reason as the secondary endpoint. Cox regression models were fitted in order to calculate the influence of various covariates on the risk of re-revision.

Results 58 patients (25%) had been revised at least once prior to the index cup revision. The surgical approach at the index cup revision was lateral in 99 cases (44%) and posterior in 124 cases (56%). Median follow-up was 2 (0–6) years after the index cup revision, and by then 18 patients (8%) had been re-revised for any reason. Of these, 4 patients (2%) had been re-revised due to dislocation. Survival after 2 years with the endpoint revision of any component due to dislocation was 99% (95% CI: 97–100), and it was 93% (CI: 90–97) with the endpoint revision of any component for any reason. Risk factors for subsequent re-revision for any reason were age between 50–59 years at the time of the index cup revision (risk ratio (RR) = 5 when compared with age > 75, CI: 1–23) and previous revision surgery to the relevant joint (RR = 1.7 per previous revision, CI: 1–3).

Interpretation The risk of re-revision due to dislocation after insertion of dual-mobility cups during revision THA performed for recurrent dislocations appears to be low in the short term. Since most dislocations occur early after revision THA, we believe that this device adequately addresses the problem of recurrent instability. Younger age and prior hip revision surgery are risk factors for further revision surgery. However, problems such as potentially increased liner wear and subsequent aseptic loosening may be associated with the use of such devices in the long term.     

Total hip replacement after femoral neck fractures in elderly patients : Results of 8,577 fractures reported to the Norwegian Arthroplasty Register

Background?A total hip arthroplasty (THA) is often used as treatment for failed osteosynthesis of femoral neck fractures and is now also used for acute femoral neck fractures. To investigate the results of THA after femoral neck fractures, we used data from the Norwegian Arthroplasty Register (NAR).

Patients and methods?The results of primary total hip replacements in patients with acute femoral neck fractures (n = 487) and sequelae after femoral neck fractures (n = 8,090) were compared to those of total hip replacements in patients with osteoarthrosis (OA) (n = 55,109). The hips were followed for 0–18 years. The Cox multiple regression model was used to construct adjusted survival curves and to adjust for differences in sex, age, and type of cement among the diagnostic groups. Separate analyses were done on the subgroups of patients who were operated with Charnley prostheses.

Results?The survival rate of the implants after 5 years was 95% for the patients with acute fractures, 96% for the patients with sequelae after fracture, and 97% for the OA patients. With adjustment for age, sex, and type of cement, the patients with acute fractures had an increased risk of revision compared to the OA patients (RR 1.6, 95% CI: 1.0–2.6; p = 0.05) and the sequelae patients had an increased risk of revision (RR 1.3, 95% CI: 1.2–1.5; p < 0.001). Sequelae hips had higher risk of revision due to dislocation (RR 2.0, 95% CI: 1.6–2.4; p < 0.001) and periprosthetic fracture (RR 2.2, 95% CI: 1.5–3.3; p < 0.001), and lower risk of revision due to loosening of the acetabular component (RR 0.72, 95% CI; 0.57–0.93; p = 0.01) compared to the OA patients. The increased risk of revision was most apparent for the first 6 months after primary operation.

Interpretation?THA in fracture patients showed good results, but there was an increased risk of early dislocations and periprosthetic fractures compared to OA patients.     

Total hip arthroplasty for rheumatoid arthritis in younger patients: 2,557 replacements in the Finnish Arthroplasty Register followed for 0–24 years

Background?The results of total hip arthroplasty (THA) in young patients with rheumatoid arthritis (RA) have been reported in only a few studies. On a nationwide level, the outcome of THA in these patients is unknown. We evaluated the population-based survival of THA in patients under 55 years of age with RA and factors affecting the survival.

Patients?Between 1980 and 2003, 2,557 primary THAs performed for RA in patients less than 55 years of age were reported to the Finnish Arthroplasty Register.

Results?Proximally circumferentially porous-coated uncemented stems had a 15-year survival rate of 89% (95% CI 83–94) with aseptic loosening as endpoint. The risk of stem revision due to aseptic loosening was higher with cemented stems than with proximally porouscoated uncemented stems implanted during the same period (RR 2.4; p < 0.001). In contrast, Cox regression analysis showed that the risk of cup revision was significantly higher for all uncemented cup concepts than for all-polyethylene cemented cups with any cup revision as endpoint. There were no significant differences in survival between the THR concepts.

Interpretations?Uncemented proximally circumferentially porous-coated stems and cemented all-poly-ethylene cups are currently the implants of choice for young patients with RA.     

Comparison of the risk of revision in cementless total hip arthroplasty with ceramic-on-ceramic and metal-on-polyethylene bearings

Background and purpose — Ceramic-on-ceramic (CoC) bearings were introduced in total hip arthroplasty (THA) to reduce problems related to polyethylene wear. We compared the 9-year revision risk for cementless CoC THA and for cementless metal-on-polyethylene (MoP) THA.

Patients and methods — In this prospective, population-based study from the Danish Hip Arthroplasty Registry, we identified all the primary cementless THAs that had been performed from 2002 through 2009 (n = 25,656). Of these, 1,773 THAs with CoC bearings and 9,323 THAs with MoP bearings were included in the study. To estimate the relative risk (RR) of revision, we used regression with the pseudo-value approach and treated death as a competing risk.

Results — 444 revisions were identified: 4.0% for CoC THA (71 of 1,773) and 4.0% for MoP THA (373 of 9,323). No statistically significant difference in the risk of revision for any reason was found for CoC and MoP bearings after 9 years of follow-up (adjusted RR = 1.3, 95% CI: 0.72–2.4). Revision rates due to component failure were 0.5% (n = 8) for CoC bearings and 0.1% (n = 6) for MoP bearings (p < 0.001). 6 patients with CoC bearings (0.34%) underwent revision due to ceramic fracture.

Interpretation — When compared to the “standard” MoP bearings, CoC THA had a 33% higher (though not statistically significantly higher) risk of revision for any reason at 9 years.     

What Factors Predict Conversion to THA After Arthroscopy?

Background

Failure of hip preservation to alleviate symptoms potentially subjects the patient to reoperation or conversion surgery to THA, adding recovery time, risk, and cost. A risk calculator using an algorithm that can predict the likelihood that a patient who undergoes arthroscopic hip surgery will undergo THA within 2 years would be helpful, but to our knowledge, no such tool exists.

Questions

(1) Are there preoperative and intraoperative variables at the time of hip arthroscopy associated with subsequent conversion to THA? (2) Can these variables be used to develop a predictive tool for conversion to THA?

Materials and Methods

All patients undergoing arthroscopy from January 2009 through December 2011 were registered in our longitudinal database. Inclusion criteria for the study group were patients undergoing hip arthroscopy for a labral tear, who eventually had conversion surgery to THA. Patients were compared with a control group of patients who underwent hip arthroscopy for a labral tear but who did not undergo conversion surgery to THA during the same study period. Of the 893 who underwent surgery during that time, 792 (88.7%) were available for followup at a minimum of 2 years (mean, 31.1 ± 8.1 years) and so were considered in this analysis. Multivariate regression analyses of 41 preoperative and intraoperative variables were performed. Using the results of the multivariate regression, we developed a simplified calculator that may be helpful in counseling a patient regarding the risk of conversion to THA after hip arthroscopy.

Results

Variables simultaneously associated with conversion to THA in this model were older age (rate ratio, 1.06; 95% CI, 1.03–1.08; p < 0.0001), lower preoperative modified Harris hip score (rate ratio [RR], 0.98; 95% CI, 0.96–0.99; p = 0.0003), decreased femoral anteversion (RR, 0.97; 95% CI, 0.94–0.99; p = 0.0111), revision surgery (RR, 2.4; 95% CI, 1.15–5.01; p = 0.0193), femoral Outerbridge Grades II to IV (Grade II: RR, 2.23 [95% CI, 1.11–4.46], p = 0.023; Grade III: RR, 2.17, [95% CI, 1.11–4.23], p = 0.024; Grade IV: RR, 2.96 [95% CI, 1.34–6.52], p = 0.007), performance of acetabuloplasty (RR, 1.83; 95% CI, 1.03–3.24; p = 0.038), and lack of performance of femoral osteoplasty (RR, 0.62; 95% CI, 0.36–1.06; p = 0.081). Using the results of the multivariate regression, we developed a simplified calculator that may be helpful in counseling a patient regarding the risk of conversion surgery to THA after hip arthroscopy.

Conclusion

Multiple risk factors have been identified as possible risk factors for conversion to THA after hip arthroscopy. A weighted calculator based on our data is presented here and may be useful for predicting failure after hip arthroscopy for labral treatment. Determining the best candidates for hip preservation remains challenging; careful attention to long-term followup and identifying characteristics associated with successful outcomes should be the focus of further study.

Level of Evidence

Level III, therapeutic study.

     

Increased risk of intraoperative and early postoperative periprosthetic femoral fracture with uncemented stems

Background and purpose — The use of uncemented fixation in total hip arthroplasty (THA) is increasing. Registry studies have indicated an increased risk of revision of uncemented implants due to early periprosthetic femoral fracture. In this paper, we describe the incidence and predisposing factors for intraoperative and early postoperative (≤ 90 days) periprosthetic femoral fractures after cemented and uncemented THA.

Patients and methods — This was a prospective observational study in 8 Danish high-volume centers from February 2010 to November 2013. We used the 90-day follow-up from the Danish National Patient Registry and patient records. We obtained intraoperative information from the Danish Hip Arthroplasty Registry and from surgical notes.

Results — Of 7,169 primary consecutive THAs, 5,482 (77%) were performed using uncemented femoral components. The total incidence of periprosthetic femoral fractures ≤ 90 days postoperatively was 2.1% (n = 150). 70 fractures were detected intraoperatively (46 required osteosynthesis). 51 postoperatively detected fractures occurred without trauma (42 of which were reoperated) and 29 were postoperative fall-related fractures (27 of which were reoperated). 134 fractures (2.4%) were found in uncemented femoral components and 16 (0.9%) were found in cemented femoral components (p < 0.001). Uncemented femoral stem (relative risk (RR)?=?4.1, 95% CI: 2.3–7.2), medically treated osteoporosis (RR =2.8, CI: 1.6–4.8), female sex (RR =1.6, CI: 1.1–2.2), and age (RR =1.4 per 10 years, CI: 1.2–1.6) were associated with increased risk of periprosthetic femoral fracture when analyzed using multivariable regression analysis.

Interpretation — Uncemented femoral components were associated with an increased risk of early periprosthetic femoral fractures, especially in elderly, female, and osteoporotic patients.     

Use of diuretics and risk of implant failure after primary total hip arthroplasty: A nationwide population-based study

IntroductionThiazid and loop diuretics have been associated with changes in bone mineral density and fracture risk. However, data on survival of prosthesis implants are lacking. We evaluated the association between diuretic use and the risk of revision after primary total hip arthroplasty (THA).Materials and methodsWe conducted a nationwide population-based case-control study using medical databases in Denmark. In the Danish Hip Arthroplasty Registry, we identified 2491 cases that were revised after primary THA in the period 1995–2005 and who could be matched on age, gender and year of primary operation with 4943 non-revised THA controls. By means of conditional logistic regression, we estimated the relative risk (RR) of revision due to all causes and due to specific causes according to postoperative use of thiazid and loop diuretic, respectively.ResultsThe 10-year cumulated implant revision rate in the underlying cohort of 57,575 THA procedures from the Danish Hip Arthroplasty Registry was 8.9% (95% CI: 8.4–9.4). Postoperative thiazid diuretic use was not associated with neither the overall risk of revision nor revision due to specific causes compared to non-use. Postoperative loop diuretic use was associated with an adjusted RR of revision of 1.14 (95% CI; 0.98–1.32) compared with non-use. The adjusted RR of revision due to deep infection and periprosthetic fracture in loop diuretic users was 1.71 (1.15–2.55) and 6.39 (1.84–22.21), respectively. Loop diuretic use was not associated with risk of revision due to aseptic loosening, dislocation or miscellaneous causes.DiscussionLoop diuretics but not thiazides may be associated with an increased risk of revision following primary THA. Further studies are warranted in order to confirm this finding and clarify the nature of the association.     

Postoperative opioid use as an early indication of total hip arthroplasty failure

Background and purpose — A criticism of total hip arthroplasty (THA) survivorship analysis is that revisions are a late and rare outcome. We investigated whether prolonged opioid use is a possible indicator of early THA failure.

Patients and methods — We conducted a cohort study of THAs registered in a total joint replacement registry from January 2008 to December 2011. 12,859 patients were evaluated. The median age was 67 years and 58% were women. Opioid use in the year after surgery was the exposure of interest, and the cumulative daily amounts of oral morphine equivalents (OMEs) were calculated. Post-THA OMEs per 90?day periods were categorized into quartiles. The endpoints were 1- and 5-year revisions.

Results — After the first 90 days, 27% continued to use opioids. The revision rate was 0.9% within a year and 1.7% within 5 years. Use of medium-low (100–219?mg), medium-high (220–533?mg), and high (≥ 534?mg) amounts of OMEs in days 91–180 after surgery was associated with a 6 times (95% confidence interval (CI): 3–15), 5 times (CI: 2–13), and 11 times (CI: 2.9–44) higher adjusted risk of 1 year revision, respectively. The use of medium-low and medium-high amounts of OMEs in days 181–270 after surgery was associated with a 17 times (CI: 6–44) and 14 times (95% CI: 4–46) higher adjusted risk of 1-year revision. There was a similar higher risk of 5-year revision.

Interpretation — Persistent postoperative use of opioids was associated with revision THA surgery in this cohort, and it may be an early indicator of potential surgical failures.     

The type of surgical approach influences the risk of revision in total hip arthroplasty

Background and purpose The most common surgical approaches in total hip arthroplasty in Sweden are the posterior and the anterolateral transgluteal approach. Currently, however, there is insufficient evidence to prefer one over the other regarding risk of subsequent surgery.

Patients and methods We searched the Swedish Hip Arthroplasty Register between the years 1992 and 2009 to compare the posterior and anterolateral transgluteal approach regarding risk of revision in the 3 most common all-cemented hip prosthesis designs in Sweden. 90,662 total hip replacements met the inclusion criteria. We used Cox regression analysis for estimation of prosthesis survival and relative risk of revision due to dislocation, infection, or aseptic loosening.

Results Our results show that for the Lubinus SPII prosthesis and the Spectron EF Primary prosthesis, the anterolateral transgluteal approach gave an increased risk of revision due to aseptic loosening (relative risk (RR) = 1.3, 95% CI: 1.0–1.6 and RR = 1.6, CI: 1.0–2.5) but a reduced risk of revision due to dislocation (RR = 0.7, CI: 0.5–0.8 and RR = 0.3, CI: 0.1–0.4). For the Exeter Polished prosthesis, the surgical approach did not affect the outcome for dislocation or aseptic loosening. The surgical approach had no influence on the risk of revision due to infection in any of these designs.

Interpretation This observational study shows that the surgical approach affected the risk of revision due to aseptic loosening and dislocation for 2 of the most commonly used cemented implants in Sweden. Further studies are needed to determine whether these results are generalizable to other implants and to uncemented fixation.     

Poor 10-year survivorship of hip resurfacing arthroplasty

Background and purpose — In a previous registry report, short-term implant survival of hip resurfacing arthroplasty (HRA) in Finland was found to be comparable to that of total hip arthroplasty (THA). Since then, it has become evident that adverse reactions to metal debris (ARMDs) may also be associated with HRA, not only with large-diameter head metal-on-metal THA. The aim of the study was to assess medium- to long-term survivorship of HRA based on the Finnish Arthroplasty Register (FAR).

Patients and methods — 5,068 HRAs performed during the period 2001–2013 in Finland were included. Kaplan-Meier survival analysis was used to calculate survival probabilities and their 95% confidence intervals (CIs). Cox multiple regression, with adjustment for age, sex, diagnosis, femoral head size, and hospital volume was used to analyze implant survival of HRA devices with revision for any reason as endpoint. The reference group consisted of 6,485 uncemented Vision/Bimetric and ABG II THAs performed in Finland over the same time period.

Results — The 8-year survival, with any revision as an endpoint, was 93% (CI: 92–94) for Birmingham Hip Resurfacing (BHR), 86% (CI: 78–94) for Corin, 91% (CI: 89–94) for ReCap, 92% (CI: 89–96) for Durom, and was 72% (CI: 69–76) for the Articular Surface Replacement (ASR). The 10-year survival, with any revision as an endpoint, for reference THAs was 92% (CI: 91–92) and for all HRAs it was 86% (CI: 84–87%). Female HRA patients had about twice the revision risk of male patients. ASR had an inferior outcome: the revision risk was 4-fold higher than for BHR, the reference implant.

Interpretation — The 10-year implant survival of HRAs is 86% in Finland. According to new recommendations from NICE (The National Institute for Health and Care Excellence), an HRA/THA should have a revision rate of 5% or less at 10 years. None of the HRAs studied achieved this goal.     

Conversion from failed hemiarthroplasty to total hip arthroplasty: A Norwegian Arthroplasty Register analysis of 595 hips with previous femoral neck fractures

Background and purpose?Conversion total hip replacement (THR) is a common procedure after failed hemiarthroplasty, but there have been few reports describing the long-term outcome of this procedure.

Patients and methods?Between 1987 and 2004, 595 THRs were reported to the Norwegian Arthroplasty Register as conversion THR for failed hemiarthroplasty after a femoral neck fracture in patients aged 60 years and older. 122 operations left the femoral stem intact, whereas 473 were converted with exchange of the femoral stem.

Results?We found a lower risk of failure (revision surgery for any reason) for the conversion procedures with stem exchange (RR = 0.4; 95% CI: 0.25–0.81) than for the conversion procedures that retained the femoral stem. For the 473 conversion arthroplasties with exchange of the stem, we found no difference in risk of failure compared to all revision stems in the register, either for the complete prosthesis (RR = 0.8; CI: 0.50– 1.20) or for the stem (RR = 0.9; CI: 0.53–1.59). However, for the 122 conversion procedures in which the femoral stem was retained, we found a significantly increased risk of failure for both the complete prosthesis (RR = 4.6; CI: 2.8–7.6) and for the acetabular cup (RR = 4.8; CI: 2.3–10) compared to primary hip arthroplasties.

Interpretation?Our findings indicate that the seemingly easy operation of implanting an acetabular cup to convert a hemiarthroplasty to a total hip arthroplasty is an uncertain procedure and that the threshold for replacing the stem should be low.     

Low revision rate after total hip arthroplasty in patients with pediatric hip diseases

Background The results of primary total hip arthroplasties (THAs) after pediatric hip diseases such as developmental dysplasia of the hip (DDH), slipped capital femoral epiphysis (SCFE), or Perthes’ disease have been reported to be inferior to the results after primary osteoarthritis of the hip (OA).

Materials and methods We compared the survival of primary THAs performed during the period 1995–2009 due to previous DDH, SCFE, Perthes’ disease, or primary OA, using merged individual-based data from the Danish, Norwegian, and Swedish arthroplasty registers, called the Nordic Arthroplasty Register Association (NARA). Cox multiple regression, with adjustment for age, sex, and type of fixation of the prosthesis was used to calculate the survival of the prostheses and the relative revision risks.

Results 370,630 primary THAs were reported to these national registers for 1995–2009. Of these, 14,403 THAs (3.9%) were operated due to pediatric hip diseases (3.1% for Denmark, 8.8% for Norway, and 1.9% for Sweden) and 288,435 THAs (77.8%) were operated due to OA. Unadjusted 10-year Kaplan-Meier survival of THAs after pediatric hip diseases (94.7% survival) was inferior to that after OA (96.6% survival). Consequently, an increased risk of revision for hips with a previous pediatric hip disease was seen (risk ratio (RR) 1.4, 95% CI: 1.3–1.5). However, after adjustment for differences in sex and age of the patients, and in fixation of the prostheses, no difference in survival was found (93.6% after pediatric hip diseases and 93.8% after OA) (RR 1.0, CI: 1.0–1.1). Nevertheless, during the first 6 postoperative months more revisions were reported for THAs secondary to pediatric hip diseases (RR 1.2, CI: 1.0–1.5), mainly due to there being more revisions for dislocations (RR 1.8, CI: 1.4–2.3). Comparison between the different diagnosis groups showed that the overall risk of revision after DDH was higher than after OA (RR 1.1, CI: 1.0–1.2), whereas the combined group Perthes’ disease/SCFE did not have a significantly different risk of revision to that of OA (RR 0.9, CI: 0.7–1.0), but had a lower risk than after DDH (RR 0.8, CI: 0.7–1.0).

Interpretation After adjustment for differences in age, sex, and type of fixation of the prosthesis, no difference in risk of revision was found for primary THAs performed due to pediatric hip diseases and those performed due to primary OA.     

Uncemented cups with and without screw holes in primary THA: a Swedish Hip Arthroplasty Register study with 22,725 hips

Background and purpose — Uncemented cups in total hip arthroplasty (THA) are often augmented with additional screws to enhance their primary stability. We investigated whether there is a difference in the risk for revision between cups with screw holes and cups without screw holes.

Patients and methods — We analyzed the risk for cup revision of uncemented cups registered in the Swedish Hip Arthroplasty Register (SHAR) between 2000 and 2017 with respe ct to the presence of screw holes. Only patients with primary osteoarthritis (OA) were included. 22,725 cups, including 12,354 without screw holes and 10,371 with screw holes, were evaluated. Revision rates at 2 and 10 years after the primary operation were analyzed.

Results — At a median follow-up time of 3.4 years (0–18), 459?cup revisions were reported. The main reasons for cup revision during the whole observation time were infection, 52% of all cup revisions, and dislocation, 26% of all cup revisions. The survival rate with cup revision due to aseptic loosening as endpoint was 99.9% (95% CI 99.8–99.9) at 2 years for both cups with and cups without screw holes, and the survival rates at 10 years were 99.5% (CI 99.3–99.7) and 99.1% (CI 98.6–99.5), respectively. Cups without screw holes showed a decreased risk of revision due to any reason at both 2 years (adjusted hazard ratio [HR] 0.6, CI 0.5–0.8) and 10 years (HR 0.7, CI 0.5–0.9).

Interpretation — We found a very low revision rate for aseptic loosening with modern, uncemented cup designs. Cups with screw holes had an increased risk of revision due to any reason in patients with primary OA     

What Risks are Associated with Primary THA in Recipients of Hematopoietic Stem Cell Transplantation?

Introduction

As patients who receive hematopoietic stem cell transplantation are at increased risk of avascular necrosis (AVN) and subsequent degenerative arthritis, THA may be considered in some of these patients, particularly as overall patient survival improves for patients undergoing stem-cell transplants. Patients receiving hematopoietic stem cell transplantation theoretically are at increased risk of experiencing complications, infection, and poorer implant survivorship owing to the high prevalence of comorbid conditions, immunosuppressive therapy regimens including corticosteroids, and often low circulating hematopoietic cell lines; however, there is a paucity of studies elucidating these risks.

Questions/Purposes

We asked: (1) What is the overall mortality of patients with hematopoietic stem cell transplantation who have undergone THA? (2) What is the complication rate for these patients? (3) What are the revision and reoperation rates and implant survivorship for these patients?

Patients and Methods

Between 1999 and 2013, we performed 42 THAs in 36 patients who underwent stem-cell transplants. Other than those who died, all were available for followup at a minimum of 2 years; of the patients whose procedures were done more than 10 years ago and who are not known to have died, two (5%) had not been seen in the last 5 years and so are considered lost to followup. All patients underwent thorough evaluation by the transplant team before arthroplasty; general contraindications included active medical comorbidities or evidence of unstable end-organ damage, active rejection, and critically low circulating hematopoietic cell lines. Underlying primary diseases leading to hematopoietic stem cell transplantation included lymphoma (14/42; 33%), plasma cell disorders (10/42; 24%), leukemia (9/42; 21%), and amyloidosis (3/42; 7%). Complications, reoperations, revisions, and implant and patient survivorship, were recorded from chart review and data from the institutional total joint registry. Mean followup was 5 years (range, 2–15 years).

Results

Patient survivorship free of mortality was 91% (95% CI, 81%–100%) and 82% (95% CI, 68%–96%) at 2 and 5 years, respectively. Complications occurred in four of 42 THAs (10%); these complications included an intraoperative fracture and a venous thromboembolism. Revisions occurred in two of 42 (5%) THAs; there were no reoperations. Implant survivorship free of component revision for any reason or implant removal accounting for death as a competing risk was 93% (95% CI, 83%–100%) at 5 years.

Conclusion

With appropriate medical evaluation and comanagement by transplant specialists, carefully selected patients with hematopoietic stem cell transplants may undergo elective primary THA, although complications do occur in this relatively fragile patient population. Although implant survivorship was modest at 93% at 5 years, there was not a high risk of revision for infection. Improved outcomes for these patients may be expected as their medical management advances and additional comparative studies may clarify other important patient factors.

Level of Evidence

Level IV, therapeutic study.

     

Results of 189 wrist replacements

Background and purpose There is very little literature on the long-term outcome of wrist replacements. The Norwegian Arthroplasty Register has registered wrist replacements since 1994. We report on the total wrist replacements and their revision rates over a 16-year period.

Material and methods 189 patients with 189 primary wrist replacements (90 Biax prostheses (80 of which were cementless), 23 cementless Elos prostheses, and 76 cementless Gibbon prostheses), operated during the period 1994–2009 were identified in the Norwegian Arthroplasty Register. Prosthesis survival was analyzed using Cox regression analyses. The 3 implant designs were compared and time trends were analyzed.

Results The 5-year survival was 78% (95% CI: 70–85) and the 10-year survival was 71% (CI: 59–80). Prosthesis survival was 85% (CI: 78–93) at 5 years for the Biax prosthesis, 77% (CI: 30–90) at 4 years for the Gibbon prosthesis, and 57% (CI: 33–81) at 5 years for the Elos prosthesis. There was no statistically significant influence of age, diagnosis, or year of operation on the risk of revision, but females had a higher revision rate than males (RR = 3, CI: 1–7). The number of wrist replacements performed due to osteoarthritis increased with time, but no such change was apparent for inflammatory arthritis.

Interpretation The survival of the total wrist arthroplasties studied was similar to that in other studies of wrist arthroplasties, but it was still not as good as that for most total knee and hip arthroplasties. However, a failed wrist arthroplasty still leaves the option of a well-functioning arthrodesis.     

Hemiarthroplasty and total hip arthroplasty in 30,830 patients with hip fractures: data from the Dutch Arthroplasty Register on revision and risk factors for revision

Background and purpose — In the Netherlands about 40% of hip fractures are treated with a hemiarthroplasty (HA) or a total hip arthroplasty (THA). Although these procedures are claimed to have fewer complications than osteosynthesis (i.e., reoperation), complications still occur. Analyses of data from national registries with adequate completeness of revision surgery are important to establish guidelines to diminish the risk for revision. We identified risk factors for revision.

Patients and methods — All patients older than 50 years of age with a hip fracture treated with arthroplasty by orthopedic surgeons and registered in the (national) Dutch arthroplasty register (LROI) were included in the study. In this register, patient characteristics and surgical details were prospectively collected. Revision surgery and reasons for revision were evaluated. A proportional hazard ratio model for revision was created using competing risk analysis (with death as competing risk).

Results — 1-year revision rate of HA was (cumulative incidence function [CIF] 1.6% (95% CI 1.4–1.8) and THA 2.4% (CI 2.0–2.7). Dislocation was the most common reason for revision in both groups (HA 29%, THA 41%). Male sex, age under 80 years, posterolateral approach, and uncemented stem fixation were risk factors for revision in both THA and HA. THA patients with ASA classification III/IV were revised more often, whereas revision in the HA cohort was performed more often in ASA I/II patients.

Interpretation — After arthroplasty of hip fractures, both a posterolateral approach and an uncemented hip stem have higher risks for revision surgery compared with an anterolateral approach and an cemented stem.     

A Case of Pseudarthrosis of the Neck of the Femur,Treated by the Method of Extra-Articular Ostesynthesis

Background and purpose Monoblock acetabular cups represent a subtype of uncemented cups with the polyethylene liner molded into a metal shell, thus eliminating—or at least minimizing—potential backside wear. We hypothesized that the use of monoâ€?block cups could reduce the incidence of osteolysis and aseptic loosening, and thus improve survival compared to modular designs.

Patients and methods We identified all 210 primary total hip arthroplasty (THA) procedures in the Swedish Hip Arthroplasty Register that used uncemented monoblock cups during the period 1999–2010. Kaplan-Meier and Cox regression analyses with adjustment for age, sex, and other variables were used to calculate survival rates and adjusted hazard ratios (HRs) of the revision risk for any reason. 1,130 modular cups, inserted during the same time period, were used as a control group.

Results There was a nearly equal sex distribution in both groups. Median age at the index operation was 47 years in the monoblock group and 56 years in the control group (p < 0.001). The cumulative 5-year survival with any revision as the endpoint was 95% (95% CI: 91–98) for monoblock cups and 97% (CI: 96–98) for modular cups (p = 0.6). The adjusted HR for revision of monoblock cups compared to modular cups was 2 (CI: 0.8–6; p = 0.1). The use of 28-mm prosthesis heads rather than 22-mm heads reduced the risk of cup revision (HR = 0.2, CI: 0.1–0.5; p = 0.001).

Interpretation Both cups showed good medium-term survival rates. There was no statistically significant difference in revision risk between the cup designs. Further review of the current patient population is warranted to determine the long-term durability and risk of revision of monoblock cup designs.