Eva Dybvik

Future clinical and economic impact of revision total hip and knee arthroplasty

A recent analysis of historical procedure data indicated that the prevalence of primary and revision total hip and total knee arthroplasty increased steadily between 1990 and 20021. A massive demand for primary and revision surgeries is also expected in the next two decades2. Similarly, the overall incidence of deep infection also has increased substantially between 1990 and 2003 for both total hip arthroplasty and total knee arthroplasty3. In 2003, approximately 1.2% of the total hip arthroplasties performed in the United States were associated with deep infection, which was similar to the rate seen for total knee arthroplasties3. Deep infection is a catastrophic complication of both total hip and total knee arthroplasty, and it also represents a tremendous economic burden4,5. The implications for a growing incidence of infections, coupled with accelerating demand for arthroplasty, remain unexplored. Long-term survival of total hip arthroplasty and total knee arthroplasty implants has been investigated by Scandinavian arthroplasty registries6-8. However, in the United States, national hip and knee registries have not been established9,10. Medicare claims data have been used effectively in longitudinal analysis of mortality and morbidity following joint replacement11, but the feasibility of using this data as a registry substitute is unclear. Along with the projected increase in the utilization of total hip arthroplasty and total knee arthroplasty2, retrospective studies have shown increasing disparity between Medicare reimbursement and hospital charges, with higher charges for revision than for primary procedures12-14. The economic consequences of the projected demand for total hip arthroplasty and total knee arthroplasty are still unknown. The goals of our study were to (1) quantify the future number of infections at the site of arthroplasties done …

Metal-backed acetabular components with conventional polyethylene: A REVIEW OF 9113 PRIMARY COMPONENTS WITH A FOLLOW-UP OF 20 YEARS

The Norwegian Arthroplasty Register has shown that several designs of uncemented femoral stems give good or excellent survivorship. The overall findings for uncemented total hip replacement however, have been disappointing because of poor results with the use of metal-backed acetabular components. In this study, we exclusively investigated the medium-to long-term performance of primary uncemented metal-backed acetabular components. A total of 9113 primary uncemented acetabular components were implanted in 7937 patients between 1987 and 2007. These were included in a prospective, population-based observational study. All the implants were modular and metal-backed with ultra-high-molecular-weight polyethylene liners. The femoral heads were made of stainless steel, cobalt-chrome (CoCr) alloy or alumina ceramic. In all, seven different designs of acetabular component were evaluated by the Kaplan-Meier survivorship method and Cox regression analysis. Most acetabular components performed well up to seven years. When the endpoint was revision of the acetabular component because of aseptic loosening, the survival ranged between 87% and 100% at ten years. However, when the endpoint was revision for any reason, the survival estimates were 81% to 92% for the same implants at ten years. Aseptic loosening, wear, osteolysis and dislocation were the main reasons for the relatively poor overall performance of the acetabular components. Prostheses with alumina heads performed slightly better than those with stainless steel or CoCr alloy in subgroups. Whereas most acetabular components performed well at seven years, the survivorship declined with longer follow-up. Fixation was generally good. None of the metal-backed uncemented acetabular components with ultra-high-molecular-weight polyethylene liners in our study had satisfactory long-term results because of high rates of wear, osteolysis, aseptic loosening and dislocation.

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.

Complications after intramedullary nailing of femoral fractures in a low-income country: A prospective study of follow-up, HIV infection, and microbial infection rates after IM nailing of 141 femoral fractures at a central hospital in Malawi

Background Some surgeons believe that internal fixation of fractures carries too high a risk of infection in low-income countries (LICs) to merit its use there. However, there have been too few studies from LICs with sufficient follow-up to support this belief. We first wanted to determine whether complete follow-up could be achieved in an LIC, and secondly, we wanted to find the true microbial infection rate at our hospital and to examine the influence of HIV infection and lack of follow-up on outcomes. Patients and methods 137 patients with 141 femoral fractures that were treated with intramedullary (IM) nailing were included. We compared outcomes in patients who returned for scheduled follow-up and patients who did not return but who could be contacted by phone or visited in their home village. Results 79 patients returned for follow-up as scheduled; 29 of the remaining patients were reached by phone or outreach visits, giving a total follow-up rate of 79%. 7 patients (5%) had a deep postoperative infection. All of them returned for scheduled follow-up. There were no infections in patients who did not return for follow-up, as compared to 8 of 83 nails in the group that did return as scheduled (p = 0.1). 2 deaths occurred in HIV-positive patients (2/23), while no HIV-negative patients (0/105) died less than 30 days after surgery (p = 0.03). Interpretation We found an acceptable infection rate. The risk of infection should not be used as an argument against IM nailing of femoral fractures in LICs. Many patients in Malawi did not return for follow-up because they had no complaints concerning the fracture. There was an increased postoperative mortality rate in HIV-positive patients.

Is reverse hybrid hip replacement the solution

Background and purpose Reverse hybrid hip replacement uses a cemented all-polyethylene cup and an uncemented stem. Despite increasing use of this method in Scandinavia, there has been very little documentation of results. We have therefore analyzed the results from the Norwegian Arthroplasty Register (NAR), with up to 10 years of follow-up. Patients and methods The NAR has been collecting data on total hip replacement (THR) since 1987. Reverse hybrid hip replacements were used mainly from 2000. We extracted data on reverse hybrid THR from this year onward until December 31, 2009, and compared the results with those from cemented implants over the same period. Specific cup/stem combinations involving 100 cases or more were selected. In addition, only combinations that were taken into use in 2005 or earlier were included. 3,963 operations in 3,630 patients were included. We used the Kaplan-Meier method and Cox regression analysis for estimation of prosthesis survival and relative risk of revision. The main endpoint was revision for any cause, but we also performed specific analyses on different reasons for revision. Results We found equal survival to that from cemented THR at 5 years (cemented: 97.0% (95% CI: 96.8–97.2); reverse hybrid: 96.7% (96.0–97.4)) and at 7 years (cemented: 96.0% (95.7–96.2); reverse hybrid: 95.6% (94.4–96.7)). Adjusted relative risk of revision of the reverse hybrids was 1.1 (0.9–1.4). In patients under 60 years of age, we found similar survival of the 2 groups at 5 and 7 years, with an adjusted relative risk of revision of reverse hybrids of 0.9 (0.6–1.3) compared to cemented implants. Interpretation With a follow-up of up to 10 years, reverse hybrid THRs performed well, and similarly to all-cemented THRs from the same time period. The reverse hybrid method might therefore be an alternative to all-cemented THR. Longer follow-up time is needed to evaluate whether reverse hybrid hip replacement has any advantages over all-cemented THR.

Improved outcome after hip fracture surgery in Norway

Background and purpose — The operative treatment of hip fractures in Norway has changed considerably during the last decade. We used data in the Norwegian Hip Fracture Register to investigate possible effects of these changes on reoperations and 1-year mortality. Patients and methods — 72,741 femoral neck (FFN) fractures and trochanteric fractures in patients 60 years or older were analyzed. The fractures were divided into 5 time periods (2005–2006, 2007–2008, 2009–2010, 2011–2012, 2013–2014). Cox regression models were used to calculate unadjusted and adjusted (age group, sex, and ASA class) relative risks (RRs) of reoperation and of 1-year mortality in the different time periods. Results — For undisplaced FFNs treatment with hemiarthroplasty increased from 2.1% to 9.7% during the study period. For displaced FFNs treatment with arthroplasty increased from 56% to 93%. The use of intramedullary nails increased from 9.1% to 26% for stable 2-fragment (AO/OTA A1) trochanteric fractures, from 15% to 33% for multifragment (AO/OTA A2) trochanteric fractures, and from 27% to 61% for intertrochanteric fractures (AO/OTA A3)/subtrochanteric fractures. Compared with the first time period the adjusted 1-year RR for reoperation was 0.43 (95% CI: 0.37–0.49) for displaced FFNs in the last time period. The adjusted 1-year mortality in the last time period was lower for all fractures (RR: 0.87 (0.83–0.91)), displaced FFNs (RR: 0.86 (0.80–0.93)), AO/OTA A1 trochanteric fractures (RR: 0.79 (0.71–0.88)), and AO/OTA A2 trochanteric fractures (RR: 0.87 (0.77–0.98)) when compared with the first study period. Interpretation — Hip fracture treatment in Norway has improved: The risk of reoperation and the 1-year mortality after displaced femoral neck fractures have decreased over a 10-year period. National registration is useful to monitor trends in treatment and outcomes after hip fractures.

Postoperative start compared to preoperative start of low-molecular-weight heparin increases mortality in patients with femoral neck fractures

Background and purpose — Controversies exist regarding thromboprophylaxis in orthopedic surgery. Using data in the nationwide Norwegian Hip Fracture Register (NHFR) with postoperative death and reoperation in the first 6 months after surgery as endpoints in the analyses, we determined whether the thromboprophylaxis in patients who undergo hemiarthroplasty for femoral neck fracture should start preoperatively or postoperatively. Patients and methods — After each operation for hip fracture in Norway, the surgeon reports information on the patient, the fracture, and the operation to the NHFR. Cox regression analyses were performed with adjustments for age, ASA score, gender, type of implant, length of surgery, and year of surgery. Results — During the period 2005–2014, 25,019 hemiarthroplasties as treatment for femoral neck fractures were reported to the registry. Antithrombotic medication was given to 99% of the patients. Low-molecular-weight heparin predominated with dalteparin in 57% of the operations and enoxaparin in 41%. Only operations with these 2 drugs and with known information on preoperative or postoperative start of the prophylaxis were included in the analyses (n = 20,241). Compared to preoperative start of thromboprophylaxis, postoperative start of thromboprophylaxis gave a higher risk of death (risk ratio (RR) = 1.13, 95% CI: 1.06–1.21; p < 0.001) and a higher risk of reoperation for any reason (RR =1.19, 95% CI: 1.01–1.40; p = 0.04), whereas we found no effect on reported intraoperative bleeding complication or on the risk of postoperative reoperation due to hematoma. The results did not depend on whether the initial dose of prophylaxis was the full dosage or half of the standard dosage. Interpretation — Postoperative start of thromboprophylaxis increased the mortality and risk of reoperation compared to preoperative start in femoral neck fracture patients operated with hemiprosthesis. The risks of bleeding and of reoperation due to hematoma were similar in patients who received low-molecular-weight heparin preoperatively and in those who received it postoperatively.

A survivorship study of 838 total elbow replacements: a report from the Norwegian Arthroplasty Register 1994-2016

BACKGROUND The aim of this study was to present the long-term survivorship (20 years) of total elbow arthroplasty (TEA) for a relatively large population and to compare different prosthesis brands and patient subgroups. METHODS Between 1994 and 2017, a total of 838 primary TEAs were reported to the Norwegian Arthroplasty Register. Implant survival was calculated using the Kaplan-Meier method. Risk differences were examined using Cox regression analyses and exact Cox regression for rare events. We compared the survivorship of the 8 most frequently used implant brands, the different diagnoses leading to TEA, and the influence of the fixation technique. RESULTS The overall 5-, 10-, 15-, and 20-year survival rates for all elbow arthroplasties were 92%, 81%, 71%, and 61%, respectively. Risk factors for revision were a diagnosis of sequelae after trauma and cementless fixation of the ulna component. There were some differences between the implant brands. The Norway prostheses had higher survival compared with the Kudo after 15 years of follow-up (78% and 66%, respectively; P < .001). Among the implants with shorter follow-up, the IBP and NES had inferior survivorship compared with the Norway. The frequently used Discovery had promising survivorship up to 5 years. The most frequent reason for revision surgery was aseptic loosening, followed by defective polyethylene, infection, and dislocation. The revision causes were to some degree implant specific. CONCLUSION Fairly good results in terms of prosthesis survival were obtained with TEA, although results were poorer than for knee and hip arthroplasties.

Pelvic irradiation does not increase the risk of hip replacement in patients with gynecological cancer. A cohort study based on 8,507 patients

Background and purpose — Long-term survivors of cancer can develop adverse effects of the treatment. 60% of cancer patients survive for at least 5 years after diagnosis. Pelvic irradiation can cause bone damage in these long-term survivors, with increased risk of fracture and degeneration of the hip. Patients and methods — Analyses were based on linkage between the Cancer Registry of Norway (CRN) and the Norwegian Arthroplasty Register (NAR). All women who had been exposed to radiation for curative radiotherapy of gynecological cancer (40–60 Gy for at least 28 days) were identified in the CRN. Radiotherapy had been given between 1998 and 2006 and only patients who were irradiated within 6 months of diagnosis were included. The control group contained women with breast cancer who had also undergone radiotherapy, but not to the pelvic area. Fine and Gray competing-risk analysis was used to calculate subhazard-rate ratios (subHRRs) and cumulative incidence functions (CIFs) for the risk of having a prosthesis accounting for differences in mortality. Results — Of 962 eligible patients with gynecological cancer, 26 (3%) had received a total hip replacement. In the control group without exposure, 253 (3%) of 7,545 patients with breast cancer had undergone total hip replacement. The 8-year CIF for receiving a total hip replacement was 2.7% (95% CI: 2.6–2.8) for gynecological cancer patients and 3.0% (95% CI: 2.95–3.03) for breast cancer patients; subHRR was 0.80 (95% CI: 0.53–1.22; p = 0.3). In both groups, the most common reason for hip replacement was idiopathic osteoarthritis. Interpretation — We did not find any statistically significantly higher risk of undergoing total hip replacement in patients with gynecological cancer who had had pelvic radiotherapy than in women with breast cancer who had not had pelvic radiotherapy.

Long-term risk of receiving a total hip replacement in cancer patients

AIM To investigate whether cancer patients have an increased risk of receiving a total hip replacement compared to the standard population of Norway. MATERIALS AND METHODS By linking of The Cancer Register of Norway and The Norwegian Arthroplasty Register we obtained information on cancer diagnoses (type, date of diagnosis), total hip arthroplasties and date of death for all patients living in Norway. This includes 741,901 patients categorized into three groups: 652,197 patients with at least one cancer diagnosis but no hip arthroplasties, 72,469 patients with at least one hip arthroplasty but no cancer diagnosis and 17,235 patients who have at least one cancer diagnosis and at least one hip arthroplasty. Within this latter group, 8563 individuals had been diagnosed with cancer prior to a total hip arthroplasty. Statistical methods applied in this study were Cox interval censored regression models and standardized incidence ratios (SIR). RESULTS Cancer patients had a slightly increased risk of receiving a total hip arthroplasty compared to the Norwegian population (SIR=1.15 (95% CI, 1.12-1.17)). For primary tumours located cranially to the pelvic area there was no significant increase in risk for hip arthroplasty. An exception was breast cancer (SIR=1.13 (95% CI 1.08-1.18)). Cancer located in the pelvic region (SIR=1.20 (95% CI 1.16-1.24)), malignant lymphoma (SIR=1.30 (95% CI 1.15-1.46)) and leukaemia (SIR=1.17 (95% CI 1.01-1.34)) had an increased risk for receiving a total hip arthroplasty. CONCLUSION Cancer survivors, mainly those with pelvic and lympho-hematological malignancies, have a small statistically significant increase in risk for receiving total hip arthroplasty.