Measuring long radiographs affects the positioning of femoral components in total knee arthroplasty: a randomized controlled trial.

INTRODUCTION: The aim of this study was to investigate if preoperative measurements of the femoral valgus angle (FVA) affected the mechanical alignment, individual component positions and clinical outcome in total knee arthroplasty (TKA). METHODS: 120 patients were randomized into two groups. In one group (control), a fixed FVA for the intramedullary femoral guide was set at 7°, whereas in the other group (measured) FVA was measured preoperatively on long hip-knee-ankle radiographs, and the angle for the distal femoral cut was set accordingly. Preoperatively and 1 year after TKA, range of motion (ROM) and Knee Society Score (KSS) were assessed. Postoperatively, the coronal alignments of the components and the mechanical alignment were measured comparing the rate of outliers which deviated more than 3° from the neutral mechanical axis. RESULTS: 104 patients remained for the radiological analysis (52 in each group). There were no significant differences either in the mean preoperative or postoperative mechanical alignment, or femoral or tibial component alignment; also, there were no differences in the number of postoperative mechanical axis or tibial component alignment outliers. However, the number of femoral component alignment outliers was significantly higher in the control group. 97 patients were available for clinical outcome analysis. Preoperatively, the groups did not differ significantly with respect to KSS or ROM. The postoperative ROM and KSS functional subscale scores were similar between the groups. However, there was slightly but significantly better postoperative KSS objective subscale score in the measured group. CONCLUSIONS: Preoperative FVA measurement and following femoral distal cut adjustments did not affect overall leg alignment postoperatively, while positioning of femoral component was improved together with minor improvements in objective KSS subscale scores.

Excellent long-term results of the Müller acetabular reinforcement ring in primary total hip arthroplasty: A prospective study on radiology and survival of 321 hips with a mean follow-up of 11 years.

BACKGROUND AND PURPOSE: The original Müller acetabular reinforcement ring (ARR) shows favorable medium-term results for acetabular reconstruction in total hip arthroplasty, where it is used when the acetabular bone stock is deficient. However, there are no data regarding long-term survival of the device. We therefore investigated long-term survival and analyzed radiological modes of failure. PATIENTS AND METHODS: Between 1984 and 2002, 321 consecutive primary arthroplasties using an ARR were performed in 291 patients. The mean follow-up time was 11 (0-25) years, and 24 hips were lost to follow-up. For survival analysis, we investigated 321 hips and the end of the follow-up was the date of revision, date of death, or the last patient contact date with implant still in situ. Radiological assessment was performed for 160 hips with a minimum of 10 years of follow-up and with radiographs of sufficient quality. It included evaluation of osteolysis, migration, and loosening. RESULTS: 12 ARR THAs were revised: 1 isolated ARR revision for aseptic loosening, 4 revisions of the ARR and the stem for aseptic loosening, 6 for infection, and 1 for recurrent dislocation. The cumulative revision rate for all components, for any reason, at 20 years was 15% (95% CI: 10-22), while for the ARR only it was 7% (95% CI: 4-12) for any reason and 3.4% (95% CI: 1-9) for aseptic loosening. 21 (13%) of 160 ARR THAs examined had radiological changes: 7 had osteolysis but were not loose, and 14 were radiologically loose but were not painful and not revised. INTERPRETATION: Our data suggest that the long-term survival of the ARR is excellent.

Fragility Fractures in Patients with Rheumatoid Arthritis and Osteoarthritis Compared with the General Population.

OBJECTIVE: To determine the rate ratios of hip and distal radius fractures in patients with rheumatoid arthritis (RA), hip osteoarthritis (OA), and knee OA. METHODS: Cohort study using healthcare data (1998-2012) covering the entire population of the Skåne region of Sweden. RESULTS: We found an increased rate of hip fracture in both female [standardized fracture rate ratio (SFR) 1.54, 95% CI 1.40-1.70] and male patients with RA (SFR 1.81, 95% CI 1.51-2.17). The hip fracture rate in female OA was reduced by 10-20%, and trochanteric fracture tended to have a higher rate ratio compared with the cervical. CONCLUSION: The 50-80% increased rate of hip fracture adds to the total burden of RA while the shifted distribution of cervical/trochanteric fractures in OA is in support of subchondral bone alterations.

Moderate varus/valgus malalignment after total knee arthroplasty has little effect on knee function or muscle strength.

BACKGROUND AND PURPOSE: Postoperative muscle strength and component alignment are important factors affecting functional results after total knee arthroplasty (TKA). We are not aware of any studies that have investigated the relationship between them. We therefore investigated whether coronal malalignment of the mechanical axis and/or of individual implant components would affect knee muscle strength and function 1 year after TKA surgery. PATIENTS AND METHODS: We included 120 consecutive osteoarthritis (OA) patients admitted for TKA. Preoperative active range of motion (ROM) of the knee, patient age, sex, and BMI were recorded and the Knee Society score (KSS) and knee joint extensor/flexor muscle strength were assessed. At 1-year follow-up, the mechanical and coronal component alignment was measured from a postoperative long standing radiograph, and ROM, KSS, and muscle strength measurements were taken in 91 patients. Functional outcome and muscle strength measurements were compared between normally aligned and malaligned TKA groups. RESULTS: 29 of 91 TKAs were malaligned, i.e. they deviated more than 3° from the neutral mechanical axis. 18 femoral components and 15 tibial components were malaligned. Before surgery, the malaligned and normally aligned groups were similar regarding sex distribution, BMI, ROM, KSS, and muscle strength. At the 1-year follow-up, the differences between the groups regarding knee joint function and muscle strength were small, not statistically significant, and barely clinically relevant. INTERPRETATION: Moderate varus/valgus malalignment of the mechanical axis or of individual components has no relevant clinical effect on function or muscle strength 1 year after TKA surgery.

The analysis of posterior soft tissue repair durability after total hip arthroplasty in primary osteoarthritis patients.

BACKGROUND AND PURPOSE: The posterior soft tissue repair is 1 of the preventing factors for dislocation after total hip arthroplasty (THA).The aim of our study was to analyse THA patients with posterior soft tissue repair in terms of suture durability, time of suture failure and correlate the changes in leg length and offset postoperatively to suture durability. METHODS: A total of 37 consecutive THA patients operated for osteoarthritis were included in the study. The posterior repair included reattaching the piriformis, conjoined tendons and posterior capsule to the greater trochanter through 2, 2 mm drill holes with 2 grasping stitches. A metal indicator wire was stitched into the piriformis tendon at distance of 1 cm from the greater trochanter after the prosthesis had been implanted and the joint reduced. Anteroposterior radiographs were taken immediately after the patients returned from the operating theatre to the intensive care unit, the next day after mobilisation, and at the 5th day of stay and at 3 months postoperatively. RESULTS: Out of 37 THA hips, 6 (16%) had failed immediately after surgery, 25 (68%) at the 1st postoperative day after mobilisation, 2 (5%) at the 5th postoperative day, and 1 (3%) repairs had failed at 3 months after THA. In the remaining 3 hips no failure occurred. INTERPRETATION: We conclude that posterior soft tissue repair in THA often fails and suggest that new posterior soft tissue repair methods be developed.

Size of cup affects the anterior capsular distance in total hip arthroplasty, as measured with ultrasound.

BACKGROUND: Previously was found that sonography is a reliable method to measure a capsular distance in total hip arthroplasty hips. The aim of our current study was to investigate the relation between the implanted size of the cup and the anterior capsular distance, as measured with ultrasound one year after THA. METHODS: 50 osteoarthritis (OA) patients operated on with total hip arthroplasty one year before were included in the study and the anterior capsular distance was measured sonographically. Patients were grouped with respect to cup size. The correlation between the implanted cup size and capsular distance was determined. RESULTS: The mean capsular distance in the whole group was 1.37 (SD 0.19) cm. The mean capsular distance in the group with small cups was 1.27 (SD 0.13) cm, in large cups it was 1.45 (SD 0.20) cm, p = 0.02. Spearman correlation analysis showed a statistically significant correlation between a greater capsular distance and the larger size of the cup (r = 0.5, p < 0.0001). CONCLUSION: The greater capsular distance in successful THA hips is affected by cup size. We propose that this should be considered when evaluating sonography of the anterior capsular distance after THA.

Dynamics of femoral bone remodelling in well fixed total hip arthroplasty. A 20-year follow-up of 20 hips.

The aim of our study was to investigate the dynamics of cortical thinning around well fixed cemented Muller straight stems without osteolysis at different time periods during long term follow-up. We investigated patients operated on for osteoarthritis with a cemented Muller straight stem, all with more than 15 years follow-up and no radiological signs of osteolysis. Cortical thinning in 20 THA hips (19 patients) followed for a mean of 20 (16 to 22) years was measured medially and laterally at six levels from the first postoperative, five, 10 years and the last follow-up x-rays. Sixty percent of observed cortical thinning occurred during the first five postoperative years, which was more evident proximally. We conclude that significantly greater cortical bone loss occurs around cemented Muller straight stems during the first five years, than is seen subsequently. We feel that this is a non-pathological process mainly related to the Muller straight stem.

A comparison of outcomes and dislocation rates using dual articulation cups and THA for intracapsular femoral neck fractures.

Total hip arthroplasty for intracapsular femoral neck fractures (FNF) is associated with a greater risk of dislocation. Dual articulation systems in this group of patients may provide better implant stability and a reduced dislocation rate. The aim of our study was to investigate FNF patients treated with dual articulation cups (DAC) and conventional THA and compare their clinical results at four months and one year after surgery. Our study compared femoral neck fracture patients treated with either DAC or conventional THA during two different time periods. Before surgery and during follow-up, the patients answered questions regarding their mobility, pain and usage of walking aids. Additionally at four-month and one-year follow-ups EQ-5D and HOOS questionnaires were applied for those patients qualifying for functional and quality of life analysis. Out of 125 femoral neck fracture patients 58 were treated with DAC and 67 with conventional THA. At four months and one year follow-up the HOOS and EQ-5D results did not differ significantly between DAC and conventional THA. Five hips in the THA group were revised for recurrent dislocation and two had a single dislocation. One year after surgery, the functional result of DAC and conventional THA are comparable but DAC have a lower risk of dislocation.

Long-term femoral bone remodeling after cemented hip arthroplasty with the Müller straight stem in the operated and nonoperated femora.

We investigated the cortical bone changes in 35 patients with total hip arthroplasty operated on only for osteoarthritis with more than 10 years of follow-up and with nonrevised femoral components and without radiologic signs of loosening. The mean follow-up was 16 ± 5 years. The thicknesses of femoral cortices were measured medially and laterally at 6 levels from the first postoperative and the last follow-up x-rays. A comparison with 10 patients who had a nonoperated contralateral hip was performed. We found a significant decrease in cortical thicknesses in total hip arthroplasty. The cortical thinning was significant at all periprosthetic levels but less expressed distally. Prosthetic femora were associated with greater cortical thinning as compared with the contralateral nonoperated femora, exceeding that caused by natural aging.

The short rotators do not influence capsular compliance or pain in severe hip osteoarthritis. A randomised controlled trial.

A randomised controlled trial was performed to investigate if the short rotators affected the compliance of the capsule in osteoarthritis (OA). 68 OA patients admitted for total hip arthroplasty (THA) were randomised to have their compliance estimated during surgery with either their short rotators intact or released. Radiographic severity of OA, range of motion and pain were assessed in the affected hip before surgery. There was no significant difference in the compliance of the capsule whether the short rotators were intact or released (p= 0.5). Furthermore, there was no significant correlation between pain and capsular compliance (p=0.4 and p=0.5). We found no significant effect of the short rotators on compliance of the hip joint capsule, and no significant correlation between pain and capsular compliance.

Posterior soft tissue repair in total hip arthroplasty: a randomized controlled trial.

Posterior soft tissue repair is a well-known procedure in total hip arthroplasty (THA). Many reports have shown the advantage of posterior soft tissue repair in reducing the dislocation rate; however, we were unable to find any randomized trials in the literature. This article describes a randomized trial performed to investigate the effect of posterior soft tissue repair on the dislocation rate after 298 THAs in 291 patients. Preoperatively, patients were randomized into 2 groups: posterior soft tissue repair after insertion of the components, or no posterior soft tissue repair. One year postoperatively, 12 patients had died and 10 were lost to follow-up, leaving 276 THAs in 265 patients for analysis. A posterior soft tissue repair had been performed in 134 and no repair in 141 THA. One year postoperatively, 3 dislocations (2%) had occurred in the repaired group and 7 in the unrepaired group (5%); the difference was not significant (P=.3). There were 2 sciatic nerve palsies in the repaired group, 1 of which was directly related to the posterior soft tissue repair.In this randomized, controlled trial of 276 THAs followed for 1 year, there was a tendency for a lower dislocation rate, although not statistically significant, when a posterior repair was performed. If reattaching the posterior tendons, it should be performed with caution with respect to the sciatic nerve.

Dual mobility cup reduces dislocation rate after arthroplasty for femoral neck fracture.

BACKGROUND: Hip dislocation after arthroplasty for femoral neck fractures remains a serious complication. The aim of our study was to investigate the dislocation rate in acute femoral neck fracture patients operated with a posterior approach with cemented conventional or dual articulation acetabular components. METHODS: We compared the dislocation rate in 56 consecutive patients operated with conventional (single mobility) cemented acetabular components to that in 42 consecutive patients operated with dual articulation acetabular components. All the patients were operated via posterior approach and were followed up to one year postoperatively. RESULTS: There were 8 dislocations in the 56 patients having conventional components as compared to no dislocations in those 42 having dual articulation components (p = 0.01). The groups were similar with respect to age and gender distribution. CONCLUSIONS: We conclude that the use of a cemented dual articulation acetabular component significantly reduces the dislocation rates in femoral neck fracture patients operated via posterior approach.

Delayed hospitalization increases mortality in displaced femoral neck fracture patients.

BACKGROUND AND PURPOSE: Reports regarding the relationship between delayed surgery and mortality in femoral neck fracture patients are contradictory. We could not find any study in the literature investigating delayed arrival to hospital and delayed surgery as separate factors affecting mortality in femoral neck fracture patients, which was the purpose of our study. PATIENTS AND METHODS: We analyzed 265 consecutive patients with displaced femoral neck fractures. We recorded the time period from trauma to admission, and to surgery, and correlated it to mortality during the first postoperative year. RESULTS: We found that arrival within 6 hours had 0.4 times (CI 0.2-0.8) reduction of the risk of death within 1 year compared to those who arrived later, whereas delayed surgery after admission did not have a statistically significant effect on mortality. INTERPRETATION: Femoral neck fracture patients who arrived at hospital 6 hours or later after the trauma had increased mortality.

Introduction of total knee arthroplasty in Lithuania: Results from the first 10 years.

BACKGROUND AND PURPOSE: We have previously reported that the first 10 years of hip arthroplasty in Lithuania resulted in a higher cumulative revision rate than that observed in Sweden. We thus compared the corresponding results after introduaction of total knee replacement in Lithuania. METHODS: The 10-year revision rate for the first 595 primary ScanKnee arthroplasties inserted in Klaipeda, Lithuania, was compared to that for the first 1,280 ScanKnee primary arthroplasties inserted in Sweden. As in the hip replacement study, only patients with osteoarthritis (OA) were included. Primary knee arthroplasties without patellar resurfacing were included, and the endpoint was revision for any reason other than addition of a patellar component. RESULTS: We found that the cumulative revision rate was not statistically significantly different between the groups. The revision pattern was different, however, and we observed 24 isolated patellar component additions in Sweden, but none in Klaipeda. INTERPRETATION: Contrary to the results of our previous hip arthroplasty study, the cumulative revision rate after total knee arthroplasty was similar in the two groups. This suggests that compared to hip arthroplasty, the outcome of total knee arthroplasty was less dependent on surgical experience. The large difference regarding isolated patellar component additions may be explained by long-term accumulation of severe OA cases in Lithuania. To patients subject to a newly introduced surgical treatment offering great improvement in quality of life, patellofemoral pain may be a minor problem. Furthermore, patellar problems may not have seemed particularly relevant for the surgeons, considering the disability of other patients waiting to be treated.

Short rotator tendons do not increase intracapsular pressure in severe osteoarthritic hips.

BACKGROUND: While a relation between pain and intracapsular pressure in the hip joint has previously been reported by some of the present authors, a newly published study including patients with severe osteoarthritis was not able to confirm this finding. This stimulated us to investigate the role of short rotators in relation to intracapsular pressure and pain in osteoarthritic hips. METHODS: We measured the intracapsular hydrostatic pressure peroperatively in 25 total hip arthroplasty patients with severe osteoarthritis in various positions of the hip joint before and after short rotator release, and correlated these pressures to pain. RESULTS: Release of the short rotators did not change the intracapsular pressure in any position except in 45 degrees flexion, in which the pressure increased (p = 0.002). We found no correlation between intracapsular pressure and pain before or after short rotator release. CONCLUSION: We could not show that the rotators directly affected the pressure nor could we find a relation between pressure and pain.

Conventional drainage versus four hour clamping drainage after total knee arthroplasty in severe osteoarthritis: a prospective, randomised trial.

Total knee replacement in severe osteoarthritis usually requires extensive soft tissue releases often associated with considerable bleeding. In a prospective, randomised trial we compared postoperative conventional suction drainage versus four hour clamping drainage in 60 patients undergoing total knee arthroplasty for severe osteoarthritis. We compared blood loss, number of transfusions, postoperative complications and knee function and found significantly less postoperative blood loss through the drains (p < 0.001), and fewer blood transfusions (p = 0.09) were needed in the clamped group. We conclude that clamping drainage after total knee arthroplasty in severe osteoarthritis reduces blood loss through the drains and the need for blood transfusions.

Effect of femoral head size on polyethylene wear and synovitis after total hip arthroplasty: a sonographic and radiographic study of 39 patients.

BACKGROUND AND PURPOSE: The role of synovitis and high fluid pressure in the loosening process after total hip arthroplasty has gained increasing attention. We investigated the correlation between head size, polyethylene wear, and capsular distention. PATIENTS AND METHODS: We analyzed 39 unrevised, radiographically stable hips that had been operated with 28 or 32 mm femoral heads 10 years earlier because of osteoarthritis. We evaluated radiographic signs of loosening, linear and volumetric polyethylene wear, body mass index, activity level, and age. Sonographic examination was performed to measure capsular distance i.e. the distance between the prosthetic femoral neck and the anterior capsule. RESULTS: Linear wear was 0.09 mm/year and 0.18 mm/year in the 28 mm and 32 mm groups, respectively (p < 0.001). The volumetric wear was 51 mm(3)/year and 136 mm(3)/year (p < 0.001) and the capsular distance was 13 mm and 17 mm, respectively (p < 0.001). There was a correlation between linear wear (r = 0.54), volumetric wear (r = 0.62), and capsular distance (p < 0.001). INTERPRETATION: Wear was greater for the larger femoral head and was correlated to capsular distension.