To what extent can soft-tissue releases improve hip displacement in cerebral palsy?

Background and purpose — Hip displacement is frequent in nonambulatory children with cerebral palsy (CP) and treatment is controversial. This prospective study assesses the effectiveness of soft-tissue releases to treat hip subluxation, analyses prognostic factors for outcome, and identifies time to failure in hips with poor outcome.

Patients and methods — 37 children (16 girls) with hip subluxation were recruited from the population-based screening program for children with CP in Norway. They had consecutively undergone soft-tissue releases (bilateral tenotomies of adductors and iliopsoas) at a mean age of 5.0 (2.8–7.2) years. Functional classification was Gross Motor Function Classification System (GMFCS) level III in 9 children, level IV in 10, and level V in 18 children. The outcome was termed good if the patient had not undergone further hip surgery and if the migration percentage (MP) of the worst hip at the latest follow-up was <50%. The mean follow-up time was 7.3 (5.1–9.8) years.

Results — The outcome was good in all the ambulatory children and in 17 of 28 of the nonambulatory children. The only independent preoperative risk factor for poor outcome was MP ≥50%. The mean time to failure was 2.2 (1–5) years postoperatively and the reasons for failure were insufficient initial correction and later deterioration of displacement.

Interpretation — Bilateral soft-tissue release is recommended in both ambulatory and nonambulatory children with hip sub­luxation. The operation should be performed before the hip displacement reaches 50%.     

Cemented total hip replacement in patients under 55 years

Background and purpose — About 86,000 total hip replacements (THR) have been registered in patients under 55 years in the National Joint Registry of England and Wales (NJR). The use of uncemented implants has increased, despite their outcomes not having been proven to be significantly better than cemented implants in this registry. We determined the implant survivorship and functional outcomes of cemented THR in patients under 55 years at a minimum follow-up of 22 years.

Patients and methods — 104 hips in 100 patients were included in this prospective study. Functional outcome was assessed using the Harris Hip Score and radiographs were assessed for implant failure and “at risk” of failure. Kaplan–Meier survivorship analysis was performed.

Results — 89% of hips showed good to excellent results at final follow-up with a mean Harris Hip Score of 88 at a mean follow-up of 25 years. Revision was performed in 3/104 hips. 14 acetabular components and 4 femoral components were “at risk” of failure. The survivorship at minimum 22 years with revision for any reason as the end-point was 97% (95% CI 95–98).

Interpretation — Cemented hip replacements perform well in young patients with good long-term functional and radiographic outcomes.     

Comorbidity does not predict long-term mortality after total hip arthroplasty

Background and purpose — In-hospital death following total hip arthroplasty (THA) is related to comorbidity. The long-term effect of comorbidity on all-cause mortality is, however, unknown for this group of patients and it was investigated in this study.

Patients and methods — We used data from the Swedish Hip Arthroplasty Register, linked to the National Patient Register from the National Board of Health and Welfare, for patients operated on with THA in 1999–2012. We identified 120,836 THAs that could be included in the study. We evaluated the predictive power of the Charlson and Elixhauser comorbidity indices on mortality, using concordance indices calculated after 5, 8, and 14 years after THA.

Results — All comorbidity indices performed poorly as predictors, in fact worse than a base model with age and sex only. Elixhauser was, however, the least bad choice and it predicted mortality with concordance indices 0.59, 0.58, and 0.56 for 5, 8, and 14 years after THA.

Interpretation — Comorbidity indices are poor predictors of long-term mortality after THA.     

Risk of further surgery on the same or opposite side and mortality after primary total hip arthroplasty: A multi-state analysis of 133,654 patients from the Swedish Hip Arthroplasty Register

Background and purpose — The hip-related timeline of patients following a total hip arthroplasty (THA) can vary. Ideally patients will live their life without need for further surgery; however, some will undergo replacement on the contralateral hip and/or reoperations. We analyzed the probability of mortality and further hip-related surgery on the same or contralateral hip.

Patients and methods — We performed a multi-state survival analysis on a prospectively followed cohort of 133,654 Swedish patients undergoing an elective THA between 1999 and 2012. The study used longitudinally collected information from the Swedish Hip Arthroplasty Register and administrative databases. The analysis considered the patients’ sex, age, prosthesis type, surgical approach, diagnosis, comorbidities, education, and civil status.

Results — During the study period patients were twice as likely to have their contralateral hip replaced than to die. However, with passing time, probabilities converged and for a patient who only had 1 non-revised THA at 10 years, there was an equal chance of receiving a second THA and dying (24%). It was 8 times more likely that the second hip would become operated with a primary THA than that the first hip would be revised. Multivariable regression analysis reinforced the influence of age at operation, sex, diagnosis, comorbidity, and socioeconomic status influencing state transition.

Interpretation — Multi-state analysis can provide a comprehensive model of further states and transition probabilities after an elective THA. Information regarding the lifetime risk for bilateral surgery, revision, and death can be of value when discussing the future possible outcomes with patients, in healthcare planning, and for the healthcare economy.     

Lack of evidence—the anti-stepwise introduction of metal-on-metal hip replacements

Background and purpose — Orthopedics and especially joint replacement surgery have had more than their fair share of unsuccessful innovations that have violated widely endorsed principles for the introduction of new surgical innovations. We aimed to investigate (1) the trends in the use of the Birmingham Hip Resurfacing (BHR), the ASR hip resurfacing (ASR HRA) and the ASR XL total hip replacement (ASR XL THR) system with very different market approval processes and (2) whether their use was corroborated by clinical trials published in the peer-reviewed literature.

Methods — The literature was searched for any clinical studies that reported outcomes of the BHR, ASR HRA and ASR XL THRs. Data from 7 national hip arthroplasty registers were collected and the number of annually implanted devices was matched to those reported in the literature.

Results — The cumulative number of implanted and published BHRs grew proportionally with a small lag. The growth of implanted BHRs started to decline at the same time as the ASR HR was introduced. With regard to ASR HRAs, the cumulative proportion of implanted hips and those included in the published studies grew disproportionately after the introduction of the ASR in 2003. For ASR XL THRs, the disproportionality is even higher.

Interpretation — The adoption of ASR hip replacements did not follow the proposed stepwise introduction of orthopedic implants. The adoption and use of any new implant should follow a strict guideline and algorithm even if the theoretical basis or the results of preclinical studies are excellent.     

Good inter- and intraobserver reliability for assessment of the slip angle in 77 hip radiographs of children with a slipped capital femoral epiphysis

Background and purpose — The decision on and the outcome of treatment for a slipped capital femoral epiphysis (SCFE) depend on the severity of the slip. In 2015, web-based registration was introduced into the Swedish Pediatric Orthopedic Quality (SPOQ) register. To determine whether the inclusion of commonly used methods in Sweden for radiographic measurement of SCFE (the calcar femorale [CF] method and the Billing method) is justified, we measured the inter- and intraobserver reliability of these 2 measurements. We also evaluated the internationally more commonly used head-shaft angle (HSA) method.

Material and methods — 4 observers with different levels of experience with radiographic measurements analyzed 77 routine preoperative hip radiographs of children with SCFE. Inter- and intraobserver reliability was evaluated.

Results — The interobserver reliability analysis for the 4 observers showed for CF an ICC of 0.99 (CI 0.97–0.99) and for Billing an ICC of 0.99 (CI 0.98–0.99). The interobserver reliability analysis for 2 observers showed for HSA an ICC of 0.98 (CI 0.97–0.99).

Intraobserver reliability (2 observers) showed a mean difference below 1° for all 3 methods and with a 95% limit of agreement not exceeding ±6.8°.

Interpretation — We found good reliability for both intra- and interobserver measurements of all 3 methods used for the assessment of the slip angle on routine preoperative lateral hip radiographs.     

Patient-reported outcome after total hip arthroplasty: comparison between lateral and posterior approach

Background and purpose — Criticism of the lateral approach (LA) for hip arthroplasty is mainly based on the risk of poor patient-reported outcomes compared to the posterior approach (PA). However, there have been no controlled studies comparing patient-reported outcomes between them. In this randomized controlled trial, we tested the hypothesis that patient-reported outcomes are better in patients who have undergone total hip arthroplasty (THA) with PA than in those who have undergone THA with LA, 12 months postoperatively.

Patients and methods — 80 patients with hip osteoarthritis (mean age 61 years) were randomized to THA using PA or the modified direct LA. We recorded outcome measures preoperatively and 3, 6, and 12 months postoperatively using the Hip Disability and Osteoarthritis Outcome Score–Physical Function Short Form (HOOS-PS) as the primary outcome. Secondary outcomes were HOOS-Pain, HOOS-Quality-Of-Life, EQ-5D, UCLA Activity Score, and limping.

Results — We found no statistically significant difference in the improvements in HOOS-PS between the treatment groups at 12-month follow-up. All secondary outcomes showed similar results except for limping, where PA patients improved significantly more than LA patients.

Interpretation — Contrary to our hypothesis, patients treated with PA did not improve more than patients treated with LA regarding physical function, pain, physical activity, and quality of life 12 months postoperatively. However, limping was more pronounced in the LA patients.     

Arthroplasty for tenosynovial giant cell tumors

Background and purpose — Tenosynovial giant cell tumors (t-GCTs) can behave aggressively locally and affect joint function and quality of life. The role of arthroplasty in the treatment of t-GCT is uncertain. We report the results of arthroplasty in t-GCT patients.

Patients and methods — t-GCT patients (12 knee, 5 hip) received an arthroplasty between 1985 and 2015. Indication for arthroplasty, recurrences, complications, quality of life, and functional scores were evaluated after a mean follow-up time of 5.5 (0.2–15) years.

Results — 2 patients had recurrent disease. 2 other patients had implant loosening. Functional scores showed poor results in almost half of the knee patients. 4 of the hip patients scored excellent and 1 scored fair. Quality of life was reduced in 1 or more subscales for 2 hip patients and for 5 knee patients.

Interpretation — In t-GCT patients with extensive disease or osteoarthritis, joint arthroplasty is an additional treatment option. However, recurrences, implant loosening, and other complications do occur, even after several years.     

Posterior approach compared to direct lateral approach resulted in better patient-reported outcome after hemiarthroplasty for femoral neck fracture

Background and purpose — Hemiarthroplasty (HA) is the most common treatment for displaced femoral neck fractures in many countries. In Norway, there has been a tradition of using the direct lateral surgical approach, but worldwide a posterior approach is more often used. Based on data from the Norwegian Hip Fracture Register, we compared the results of HA operated through the posterior and direct lateral approaches regarding patient-reported outcome measures (PROMs) and reoperation rate.

Patients and methods — HAs due to femoral neck fracture in patients aged 60 years and older were included from the Norwegian Hip Fracture Register (2005–2014). 18,918 procedures were reported with direct lateral approach and 1,990 with posterior approach. PROM data (satisfaction, pain, quality of life (EQ-5D), and walking ability) were reported 4, 12, and 36 months postoperatively. The Cox regression model was used to calculate relative risk (RR) of reoperation.

Results — There were statistically significant differences in PROM data with less pain, better satisfaction, and better quality of life after surgery using the posterior approach than using the direct lateral approach. The risk of reoperation was similar between the approaches.

Interpretation — Hemiarthroplasty for hip fracture performed through a posterior approach rather than a direct lateral approach results in less pain, with better patient satisfaction and better quality of life. The risk of reoperation was similar with both approaches.     

The Cox model is better than the Fine and Gray model when estimating relative revision risks from arthroplasty register data

Background and purpose — Analysis of the revision-free survival of knee and hip prostheses has traditionally been performed using Kaplan–Meier analysis and Cox regression. The competing risk problem that is related to patients who die during follow-up has recently been increasingly discussed, not least with regard to the problem of choosing a suitable statistical method for the analysis. We compared the results from analyses of Cox models and Fine and Gray models.

Methods — We used data simulation based on parameter estimates from the Swedish Knee Arthroplasty Register and assessed hypothetical effects of the studied risk factors.

Results — The Cox model provided more adequate results.

Interpretation — The parameter estimates from the Fine and Gray model can be misleading if interpreted in terms of relative risk.     

Reduced risk of reoperation after treatment of femoral neck fractures with total hip arthroplasty

Background and purpose — Femoral neck fractures (FNFs) are commonly treated with some kind of arthroplasty, but evidence on whether to use hemiarthroplasty (HA) or total hip arthroplasty (THA) is lacking. HA reduces the risk of dislocation, but may lead to acetabular erosion. THA implies longer surgery and increased bleeding. THA may result in better function and health-related quality of life, but evidence is contradictory. We compared HA and THA and in terms of revision, reoperation and death.

Patients and methods — Data were extracted from the Swedish Hip Arthroplasty Register for 11,253 patients with acute FNF receiving cemented HA or THA during 2008–2012. 2,902 patients with THA were matched by propensity score matching with as many patients with HA based on age, sex, BMI, and ASA classification. We used competing risks survival regression with reoperation or death and revision or death as endpoints.

Results — THA patients had significantly reduced risk of revision (absolute risk reduction 0.51; 95% CI 0.39–0.67) and reoperation (0.58; 0.46–0.74). THA was associated with an almost 50% reduced mortality (risk ratio as competing risk for reoperation 0.51; 0.46–0.57).

Interpretation — In our national register study of femoral neck fractures, THA had a lower risk than HA for further surgical procedures related to the hip. The reasons for lower mortality after THA are not known. Despite matching, there might be a selection of more healthy patients for this procedure, and other factors unknown to us, with or without relation to the choice of implant.     

Implant survival and radiographic outcome of total hip replacement in patients less than 20 years old

Background and purpose — Total hip replacement (THR) is not recommended for children and very young teenagers because early and repetitive revisions are likely. We investigated the clinical and radiographic outcomes of THR performed in children and teenage patients.

Patients and methods — We included 111 patients (132 hips) who underwent THR before 20 years of age. They were identified in the Norwegian Arthroplasty Register, together with information on the primary diagnosis, types of implants, and any revisions that required implant change. Radiographs and Harris hip score (HHS) were also evaluated.

Results — The mean age at primary THR was 17 (11–19) years and the mean follow-up time was 14 (3–26) years. The 10-year survival rate after primary THR (with the endpoint being any revision) was 70%. 39 patients had at least 1 revision and 16 patients had 2 or more revisions. In the latest radiographs, osteolysis and atrophy were observed in 19% and 27% of the acetabulae and 21% and 62% of the femurs, respectively. The mean HHS at the final follow-up was 83 (15–100).

Interpretation — The clinical score after THR in these young patients was acceptable, but many revisions had been performed. However, young patients with developmental dysplasia of the hip had lower implant survival. Moreover, the bone stock in these patients was poor, which could complicate future revisions.     

Consistency in patient-reported outcomes after total hip replacement

Purpose — The primary objective in this study was to describe the patient-reported outcome measures (PROMs) of total hip replacement (THR) patients 6 years after index surgery. Second, we sought to analyze how the preoperative, 1- and 6-year outcomes were associated.

Patients and methods — By assessing the Swedish Hip Arthroplasty Register (SHAR), 15,755 patients with complete follow-up were included in the study group. 1-year and 6-year response rates were 93% and 87%. PROMs used by the SHAR include the EQ-5D instrument, and 2 modified visual analogue scales, 1 for pain and 1 for satisfaction. We used a multivariable linear regression model to examine the relationship between preoperative, 1-year, and 6-year outcome.

Results — On average, patient-reported outcomes 6 years after THR were satisfactory. Though there was some deterioration in all mean 6-year PROMs, the patient-reported outcome after 6 years strongly resembled that of the 1-year results. The 1-year follow-up was the strongest factor associated with the 6-year results.

Interpretation — There is little deterioration in patient-reported outcomes 6 years after THR compared with the 1-year results. Although the 1-year follow-up was the strongest predictor of the 6-year results it could not alone explain the results, thus supporting the utility of the 6-year follow-up in THR patients.     

Do different types of bearings and noise from total hip arthroplasty influence hip-related pain,function, and quality of life postoperatively?

Background and purpose — Patient-reported outcome (PRO) is recognized as an important tool for evaluating the outcome and satisfaction after total hip arthroplasty (THA). We wanted to compare patient-reported outcome measure (PROM) scores from patients with ceramic-on-ceramic (CoC) THAs and those with metal-on-metal (MoM) THAs to scores from patients with metal-on-polyethylene (MoP) THAs, and to determine the influence of THA-related noise on PROM scores.

Patients and methods — We conducted a nationwide cross-sectional questionnaire survey in a cohort of patients identified from the Danish Hip Arthroplasty Registry. The PROMs included were: hip dysfunction and osteoarthritis and outcome score (HOOS), EQ-5D-3L, EQ VAS, UCLA activity score, and questions about noise from the THA. The response rate was 85% and the number of responders was 3,089. Of these, 45% had CoC THAs, 17% had MoM THAs, and 38% had MoP THAs, with a mean length of follow-up of 7, 5, and 7 years, respectively.

Results — Compared to MoP THAs, the mean PROM scores for CoC and MoM THAs were similar, except that CoC THAs had a lower mean score for HOOS Symptoms than did MoP THA. 27% of patients with CoC THAs, 29% with MoM THAs, and 12% with MoP THAs reported noise from their hip. For the 3 types of bearings, PROM scores from patients with a noisy THA were statistically significantly worse than those from patients with a silent MoP THA. The exception was noisy CoC and MoM THAs, which had the same mean UCLA activity score as silent MoP THAs.

Interpretation — A high proportion of patients reported noise from the THA, and these patients had worse PROM scores than patients with silent MoP THAs.     

Routine functional assessment for hip fracture patients

Background and purpose — Pre-fracture functional level has been shown to be a consistent predictor of rehabilitation outcomes in older hip fracture patients. We validated 4 overall pre-fracture functional level assessment instruments in patients aged 65 or more, used the prediction of outcome at 4 months post-fracture, and assessed cutoff values for decision making in treatment and rehabilitation.

Patients and methods — 165 consecutive patients with acute primary hip fracture were prospectively included in the study. Pre-fracture Barthel-20, Barthel-100, cumulated ambulation score, and new mobility score were scored immediately after admission. Outcome defined as mortality, residential status, and independent walking ability was assessed at 4 months.

Results — 3 of the assessment instruments, namely Barthel-20, Barthel-100, and new mobility score, correlated with outcome at 4 months post-fracture and were valid predictors. Thresholds were estimated. We found no evidence that Barthel-100, with its finer granularity, performs better than Barthel-20 as a predictor.

Interpretation — Our findings indicate that pre-fracture scores of Barthel-20 and new mobility score have predictive ability, and further investigation of usage for guidance of clinical and rehabilitation decisions concerning hip fracture patients is warranted.     

A retrospective study of acute kidney injury in hip arthroplasty patients receiving gentamicin and dicloxacillin

Background and purpose — Acute kidney injury is a known complication of antibiotic use. Antibiotic prophylaxis is essential to prevent periprosthetic infections after total hip replacement. We experienced a rise in the incidence of acute kidney injury (AKI), and in an effort to solve this problem, we changed our antibiotic prophylaxis protocol. We investigated whether removing gentamicin from our antibiotic protocol would cause fewer and less severe cases of renal impairment.

Patients and methods — We performed a retrospective study involving 136 cases of total hip replacement, with 66 patients receiving dicloxacillin and gentamicin and 70 patients receiving dicloxacillin alone.

Results — We found less cases of AKI in the dicloxacillin group (p = 0.03): the mean creatine level in the dicloxacillin/gentamicin group was 126 (25–422) μmol/L whereas it was 93 (39–278) μmol/L in the group that received dicloxacillin alone. We also found that cases were less severe in the dicloxacillin group than in the dicloxacillin/gentamicin group (p = 0.02). The relative risk of developing AKI was 3 times higher if dicloxacillin and gentamicin were both used (p = 0.02).

Interpretation — After removing gentamicin, there were fewer and less severe cases of acute kidney injury     

Recall and patient perceptions of hip precautions 6 weeks after total hip arthroplasty

Background and purpose — There is a lack of evidence to support the role of hip precautions in preventing dislocation following total hip arthroplasty (THA). We report an exploratory study which assesses recall, adherence, and the impact of precautions on activities of daily living in the first 6 weeks postoperatively.

Patients and methods — We designed a new questionnaire based on the education patients receive and refined by professionals within our multidisciplinary team. 129 patients underwent primary elective THA during the study period and received the questionnaire at 6 weeks postoperatively.

Results — 97 (75%) patients responded before the 8th week postoperatively. Most of these (83 patients) could remember all the precautions. Of the 97 who responded only 22 claimed to adhere to all of the precautions. 48 admitted to putting their own underwear on without the use of aids or assistance, and 38 had started walking without an aid. Due to the precautions 67 avoided leaving the house at some point and 63 were unable to perform desired activities. 84 stated that their sleep was affected. There were no dislocations among the 97 patients who responded; however, there was 1 dislocation among the 32 non-responders.

Interpretation — We found that most patients did not adhere to hip precaution advice. Precautions have a detrimental effect on patient activity and sleep. In view of the limited efficacy in reducing dislocation rate, we question the use of precautions in the primary arthroplasty setting.     

Incidence of scoliosis in cerebral palsy

Background and purpose — Surveillance of scoliosis in individuals with cerebral palsy (CP) is important for ensuring timely diagnosis and identification of curve progression. We analyzed the incidence of scoliosis in relation to age, sex, and gross motor function in a population-based cohort of individuals with CP.

Patients and methods — This was a prospective register study of all 1,025 individuals born 1990–2012 in southern Sweden (1.4 million inhabitants) in the Swedish surveillance program for CP, which included >95% of the total population of people with CP in the area. Annual clinical examinations and radiographic measurement of the Cobb angle of those with a moderate or severe scoliosis were registered. We determined the incidence of scoliosis related to age, sex, and the Gross Motor Function Classification System (GMFCS) level.

Results — The inclusion criteria were fulfilled by 962 individuals. The number of people (140/962) with scoliosis increased up to 20–25 years of age. The incidence of scoliosis was related to age and GMFCS level. In individuals at the lowest level of gross motor function (GMFCS V) scoliosis was seen in 10/131 before 5 years of age and at the age of 20 years 75% of these individuals had a Cobb angle ≥40°. No one in the highest level of motor function (GMFCS I) developed a Cobb angle ≥40°

Interpretation — Surveillance programs for scoliosis in CP should be based on age and GMFCS level and should be initiated at a young age and continued into adulthood.