A randomized controlled trial investigating the value of patient-specific instrumentation for total knee arthroplasty in the Canadian healthcare system.

AIMS: The purpose of the present study was to compare patient-specific instrumentation (PSI) and conventional surgical instrumentation (CSI) for total knee arthroplasty (TKA) in terms of early implant migration, alignment, surgical resources, patient outcomes, and costs. PATIENTS AND METHODS: The study was a prospective, randomized controlled trial of 50 patients undergoing TKA. There were 25 patients in each of the PSI and CSI groups. There were 12 male patients in the PSI group and seven male patients in the CSI group. The patients had a mean age of 69.0 years (sd 8.4) in the PSI group and 69.4 years (sd 8.4) in the CSI group. All patients received the same TKA implant. Intraoperative surgical resources and any surgical waste generated were recorded. Patients underwent radiostereometric analysis (RSA) studies to measure femoral and tibial component migration over two years. Outcome measures were recorded pre- and postoperatively. Overall costs were calculated for each group. RESULTS: There were no differences (p > 0.05) in any measurement of migration at two years for either the tibial or femoral components. Movement between one and two years was < 0.2 mm, indicating stable fixation. There were no differences in coronal or sagittal alignment between the two groups. The PSI group took a mean 6.1 minutes longer (p = 0.04) and used a mean 3.4 less trays (p < 0.0001). Total waste generated was similar (10 kg) between the two groups. The PSI group cost a mean CAD$1787 more per case (p < 0.01). CONCLUSION: RSA criteria suggest that both groups will have revision rates of approximately 3% at five years. The advantages of PSI were minimal or absent for surgical resources used and waste eliminated, and for meeting target alignment, yet had significantly greater costs. Therefore, we conclude that PSI may not offer any advantage over CSI for routine primary TKA cases. Cite this article: Bone Joint J 2019;101-B:565-572.

Highly crosslinked polyethylene wear rates and acetabular component orientation: a minimum ten-year follow-up.

Aims: The aim of this study was to determine whether there is a difference in the rate of wear between acetabular components positioned within and outside the 'safe zones' of anteversion and inclination angle. Patients and Methods: We reviewed 100 hips in 94 patients who had undergone primary total hip arthroplasty (THA) at least ten years previously. Patients all had the same type of acetabular component with a bearing couple which consisted of a 28 mm cobalt-chromium head on a highly crosslinked polyethylene (HXLPE) liner. A supine radiostereometric analysis (RSA) examination was carried out which acquired anteroposterior (AP) and lateral paired images. Acetabular component anteversion and inclination angles were measured as well as total femoral head penetration, which was divided by the length of implantation to determine the rate of polyethylene wear. Results: The mean anteversion angle was 19.4° (-15.2° to 48°, sd 11.4°), the mean inclination angle 43.4° (27.3° to 60.5°, sd 6.6°), and the mean wear rate 0.055 mm/year (sd 0.060). Exactly half of the hips were positioned inside the 'safe zone'. There was no difference (median difference, 0.012 mm/year; p = 0.091) in the rate of wear between acetabular components located within or outside the 'safe zone'. When compared to acetabular components located inside the 'safe zone', the wear rate was no different for acetabular components that only achieved the target anteversion angle (median difference, 0.012 mm/year; p = 0.138), target inclination angle (median difference, 0.013 mm/year; p = 0.354), or neither target (median difference, 0.012 mm/year; p = 0.322). Conclusion: Placing the acetabular component within or outside the 'safe zone' did not alter the wear rate of HXLPE at long-term follow-up to a level that risked osteolysis. HXLPE appears to be a forgiving bearing material in terms of articular surface wear, but care must still be taken to position the acetabular component correctly so that the implant is stable. Cite this article: Bone Joint J 2018;100-B:891-7.

Inducible displacement of cemented tibial components ten years after total knee arthroplasty.

AIMS: The aim of this study was to evaluate the long-term inducible displacement of cemented tibial components ten years after total knee arthroplasty (TKA). PATIENTS AND METHODS: A total of 15 patients from a previously reported prospective trial of fixation using radiostereometric analysis (RSA) were examined at a mean of 11 years (10 to 11) postoperatively. Longitudinal supine RSA examinations were acquired at one week, one year, and two years postoperatively and at final follow-up. Weight-bearing RSA examinations were also undertaken with the operated lower limb in neutral and in maximum internal rotation positions. Maximum total point motion (MTPM) was calculated for the longitudinal and inducible displacement examinations (supine versus standing, standing versus internal rotation, and supine versus standing with internal rotation). RESULTS: All patients showed some inducible displacement. Two patients with radiolucent lines had greater mean standing-supine MTPM displacement (1.35; sd 0.38) compared with the remaining patients (0.68; sd 0.36). These two patients also had a greater mean longitudinal MTPM at ten years (0.64; sd 0.50) compared with the remaining patients (0.39; sd 0.13 mm). CONCLUSION: Small inducible displacements in well-fixed cemented tibial components were seen ten years postoperatively, of a similar magnitude to that which has been reported for well-fixed components one to two years postoperatively. Greater displacements were found in components with radiolucent lines. Cite this article: Bone Joint J 2018;100-B:170-5.

Migration of a cemented fixed-bearing, polished titanium tibial baseplate (Genesis II) at ten years : a radiostereometric analysis.

AIMS: The purpose of the present study was to examine the long-term fixation of a cemented fixed-bearing polished titanium tibial baseplate (Genesis ll). PATIENTS AND METHODS: Patients enrolled in a previous two-year prospective trial (n = 35) were recalled at ten years. Available patients (n = 15) underwent radiostereometric analysis (RSA) imaging in a supine position using a conventional RSA protocol. Migration of the tibial component in all planes was compared between initial and ten-year follow-up. Outcome scores including the Knee Society Score, Western Ontario and McMaster Universities Arthritis Index, 12-item Short Form Health Survey, Forgotten Joint Score, and University of California, Los Angeles Activity Score were recorded. RESULTS: At ten years, the mean migration of the tibial component was less than 0.1 mm and 0.1° in all planes relative to the post-operative RSA exam. Maximum total point movement increased with time (p = 0.002) from 0.23 mm (sd 0.18) at six weeks to 0.42 mm (sd 0.20) at ten years. CONCLUSION: The low level of tibial baseplate migration found in the present study correlates to the low rate of revision for this implant as reported in individual studies and in joint replacement registries. TAKE HOME MESSAGE: Overall, the implant was found to be well fixed at ten years, supporting its continued clinical use and the predictive power of RSA for determining long-term fixation of implants. Cite this article: Bone Joint J 2016;98-B:616-21.

Highly cross-linked polyethylene decreases the rate of revision of total hip arthroplasty compared with conventional polyethylene at 13 years' follow-up.

AIMS: The purpose of this study was to compare the long-term results of primary total hip arthroplasty (THA) in young patients using either a conventional (CPE) or a highly cross-linked (HXLPE) polyethylene liner in terms of functional outcome, incidence of osteolysis, radiological wear and rate of revision. METHODS: We included all patients between the ages of 45 and 65 years who, between January 2000 and December 2001, had undergone a primary THA for osteoarthritis at our hospital using a CPE or HXLPE acetabular liner and a 28 mm cobalt-chrome femoral head. From a total of 160 patients, 158 (177 hips) were available for review (CPE 89; XLPE 88). The mean age, body mass index (BMI) and follow-up in each group were: CPE: 56.8 years (46 to 65); 30.7 kg/m(2) (19 to 58); 13.2 years (2.1 to 14.7) and HXLPE: 55.6 years (45 to 65); BMI: 30 kg/m(2) (18 to 51); 13.1 years (5.7 to 14.4). RESULTS: The mean Harris hip score (HHS) at final follow-up was 89.3 for the CPE group and 90.9 for the HXLPE group (p = 0.078). Osteolysis was present around 15 acetabular (17%) and 16 femoral (18%) components in the CPE hips compared with none (0%) in the HXLPE hips. The mean radiological linear wear of the CPE liners was 0.11 mm/year compared with 0.035 mm/year for the HXLPE liners (p = 0.006). The cumulative implant survival, with revision for polyethylene wear as the endpoint, was 86% (95% confidence interval 78 to 94) in the CPE group and 100% in the HXLPE group at 13 years (numbers at risk at 13 years - CPE: 65, XLPE: 61). DISCUSSION: This study shows that HXLPE liners are associated with significantly less osteolysis and a lower rate of revision THA than CPE liners at long-term follow-up. TAKE HOME MESSAGE: The findings of this study highlight the clinical benefits of using HXLPE liners in THA and support the routine use of the material in order to improve implant longevity and to decrease the number of patients needing revision for aseptic osteolysis.

Hip arthroscopy in the setting of hip arthroplasty.

PURPOSE: Hip arthroscopy has traditionally been viewed as a hip preservation procedure performed in patients with native joint pathology. However, as the list of indications for arthroscopic hip intervention grows, further advances are expanding its use. The purpose of this systematic review was to examine existing evidence supporting the use of hip arthroscopy in the setting of hip arthroplasty. METHODS: Using predetermined inclusion criteria, EMBASE, MEDLINE and PubMed were searched for articles addressing arthroscopic hip surgery performed in hips containing joint replacement arthroplasties. Inclusion criteria limited our search to human and English language studies addressing articles where clear surgical indications are described. Article screening was conducted in duplicate. RESULTS: Seven-hundred and forty-three studies were retrieved before duplicate screening, and 18 satisfied inclusion criteria. Eleven case series, six case reports and one prospective cohort study are included. In total, 171 patients underwent hip arthroscopy following previous arthroplasty. Indications for arthroscopy included iliopsoas tendinopathy (35.8%), symptomatic hips with no clear diagnosis despite extensive investigation (24.6%), periprosthetic infection (6.4%) and intra-articular loose bodies (3.5%). Almost all patients who underwent hip arthroscopy experienced positive outcomes from the procedure. CONCLUSION: Hip arthroscopy after hip arthroplasty is supported by our systematic review for a variety of indications. Hip arthroscopy can be a safe and effective method of treating hip arthroplasty patients with iliopsoas tendinopathy. Hip arthroscopy also has utility in patients with symptomatic hip arthroplasty despite exhaustion of other diagnostic avenues. LEVEL OF EVIDENCE: A systematic review of level IV studies.

Knee manipulation under anaesthetic following total knee arthroplasty: a matched cohort design.

The purpose of this study was to compare clinical outcomes of total knee arthroplasty (TKA) after manipulation under anaesthesia (MUA) for post-operative stiffness with a matched cohort of TKA patients who did not requre MUA. In total 72 patients (mean age 59.8 years, 42 to 83) who underwent MUA following TKA were identified from our prospective database and compared with a matched cohort of patients who had undergone TKA without subsequent MUA. Patients were evaluated for range of movement (ROM) and clinical outcome scores (Western Ontario and McMaster Universities Arthritis Index, Short-Form Health Survey, and Knee Society Clinical Rating System) at a mean follow-up of 36.4 months (12 to 120). MUA took place at a mean of nine weeks (5 to 18) after TKA. In patients who required MUA, mean flexion deformity improved from 10° (0° to 25°) to 4.4° (0° to 15°) (p < 0.001), and mean range of flexion improved from 79.8° (65° to 95°) to 116° (80° to 130°) (p < 0.001). There were no statistically significant differences in ROM or functional outcome scores at three months, one year, or two years between those who required MUA and those who did not. There were no complications associated with manipulation. At most recent follow-up, patients requiring MUA achieved equivalent ROM and clinical outcome scores when compared with a matched control group. While other studies have focused on ROM after manipulation, the current study adds to current literature by supplementing this with functional outcome scores.

A randomised trial comparing a short and a standard-length metaphyseal engaging cementless femoral stem using radiostereometric analysis.

This was a randomised controlled trial studying the safety of a new short metaphyseal fixation (SMF) stem. We hypothesised that it would have similar early clinical results and micromovement to those of a standard-length tapered Synergy metaphyseal fixation stem. Using radiostereometric analysis (RSA) we compared the two stems in 43 patients. A short metaphyseal fixation stem was used in 22 patients and a Synergy stem in 21 patients. No difference was found in the clinical outcomes pre- or post-operatively between groups. RSA showed no significant differences two years post-operatively in mean micromovement between the two stems (except for varus/valgus tilt at p = 0.05) (subsidence 0.94 mm (SD 1.71) vs 0.32 mm (SD 0.45), p = 0.66; rotation 0.96° (SD 1.49) vs 1.41° (SD 2.95), p = 0.88; and total migration 1.09 mm (SD 1.74) vs 0.73 mm (SD 0.72), p = 0.51). A few stems (four SMF and three Synergy) had initial migration > 1.0 mm but stabilised by three to six months, with the exception of one SMF stem which required revision three years post-operatively. For most stems, total micromovement was very low at two years (subsidence < 0.5 mm, rotation < 1.0°, total migration < 0.5 mm), which was consistent with osseous ingrowth. The small sample makes it difficult to confirm the universal applicability of or elucidate the potential contraindications to the use of this particular new design of stem.

Metal ion levels after metal-on-metal total hip arthroplasty: a five-year, prospective randomized trial.

BACKGROUND: The U.S. Food and Drug Administration has requested post-market surveillance data, including data on metal ion levels, regarding metal-on-metal total hip arthroplasty. We performed a prospective, randomized study of metal ion levels in erythrocytes, serum, and whole blood at five years after 28 and 36-mm metal-on-metal and 28-mm metal-on-polyethylene total hip arthroplasty. METHODS: One hundred and five enrolled patients were randomized equally to the three bearing surface options and were blinded with regard to their treatment group. Metal ion measurements and clinical evaluations were performed at regular intervals. RESULTS: Cobalt and chromium ion levels in all blood sample types at the five-year time point were significantly lower in the metal-on-polyethylene group than in each of the two metal-on-metal groups (p < 0.001) with the exception of chromium in erythrocytes (p = 0.194). Cobalt in serum (p = 0.029) and erythrocytes (p = 0.002) showed significant increases from two to five years in the 36-mm metal-on-metal group; similar increases were not seen in the 28-mm metal-on-metal group. At five years, five patients in the 36-mm metal-on-metal group and none in the 28-mm metal-on-metal group had cobalt or chromium levels of >7 ppb. Correlations among levels in serum, erythrocyte, and whole blood were stronger for cobalt than for chromium. One patient in the 36-mm metal-on-metal group underwent revision because of an adverse local tissue reaction. CONCLUSIONS: The 36-mm metal-on-metal bearing underperformed the 28-mm metal-on-metal bearing with respect to metal ion levels. The authors are closely following all patients treated with metal-on-metal total hip arthroplasty.

Results of the PeRception of femOroaCetabular impingEment by Surgeons Survey (PROCESS).

PURPOSE: Currently, there is a lack of high-level evidence addressing the variety of treatment options available for patients diagnosed with femoroacetabular impingement (FAI). The objective was to determine the current state of practice for FAI in Canada. METHODS: A questionnaire was developed and pretested to address the current state of knowledge among orthopaedic surgeons regarding FAI treatment using a focus group of experts, reviewing prior surveys, and reviewing online guidelines addressing surgical interventions for FAI. The membership of the Canadian Orthopaedic Association (COA) was surveyed through email and mail in both French and English. RESULTS: Two hundred and two surveys were obtained (20 % response rate), of which 74.3 % of respondents manage patients under age 40 with hip pain. Most surgeons (62 %) considered failure of non-operative management as the most important indication for the surgical management of FAI, usually by treating both bony and soft tissue damage (54.4 %). The majority of surgeons were unsure of the existence of evidence supporting the best clinical test for FAI, the use of a diagnostic intra-articular injection for diagnosis of FAI, and for non-operative management of FAI. One in four respondents supported a sham surgery (24.8 %) control arm for a trial evaluating the impact of surgical intervention on FAI. CONCLUSIONS: This survey elucidates areas of research for future studies relevant to FAI and highlights controversial areas of treatment. The results suggest that the current management of FAI by members of the COA is limited by a lack of awareness of high-level evidence.

Does morbid obesity affect the outcome of total hip replacement?: an analysis of 3290 THRs.

We evaluated the outcome of primary total hip replacement (THR) in 3290 patients with the primary diagnosis of osteoarthritis at a minimum follow-up of two years. They were stratified into categories of body mass index (BMI) based on the World Health Organisation classification of obesity. Statistical analysis was carried out to determine if there was a difference in the post-operative Western Ontario and McMaster Universities osteoarthritis index, the Harris hip score and the Short-Form-12 outcome based on the BMI. While the pre- and post-operative scores were lower for the group classified as morbidly obese, the overall change in outcome scores suggested an equal if not greater improvement compared with the non-morbidly obese patients. The overall survivorship and rate of complications were similar in the BMI groups although there was a slightly higher rate of revision for sepsis in the morbidly obese group. Morbid obesity does not affect the post-operative outcome after THR, with the possible exception of a marginally increased rate of infection. Therefore withholding surgery based on the BMI is not justified.

Randomised controlled trial comparing early migration of two collarless polished cemented stems using radiostereometric analysis.

This was a safety study where the hypothesis was that the newer-design CPCS femoral stem would demonstrate similar early clinical results and micromovement to the well-established Exeter stem. Both are collarless, tapered, polished cemented stems, the only difference being a slight lateral to medial taper with the CPCS stem. A total of 34 patients were enrolled in a single-blinded randomised controlled trial in which 17 patients received a dedicated radiostereometric CPCS stem and 17 a radiostereometric Exeter stem. No difference was found in any of the outcome measures pre-operatively or post-operatively between groups. At two years, the mean subsidence for the CPCS stem was nearly half that seen for the Exeter stem (0.77 mm (-0.943 to 1.77) and 1.25 mm (0.719 to 1.625), respectively; p = 0.032). In contrast, the mean internal rotation of the CPCS stem was approximately twice that of the Exeter (1.61 degrees (-1.07 degrees to 4.33 degrees ) and 0.59 degrees (0.97 degrees to 1.64 degrees ), respectively; p = 0.048). Other migration patterns were not significantly different between the stems. The subtle differences in designs may explain the different patterns of migration. Comparable migration with the Exeter stem suggests that the CPCS design will perform well in the long term.

The Install Award. Survivorship of the high tibial valgus osteotomy. A 10- to -22-year followup study.

The results of 106 high tibial valgus osteotomies in 85 patients were evaluated after a minimum 10-year followup to determine survivorship, complications, and risk factors associated with failure. Using Kaplan-Meier survivorship analysis, 73% of patients at 5 years, 51% of patients at 10 years, 39% at 15 years, and 30% at 20 years after high tibial osteotomy had not required conversion of the high tibial osteotomy to a total knee arthroplasty. Univariate Cox regression analysis of risk factors showed that age older than 50 years, previous arthroscopic debridement, presence of a lateral tibial thrust, preoperative knee flexion less than 120 degrees, insufficient valgus correction, and development of delayed union or nonunion were significantly associated with probability of early failure. Multivariate Cox regression analysis showed that a body mass index of less than 25 kg/m2, presence of a lateral tibial thrust, and development of delayed union or nonunion were significantly associated with probability of early failure. Using recursive partitioning analysis of risk factors with the Wilcoxon test, a subset of patients who were younger than 50 years of age and who had preoperative knee flexion greater than 120 degrees had a probability of survival after high tibial osteotomy approaching 95% at 5 years, 80% at 10 years, and 60% at 15 years. These results suggest that survival of high tibial osteotomy can be improved through careful patient selection and surgical technique.

Complications of limb-lengthening in children who have an underlying bone disorder.

We retrospectively reviewed the results, particularly with regard to complications, of lengthening of long bones in eight children (nine limb segments) who had a limb-length discrepancy secondary to an underlying bone disorder (Group 1). The mean age of these patients was twelve years (range, six to sixteen years), the mean preoperative limb-length discrepancy was 6.0 centimeters (range, 2.7 to 8.8 centimeters), and the mean lengthening of the nine limb segments was 6.2 centimeters (range, 2.7 to 9.0 centimeters). Only two extremities were equalized. We compared the results in Group 1 with those of limb-lengthening in seven children (nine limb segments) who had a discrepancy secondary to post-traumatic growth arrest (Group 2) and seven children (seven limb segments) who had a discrepancy secondary to growth arrest following an infection in the bone (Group 3). All of the procedures were performed at our institution during the same time-period by the same surgeons. There were forty-one complications (twenty-five minor and sixteen major), with a mean of five complications per limb segment, in Group 1; twenty-six complications (twenty minor and six major), with a mean of three complications per limb segment, in Group 2; and twenty-two complications (fourteen minor and eight major), with a mean of three complications per limb segment, in Group 3. The results in Group 1 suggest that the Ilizarov technique for lengthening, although effective in restoring the length of the extremity, is associated with a higher rate of complications in patients who have a discrepancy due to an underlying bone disorder than in those who have a discrepancy due to growth arrest. Therefore, caution should be exercised before a lengthening procedure is recommended for a patient who has an underlying bone disorder.

Management of fibular hemimelia: amputation or limb lengthening.

We reviewed retrospectively 22 patients (23 limb segments) with fibular hemimelia treated by amputation or limb lengthening to evaluate these methods of treatment. There were 12 boys and 10 girls, all with associated anomalies in the lower limbs. Twelve patients (13 limb segments) had early amputation and prosthetic fitting and ten had tibial lengthening using the Ilizarov technique. At the latest follow-up, the twelve patients who had amputation were functioning well and had few complications. The ten patients who had lengthening had suffered numerous complications, and all had needed either further corrective surgery or to wear braces or shoe-raises. Two of the ten lengthened limbs required late amputation for poor function or cosmesis. There were fewer hospital admissions, clinic visits, and periods of absence from school in the amputation group. Our findings suggest that amputation is a more effective method of management than limb-lengthening in severe fibular hemimelia. The Ilizarov method is an attractive alternative for selected patients, but its exact role is not yet established. One problem is that families often have unrealistic expectations of the surgical and prosthetic technology available and may refuse amputation when this has been recommended.

Open fractures of the tibia in children.

Ninety open fractures of the tibia treated at the authors' institution between 1985 and 1994 were retrospectively reviewed. There were 38 Grade I, 35 Grade II, and 17 Grade III fractures. All patients had debridement and lavage of the wound under general anesthesia. Seventeen wounds (19.8%) were closed primarily and 69 (80.2%) were left open. Forty fractures (45.0%) were stabilized in casts, 31 (34.8%) in an external fixator, and 18 (20.2%) with casts and internal fixation. Six patients (7.1%) had superficial infection occur, 2 had vascular injuries, 1 of whom required an amputation, and only 1 had a neurologic injury. The average time to union was 4.5 months (range, 1.2-28.3 months). there were 10 delayed and 7 nonunions. Multiple regression analysis showed that only age of the patient and grade of the fracture were significantly associated with union time. Open fractures of the tibia in children older than 12 years of age have a high risk of developing delayed or nonunion when compared with the same injuries in children younger than 6 years of age.