Objective

Carpal tunnel release surgery is a commonly performed procedure for alleviating symptoms of median nerve compression and restoring hand function. With pressure on theatre time these procedures are now commonly performed in a step-down out-patient facility under local anaesthetic. The choice of suture for skin closure in this procedure can impact the quality of wound healing, patient outcomes and the follow-up required however the question of the best type of suture remains unanswered. The purpose of this study was to compare the outcomes of absorbable and non-absorbable sutures using a randomised control trial design.

Abstract

Abstract

Fractures of the humeral diaphysis occur in a bimodal distribution and represent 3-5% of all fractures. Presently, the standard treatment of isolated humeral diaphyseal fractures is nonoperative care using splints, braces, and slings. Recent data has questioned the effectiveness of this strategy in ensuring fracture healing and optimal patient function. The primary objective of this randomized controlled trial (RCT) was to assess whether operative treatment of humeral shaft fractures with a plate and screw construct provides a better functional outcome than nonoperative treatment. Secondary objectives compared union rates and both clinical and patient-reported outcomes.

Eligible patients with an isolated, closed humeral diaphyseal fracture were randomized to either nonoperative care (initial sugar-tong splint, followed by functional coaptation brace) or open reduction and internal fixation (ORIF; plate and screw construct). The primary outcome measure was the Disability Shoulder, Arm, Hand (DASH) score assessed at 2-, 6-, 16-, 24-, and 52-weeks. Secondary outcomes included the Short Musculoskeletal Functional Assessment (SMFA), the Constant Shoulder Score, range of motion (ROM), and radiographic parameters. Independent samples t-tests and Chi-squared analyses were used to compare treatment groups. The DASH, SMFA, and Constant Score were modelled over time using a multiple variable mixed effects model.

A total of 180 patients were randomized, with 168 included in the final analysis. There were 84 patients treated nonoperatively and 84 treated with ORIF. There was no significant difference between the two treatment groups for age (mean = 45.4 years, SD 16.5 for nonoperative group and 41.7, SD 17.2 years for ORIF group; p=0.16), sex (38.1% female in nonoperative group and 39.3% female in ORIF group; p=0.87), body mass index (mean = 27.8, SD 8.7 for nonoperative group and 27.2, SD 6.2 for ORIF group; p=0.64), or smoking status (p=0.74). There was a significant improvement in the DASH scores at 6 weeks in the ORIF group compared to the nonoperative group (mean=33.8, SD 21.2 in the ORIF group vs. mean=56.5, SD=21.1 in the nonoperative group; p < 0 .0001). At 4 months, the DASH scores were also significantly better in the ORIF group (mean=21.6, SD=19.7 in the ORIF group vs. mean=31.6, SD=24.6 in the nonoperative group; p=0.009. However, there was no difference in DASH scores at 12-month follow-up between the groups (mean=8.8,SD=10.9 vs. mean=11.0, SD=16.9 in the nonoperative group; p=0.39). Males had improved DASH scores at all timepoints compared with females. There was significantly quicker time to union (p=0.016) and improved position (p < 0 .001) in the ORIF group. There were 13 (15.5%) nonunions in the nonoperative group and four (4.7%) combined superficial and deep infections in the ORIF group. There were seven radial nerve palsies in the nonoperative group and five (a single iatrogenic) radial nerve palsies in the ORIF group.

This large RCT comparing operative and nonoperative treatment of humeral diaphyseal fractures found significantly improved functional outcome scores in patients treated surgically at 6 weeks and 4 months. However, the early functional improvement did not persist at the 12-month follow-up. There was a 15.5% nonunion rate, which required surgical intervention, in the nonoperative group and a similar radial nerve palsy rate between groups.

Our primary objective was to compare healing rates in patients undergoing arthroscopic rotator cuff repair for degenerative tears, with and without bone channeling. Our secondary objectives were to compare disease-specific quality of life and patient reported outcomes as measured by the Western Ontario Rotator Cuff Index (WORC), American Shoulder and Elbow Surgeons (ASES) score and Constant score between groups.

Patients undergoing arthroscopic rotator cuff repair at three sites were randomized to receive either bone channeling augmentation or standard repair. Healing rates were determined by ultrasound at 6 and 24 months post operatively. WORC, ASES, and Constant scores were compared between groups at baseline and at 3, 6, 12 and 24 months post operatively.

One hundred sixty-eight patients were recruited and randomized between 2013 to 2018. Statistically significant improvements occurred in both groups from pre-operative to all time points in all clinical outcome scores (p < 0 .0001). Intention to treat analysis revealed no statistical differences in healing rates between the two interventions at 24 months post-operative. No differences were observed in WORC, ASES or Constant scores at any time-point.

This trial did not demonstrate superiority of intra-operative bone channeling in rotator cuff repair surgery at 24 months post-operative. Healing rates and patient-reported function and quality of life measures were similar between groups.

Fractures of the humeral diaphysis occur in a bimodal distribution and represent 3-5% of all fractures. Presently, the standard treatment of isolated humeral diaphyseal fractures is nonoperative care using splints, braces, and slings. Recent data has questioned the effectiveness of this strategy in ensuring fracture healing and optimal patient function. The primary objective of this randomized controlled trial (RCT) was to assess whether operative treatment of humeral shaft fractures with a plate and screw construct provides a better functional outcome than nonoperative treatment. Secondary objectives compared union rates and both clinical and patient-reported outcomes.

Eligible patients with an isolated, closed humeral diaphyseal fracture were randomized to either nonoperative care (initial sugar-tong splint, followed by functional coaptation brace) or open reduction and internal fixation (ORIF; plate and screw construct). The primary outcome measure was the Disability Shoulder, Arm, Hand (DASH) score assessed at 2-, 6-, 16-, 24-, and 52-weeks. Secondary outcomes included the Short Musculoskeletal Functional Assessment (SMFA), the Constant Shoulder Score, range of motion (ROM), and radiographic parameters. Independent samples t-tests and Chi-squared analyses were used to compare treatment groups. The DASH, SMFA, and Constant Score were modelled over time using a multiple variable mixed effects model.

A total of 180 patients were randomized, with 168 included in the final analysis. There were 84 patients treated nonoperatively and 84 treated with ORIF. There was no significant difference between the two treatment groups for age (mean = 45.4 years, SD 16.5 for nonoperative group and 41.7, SD 17.2 years for ORIF group; p=0.16), sex (38.1% female in nonoperative group and 39.3% female in ORIF group; p=0.87), body mass index (mean = 27.8, SD 8.7 for nonoperative group and 27.2, SD 6.2 for ORIF group; p=0.64), or smoking status (p=0.74). There was a significant improvement in the DASH scores at 6 weeks in the ORIF group compared to the nonoperative group (mean=33.8, SD 21.2 in the ORIF group vs. mean=56.5, SD=21.1 in the nonoperative group; p < 0 .0001). At 4 months, the DASH scores were also significantly better in the ORIF group (mean=21.6, SD=19.7 in the ORIF group vs. mean=31.6, SD=24.6 in the nonoperative group; p=0.009. However, there was no difference in DASH scores at 12-month follow-up between the groups (mean=8.8,SD=10.9 vs. mean=11.0, SD=16.9 in the nonoperative group; p=0.39). Males had improved DASH scores at all timepoints compared with females. There was significantly quicker time to union (p=0.016) and improved position (p < 0 .001) in the ORIF group. There were 13 (15.5%) nonunions in the nonoperative group and four (4.7%) combined superficial and deep infections in the ORIF group. There were seven radial nerve palsies in the nonoperative group and five (a single iatrogenic) radial nerve palsies in the ORIF group.

This large RCT comparing operative and nonoperative treatment of humeral diaphyseal fractures found significantly improved functional outcome scores in patients treated surgically at 6 weeks and 4 months. However, the early functional improvement did not persist at the 12-month follow-up. There was a 15.5% nonunion rate, which required surgical intervention, in the nonoperative group and a similar radial nerve palsy rate between groups.

The aim of this study was to investigate surgeons’ reported change of treatment preference in response to the results and conclusion from a randomized controlled trial (RCT) and to study patterns of change between subspecialties and nationalities.

Two questionnaires were developed through the Delphi process for this cross-sectional survey of surgical preference. The first questionnaire was sent out before the publication of a RCT and the second questionnaire was sent out after publication. The RCT investigated repair or non-repair of the pronator quadratus (PQ) muscle during volar locked plating of distal radial fractures (DRFs). Overall, 380 orthopaedic surgeons were invited to participate in the first questionnaire, of whom 115 replied. One hundred surgeons were invited to participate in the second questionnaire. The primary outcome was the proportion of surgeons for whom a treatment change was warranted, who then reported a change of treatment preference following the RCT. Secondary outcomes included the reasons for repair or non-repair, reasons for and against following the RCT results, and difference of preferred treatment of the PQ muscle between surgeons of different nationalities, qualifications, years of training, and number of procedures performed per year.

Of the 100 surgeons invited for the second questionnaire, 74 replied. For the primary outcome, 6 of 32 surgeons (19%), who usually repaired the PQ muscle and therefore a change of treatment preference was warranted, reported a change of treatment preference based on the RCT publication. Of the secondary outcomes, restoring anatomy was the most common response for repairing the PQ muscle.

The majority of the orthopaedic surgeons, where a change of treatment preference was warranted based on the results and conclusion of a RCT, did not report willingness to change their treatment preference.

Plantar fasciitis (PF) is one of the widespread conditions causing hindfoot pain. The most common presenting symptoms are functional limitation and pain (first step and activity) on plantar surface of the foot. The non-operative treatments provide complete resolution of pain in 90% of patients, but functional limitation still remains as a risk factor for recurrency of PF. Although the number of non-operative treatment options showing efficacy on pain and functional limitation are excessive, the evidences are limited for functional limitation. Additionally, Mulligan mobilization with movement (MMWM) in Chronic Plantar Fasciitis has been poorly studied in the literature. According to these findings, the study was aimed to determine effectiveness of Mulligan mobilization with movement on Chronic Plantar Fasciitis.

A total of 25 patients (40 feet) with chronic PF were included in the study. The patients were randomly divided into Mulligan concept rehabilitation group (PF-M, n=20 feet) and Home Rehabilitation group (PF-H, n=20 feet). (MMWM), Foot and ankle exercises program were applied to PF-M, twice a week totally 8 week (16 sessions) and foot- ankle exercises as a home program were given for PF-H, 8 weeks. The range of motion (ROM) for dorsiflexion and plantar flexion was measured by using a manual goniometer. Pain, disability and activity restriction were assessed by Foot Function Index (FFI) . The first step morning pain was evaluated by Visual Analogue Scale (VAS) and Kinesiophobia was also reported by using Tampa Scale (TSK). Patients were evaluated at baseline and 8 weeks.

FFI, VAS, TSK, ROM values improved in all groups (intragroup variability) at 8th week (P < .05). The other result indicated that ROM values for DF and PF and TSK scores in PF-M had more significant improvement than PF-H (p<.05).

To the best of our knowledge this is the first randomised controlled trial for investigating Mulligan Concept efficiancy on chronic PF. Both Mulligan mobilization with movement (MMWM) and exercise protocols are effective for chronic PF. Furthermore, The Mulligan concept seems more effective treatment option in reducing kinesiophobia and improving functional capacity.

This study used model-based radiostereometric analysis (MBRSA) to compare migration of a recently introduced cementless hip stem to an established hip stem of similar design. Novel design features of the newer hip stem included a greater thickness of hydroxyapatite coating and a blended compaction extraction femoral broach.

Fifty-seven patients requiring primary total hip arthroplasty (THA) were enrolled at a single centre. Patients were randomized to receive either an Avenir collarless stem and Trilogy IT cup (ZimmerBiomet) or a Corail collarless stem and Pinnacle cup (DePuy Synthes) via a posterior or lateral approach. Both stems are broach-only femoral bone preparation. RSA beads (Halifax Biomedical) were inserted into the proximal femur during surgery. Patients underwent supine RSA imaging a 6 weeks (baseline), 6, 12, and 24 months following surgery. The primary study outcome was total subsidence of the hip stem from baseline to 24 months as well as progression of subsidence between 12 and 24 months. These values were compared against published migration thresholds for well-performing hip stems (0.5mm). The detection limit, or precision, of MBRSA was calculated based on duplicate examinations taken at baseline. Patient reported outcome measures were collected throughout the study and included the Oxford-12 Hip Score (OHS), EuroQoL EQ-5D-5L, Hip Osteoarthritis Score (HOOS) as well as visual analogue scales (VAS) for thigh pain and satisfaction. Analysis comprised of paired and unpaired t-tests with significance set at p≤0.05.

Forty-eight patients (30 males) were included for analysis; 7 patients received a non-study hip stem intra-operatively, 1 patient suffered a traumatic dislocation within three weeks of surgery, and 1 patient died within 12 months post-surgery. RSA data was obtained for 45 patients as three patients did not receive RSA beads intra-operatively. Our patient cohort had a mean age of 65.9 years (±;7.2) at the time of surgery and body mass index of 30.5 kg/m2 (±;5.2). No statistical difference in total stem migration was found between the Avenir and Corail stems at 12 months (p=0.045, 95%CI: −0.046 to 0.088) and 24 months (p=0.936, 95% CI: −0.098 to 0.090). Progression of subsidence from 12-24 months was 0.011mm and 0.034mm for the Avenir and Corail groups which were not statistically different (p=0.163, 95%CI: −0.100 to 0.008) between groups and significantly less than the 0.5mm threshold (pNo statistically significant differences existed between study groups for any pre-operative function scores (p>0.05). All patients showed significant functional improvement from pre- to post-surgery and no outcome measures were different between study groups with exception of EQ-5D-5L health visual analogue scale at 12 months which showed marginally superior (p=0.036) scores in the Avenir group. This study was not powered to detect differences in clinical outcomes.

This study has demonstrated no statistical difference in subsidence or patient-reported outcomes between the Corail hip stem and the more recently introduced Avenir hip stem. This result is predictable as both stems are of a triple-tapered design, are coated with hydroxyapatite, and utilize a broach-only bone preparation technique. Both stem designs demonstrate migration below 0.5mm suggesting both are low-risk for aseptic loosening in the long-term.

The direct superior approach (DSA) is a modification of the posterior approach (PA) that preserves the iliotibial band and short external rotators except for the piriformis or conjoined tendon during total hip arthroplasty (THA). The objective of this study was to compare postoperative pain, early functional rehabilitation, functional outcomes, implant positioning, implant migration, and complications in patients undergoing the DSA versus PA for THA.

This study included 80 patients with symptomatic hip arthritis undergoing primary THA. Patients were prospectively randomised to receive either the DSA or PA for THA, surgery was undertaken using identical implant designs in both groups, and all patients received a standardized postoperative rehabilitation programme. Predefined study outcomes were recorded by blinded observers at regular intervals for two-years after THA. Radiosteriometric analysis (RSA) was used to assess implant migration.

There were no statistical differences between the DSA and PA in postoperative pain scores (p=0.312), opiate analgesia consumption (p=0.067), and time to hospital discharge (p=0.416). At two years follow-up, both groups had comparable Oxford hip scores (p=0.476); Harris hip scores (p=0.293); Hip disability and osteoarthritis outcome scores (p=0.543); University of California at Los Angeles scores (p=0.609); Western Ontario and McMaster Universities Arthritis Index (p=0.833); and European Quality of Life questionnaire with 5 dimensions scores (p=0.418). Radiographic analysis revealed no difference between the two treatment groups for overall accuracy of acetabular cup positioning (p=0.687) and femoral stem alignment (p=0.564). RSA revealed no difference in femoral component migration (p=0.145) between the groups at two years follow-up.

There were no differences between patients undergoing the DSA versus PA for THA with respect to postoperative pain scores, functional rehabilitation, patient-reported outcome measurements, accuracy of implant positioning, and implant migration at two years follow-up. Both treatment groups had excellent outcomes that remained comparable at all follow-up intervals.

Introduction

Exercise is recommended as first-line treatment for patients with hip osteoarthritis (OA). Interestingly, content and dose of exercise interventions seem to be important for the effect of exercise interventions, but the optimal content and dose is unknown. This warrants randomized controlled trials providing evidence for the optimal exercise program in Hip OA. The aim of this trial was to investigate whether progressive resistance training (PRT) is superior to neuromuscular exercise (NEMEX) for improving functional performance, hip pain and hip-related quality of life in patients with hip OA.

Studies have shown that 10–30% patients do not achieve optimal function outcomes after total hip replacement (THR). High quality randomised controlled trials (RCTs) evaluating the clinical and cost-effectiveness of techniques to improve functional outcomes after THR are lacking. We performed this study to evaluate the feasibility of a RCT comparing patient-reported functional outcomes after hybrid or fully cemented THR (ISRCTN11097021).

Patients were recruited from two centres and randomised to receive either a fully cemented or hybrid THR. Data collection included Patient Reported Outcome Measures (PROMs), non-serious adverse events of special interest (AESI), serious adverse device effects (SADE) and NHS resource use. Qualitative interviews were undertaken to understand a) patient experiences of study processes and their reasons for taking part or not, and b) to understand surgeons’ perceptions of the study, factors affecting willingness to participate, and barriers to implementation of the future RCT findings.

The target of 40 patients were successfully recruited for the feasibility RCT; the ratio of successful recruitment to eligible patients was 0.61 across both sites. Treatment crossovers occurred in four patients, all related to bone quality. Four patients were withdrawn due to not undergoing surgery within the study window because of the pandemic. Follow-up was 100% and PROMs were completed by all patients at all time points. The feasibility of conducting a within-trial cost-utility analysis was demonstrated. Interviews were conducted with 27 patients and 16 surgeons. Patients and surgeons generally found the study procedures acceptable and workable. Some declined participation because they did not want treatment allocated at random, or because blinding was off-putting. Surgeons’ perceptions of equipoise varied, and implementation of findings from the future RCT would need to recognise the ‘craft’ nature of surgery and the issue of training.

We conclude that a full RCT with economic analysis will be both feasible and practicable, although mechanisms to safely implement potential changes to practice because of RCT findings may need consideration by the wider arthroplasty community.

Aim

In 10% of the presumed aseptic hip or knee revisions, a low-grade infection is unexpectedly diagnosed based on the tissue samples taken during revision. Extended antimicrobial prophylaxis can possibly reduce the failure rate in cases of unexpected PJI, because the prophylaxis can be considered as early empiric treatment. In this randomized controlled study we analysed whether extended antimicrobial prophylaxis compared to a single dose is beneficial to improve the outcome of treatment in unexpected PJI in revision arthroplasty.

Abstract

Orthopaedic surgeons prescribe more opioids than any other surgical speciality. Opioids remain the analgesic of choice following arthroscopic knee and shoulder surgery. There is growing evidence that opioid-sparing protocols may reduce postoperative opioid consumption while adequately addressing patients’ pain. However, there are a lack of prospective, comparative trials evaluating their effectiveness. The objective of the current randomized controlled trial (RCT) was to evaluate the efficacy of a multi-modal, opioid-sparing approach to postoperative pain management in patients undergoing arthroscopic shoulder and knee surgery.

The NO PAin trial is a pragmatic, definitive RCT (NCT04566250) enrolling 200 adult patients undergoing outpatient shoulder or knee arthroscopy. Patients are randomly assigned in a 1:1 ratio to an opioid-sparing group or standard of care. The opioid-sparing group receives a three-pronged prescription package consisting of 1) a non-opioid prescription: naproxen, acetaminophen and pantoprazole, 2) a limited opioid “rescue prescription” of hydromorphone, and 3) a patient education infographic. The control group is the current standard of care as per the treating surgeon, which consists of an opioid analgesic. The primary outcome of interest is oral morphine equivalent (OME) consumption up to 6 weeks postoperatively. The secondary outcomes are postoperative pain scores, patient satisfaction, quantity of OMEs prescribed and number of opioid refills. Patients are followed at both 2 and 6 weeks postoperatively. Data analysts and outcome assessors are blinded to the treatment groups.

As of December 1, 2021 we have enrolled 166 patients, reaching 83% of target enrolment. Based on the current recruitment rate, we anticipate that enrolment will be completed by the end of January 2022 with final follow-up and study close out completed by March of 2022. The final results will be released at the Canadian Orthopaedic Association Meeting in June 2022 and be presented as follows. The mean difference in OME consumption was XX (95%CI: YY-YY, p=X). The mean difference in OMEs prescribed was XX (95%CI: YY-YY, p=X). The mean difference in Visual Analogue Pain Scores (VAS) and patient satisfaction are XX (95%CI: YY-YY, p=X). The absolute difference in opioid refills was XX (95%CI: YY-YY, p=X).

The results of the current study will demonstrate whether an opioid sparing approach to postoperative outpatient pain management is effective at reducing opioid consumption while adequately addressing postoperative pain in patients undergoing outpatient shoulder and knee arthroscopy. This study is novel in the field of arthroscopic surgery, and its results will help to guide appropriate postoperative analgesic management following these widely performed procedures.

There is no consensus regarding the optimum frequency of ultrasound for monitoring the response to Pavlik harness (PH) treatment in developmental dysplasia of hip (DDH). The purpose of our study was to determine if a limited-frequency hip ultrasound (USS) assessment in children undergoing PH treatment for DDH had an adverse effect on treatment outcomes when compared to traditional comprehensive ultrasound monitoring.

This study was a single-center non-inferiority randomized controlled trial. Children aged less than six months of age with dislocated, dislocatable and stable dysplastic hips undergoing a standardized treatment program with a PH were randomized, once stability had been achieved, to our current standard USS monitoring protocol (every clinic visit) or to a limited-frequency ultrasound protocol (USS only until hip stability and then end of treatment). Groups were compared based on alpha angle at the end of treatment, acetabular indices (AI) and IHDI grade on follow up radiographs at one-year post harness and complication rates. The premise was that if there were no differences in these outcomes, either protocol could be deemed safe and effective.

One hundred patients were recruited to the study; after exclusions, 42 patients completed the standard protocol (SP) and 36 completed the limited protocol (LP). There was no significant difference between the mean age between both groups at follow up x-ray (SP: 17.8 months; LP: 16.6 months; p=0.26). There was no difference between the groups in mean alpha angle at the end of treatment (SP: 69°; LP: 68.1°: p=0.25). There was no significant difference in the mean right AI at follow up (SP: 23.1°; LP: 22.0°; p=0.26), nor on the left (SP:23.3°; LP 22.8°; p=0.59). All hips in both groups were IHDI grade 1 at follow up. The only complication was one femoral nerve palsy in the SP group. In addition, the LP group underwent a 60% reduction in USS use once stable.

We found that once dysplastic or dislocated hips were reduced and stable on USS, a limited- frequency ultrasound protocol was not associated with an inferior complication or radiographic outcome profile compared to a standardized PH treatment pathway. Our study supports reducing the frequency of ultrasound assessment during PH treatment of hip dysplasia. Minimizing the need for expensive, time-consuming and in-person health care interventions is critical to reducing health care costs, improving patient experience and assists the move to remote care. Removing the need for USS assessment at every PH check will expand care to centers where USS is not routinely available and will facilitate the establishment of virtual care clinics where clinical examination may be performed remotely.

Patients awaiting resolution of swelling and oedema prior to ankle surgery can represent a significant burden on hospital beds. Our study assessed whether external pneumatic intermittent compression (EPIC) can reduce delays to surgery.

Our prospective randomised controlled trial (n= 20) compared outcomes of patients treated with EPIC vs control group managed with ice and elevation. Included were patients aged <18 years with isolated closed ankle fractures admitted for management of swelling prior to surgery. Excluded were open fractures, injuries to contralateral leg, diabetes, absent pulses, peripheral vascular disease, inability to consent, no requirement for admission. Eligible patients were randomised to active or control arms. All patients were managed initially with reduction and back slab application. Patients in active arm fitted with EPIC (Hydroven 3000) device over the back slab. Assessment by treating team determined the time at which patient is assessed ready for surgery.

Patients in the treatment arm were assessed as ready for surgery sooner, (123 hrs vs 168hrs, T score = 1.925, P 0.035) and had a shorter time to surgery (167 hrs vs 216 hrs, T score = 1.748, P 0.047) Length of stay was reduced bud did not reach statistical significance. (259 hrs vs 269 hrs, T score 0.229, P 0.41)

Our results showed a statistically and clinically significant reduction in time that patients were assessed ready for surgery and time to surgery in the treatment cohort. We conclude that although further data is needed to achieve an adequately powered study and assess the safety profile of the EPIC, incorporation of EPIC into routine clinical practice has the potential for significant cost savings.

The purpose of this randomized controlled trial was to evaluate serum metal levels in patients undergoing total hip arthroplasty (THA) with a conventional compared to a modular dual-mobility bearing.

Patients undergoing primary THA for osteoarthritis were randomized to receive either a modular dual-mobility or conventional polyethylene bearing. All patients received the same titanium acetabular and femoral component and a ceramic femoral head. Serum metal levels were drawn pre-operatively then annually for a minimum of two years postoperatively. An a priori power analysis determined that 40 patients (20 per cohort) were needed to identify a clinically relevant difference in serum cobalt of 0.35 ng/ml (ppb) at 90% power.

Forty-six patients were randomized to a modular dual-mobility (n=25) or conventional bearing (n=21) with 40 at a minimum follow-up of two years. No differences in serum cobalt (mean 0.14 ppb [range, 0.075–0.29] vs. 0.20 ppb [range, 0.075–0.57], p=0.39) or chromium levels (mean 0.14 ppb [range, 0.05–0.50] vs. 0.12 ppb [range, 0.05–0.35], p=0.65) were identified between the modular dual-mobility and conventional cohorts, respectively.

There was no statistically significant difference in serum Co or Cr at two years postoperatively in subjects implanted with a ceramic head and this particular dual mobility bearing in comparison to a ceramic head and a conventional acetabular component. While modest expected elevations in serum Co and Cr were observed in the dual mobility group, in no case did the Co level exceed the laboratory reference range nor the threshold of one part per billion that has been associated with adverse local tissue reactions to mechanically-assisted crevice corrosion.

Abstract

Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long term survival of cementless implants in total hip arthroplasty (THA). The aim of this study was to examine proximal femoral BMD in three morphologically different uncemented femoral stems designs to investigate whether one particular design resulted in improved preservation of BMD.

119 patients were randomized to receive either a proximally coated dual taper wedge stem, a proximally coated anatomic stem or a fully coated collarless triple tapered stem. Dual energy x-ray absorptiometry scans (Lunar iDXA, GE Healthcare, Madison, WI) assessed BMD across the seven Gruen zones pre-operatively, and post-operatively at 6-weeks, 1-year, and 2-years comparing the unoperated contralateral femur as a control.

BMD increased in zones one (2.5%), two (17.1%), three (13.0%), five (10%) and six (17.9%) for all stems. Greater preservation of BMD was measured on the lateral cortex (zone 2) for both the dual taper wedge and anatomic stems (p = 0.019). The dual taper wedge stem also demonstrated preservation of BMD in the medial calcar (zone 7) whilst the anatomic and triple taper stem declined in this region, however this was not statistically significant (p = 0.059). BMD decreased on average by 2.1% in the mid-diaphysis region, distal to the stem tip (zone 4) for all implants. All stems performed equivalently at final follow-up in all patient reported outcome measures.

Implant design was shown to impact BMD changes. All stems preserved bone at the metaphyseal level in early follow-up, which theoretically indicates favorable implant fixation. There was no significant stress shielding observed, however longer follow-up is required to elucidate the impact of this finding on implant survivorship.