A Systematic Review of Total Knee Arthroplasty in Neurologic Conditions: Survivorship, Complications, and Surgical Considerations.

BACKGROUND: Patients with neurologic disorders present a unique set of challenges for knee surgeons because of contractures, muscle weakness, spasticity, and ligament instability. The primary purpose of this review was to report the outcomes of total knee arthroplasty (TKA) in these patients, including survivorship, complications, and surgical considerations. METHODS: We performed a systematic review of articles using PubMed, Cochrane Central, EMBASE, and Google Scholar. All studies reporting outcomes of TKA in patients with Parkinson disease, multiple sclerosis, poliomyelitis, Charcot joint, spina bifida, stroke, and cerebral palsy were included. RESULTS: In total 38 studies were included: 22 studies (461 patients) reported patient-reported outcome measures and 24 studies (510 patients) reported survivorship. All 38 studies reported complication rates. TKA resulted in an improvement in functional outcome in all series. Complication rate was higher in patients with neurologic conditions. Of studies reporting survivorship, mean follow-up ranged from 1 to 12 years with survivorship from 66% to 100%. All levels of implant constraint were reported without consensus. Limited rehabilitative data exist. CONCLUSION: TKA in patients with neurologic disorders improves symptoms and function but carries significant risk. This review helps surgeons preoperatively counsel their patients in an informed manner. Careful planning, perioperative care, and appropriate implant selection may mitigate risk of complication.

404 Porous titanium revision shells permit early weight-bearing and rapid rehabilitation in revision hip surgery.

An aging population and younger primary arthroplasty candidates have led to increased demand for acetabular bone deficient revision hip surgery. Seventy consecutive revision arthroplasty porous titanium shells prior to December 2011 were reviewed. We sought to determine evidence of implant instability in a cohort of patients that are mobilised early. Radiological data were analysed for stability. Primary endpoint was revision of implant. Mean age at surgery was 69.9 (±10) years. Median time since primary surgery was 13 years (range: 0.3-37). Forty-nine per cent had Paprosky Type IIb or greater acetabular deficiency. Bone graft and augments were not used. One shell was revised for ingrowth failure. Mean acetabular inclination was 35.4 ̊ (±7.3) post- operatively and 36.9 ̊ (±7.28) at latest follow up. There were no screw fractures. Porous titanium shells in revision arthroplasty are stable and permit rapid rehabilitation.

Prevention of Dislocation After Total Hip Arthroplasty.

BACKGROUND: Prevention of dislocation after primary total hip arthroplasty (THA) begins with patient preoperative assessment and planning. METHODS: We performed a literature search to assess historical perspectives and current strategies to prevent dislocation after primary THA. The search yielded 3458 articles, and 154 articles are presented. RESULTS: Extremes of age, body mass index >30 kg/m2, lumbosacral pathology, surgeon experience, and femoral head size influence dislocation rates after THA. There is mixed evidence regarding the effect of neuromuscular disease, sequelae of pediatric hip conditions, and surgical approach on THA instability. Sex, simultaneous bilateral THA, and restrictive postoperative precautions do not influence the dislocation rates of THA. Navigation, robotics, lipped liners, and dual-mobility acetabular components may improve dislocation rates. CONCLUSIONS: Risks for dislocation should be identified, and measures should be taken to mitigate the risk. Reliance on safe zones of acetabular component positioning is historical. We are in an era of bespoke THA surgery.

Dual-Mobility vs Fixed-Bearing Total Hip Arthroplasty in Patients Under 55 Years of Age: A Single-Institution, Matched-Cohort Analysis.

BACKGROUND: Prosthetic dislocation of total hip arthroplasty (THA) is a common cause for revision surgery. Dual-mobility (DM) bearings were introduced to mitigate complications; however, their performance in younger patients is unknown. This study compared results of patients <55 years of age with DM vs fixed-bearing (FB) primary THA. METHODS: Our total joint registry was used to evaluate primary THA patients <55 years of age, and then, an age-matched comparative analysis was performed for 136 THAs using third-generation highly cross-linked polyethylene DM bearings and 136 THAs using FB from the same manufacturer with mean follow-up of 3.2 and 3.4 years, respectively. Mean age at surgery was 48.4 and 48.5 years, respectively. There was no difference in gender distribution. Incidence of complications (eg, dislocation) was evaluated and compared statistically. Patient-reported outcomes using the Modified Harris Hip Score were available. Normally distributed continuous data were compared using the Student t test, and discrete data were compared using the Fisher exact test (P < .05). RESULTS: There were no dislocations or intraprosthetic dissociations (0%) in the DM group and 7 (5.1%) dislocations in the FB group (P = .01) at the mean follow-up of 3 years postoperatively. Two of the 7 unstable patients in the FB cohort were revised for recurrent instability (1.5%). There was no difference in postoperative Modified Harris Hip Score between the DM (87.2 ± 16.6) and the control cohorts (87.9 ± 13.7; P = .78). CONCLUSION: DM bearings in patients <55 years of age show excellent results for prosthetic stability when compared with patients who undergo FB.

Early experience with dual mobility acetabular systems featuring highly cross-linked polyethylene liners for primary hip arthroplasty in patients under fifty five years of age: an international multi-centre preliminary study.

PURPOSE: To evaluate early performance of contemporary dual mobility acetabular systems with second generation annealed highly cross-linked polyethylene for primary hip arthroplasty of patients under 55 years of age. METHODS: A prospective observational five years study across five centers in Europe and the USA of 321 patients with a mean age of 48.1 years was performed. Patients were assessed for causes of revision, hip instability, intra-prosthetic dissociation, Harris hip score and radiological signs of osteolysis. RESULTS: There were no dislocations and no intra-prosthetic dissociations. Kaplan Meier analysis demonstrated 97.51% survivorship for all cause revision and 99.68% survivorship for acetabular component revision at five years. Mean Harris hip score was 93.6. Two acetabular shells were revised for neck-rim implant impingement without dislocation and ten femoral stems were revised for causes unrelated to dual mobility implants. CONCLUSION: Contemporary highly cross-linked polyethylene dual mobility systems demonstrate excellent early clinical, radiological, and survivorship results in a cohort of patients that demand high performance from their implants. It is envisaged that DM and second generation annealed HXLPE may reduce THA instability and wear, the two most common causes of THA revision in hip arthroplasty.

The Oswestry Spinal Risk Index (OSRI): an external validation study.

PURPOSE: The Oswestry Spinal Risk Index (OSRI) was recently reported as an adjunct in the management of metastatic spinal disease. Based on the tumour type and a general condition score, survivorship is predicted. We aimed to externally validate this new score. METHODS: We assessed the survivorship of 121 patients identified from a prospectively collated database in the National Spinal Injuries Unit in the Republic of Ireland. Actual survivorship was calculated according to the tumour subtype and general conditioning, according to the Karnofsky Performance Score (OSRI = Primary Tumour Pathology + (2-General Conditioning Score)). Our results were then compared to those previously published. RESULTS: 45.5 % were female (n = 55). The mean age at presentation was 61.5 years (range 23-85). Breast and prostate cancers were the most frequent diseases encountered. The actual survival in our cohort closely mirrored the predicted survival, according to the equation used to calculate the OSRI with an overall strong correlation found (r = 0.798, p = 0.001). CONCLUSION: We found that the OSRI is a simple to use scoring system. We found a strong correlation in our results with the predicted survivorship based on the OSRI. The OSRI can be used as a useful adjunct in the management of patient with metastatic disease of the spine.

An assessment of the readability and quality of elective orthopaedic information on the Internet.

This study assessed the readability and quality of websites related to; total hip replacement, total knee replacement and anterior cruciate ligament reconstruction using validated instruments. 225 websites were analyzed from Google, Yahoo and Bing. Readability was assessed using the Flesch Reading Ease Score and Flesch-Kincaid grade level. Quality was assessed using the LIDA tool, HON-code status and an original assessment tool. Only 13.7% were set at or below the recommended 6th grade readability level. 27.35% were HON-code certified. There was a wide variation in quality scores between websites and the information relating to the three procedures was inconsistent and generally of poor quality. Given the deficit in information it is important Orthopaedic surgeons provide patients with high quality, readable information or direct them to an appropriate source.

A standardised communication tool reduces radiation exposure associated with intraoperative fluoroscopy.

BACKGROUND: The widespread use of intraoperative fluoroscopy in orthopaedic procedures has revolutionised surgical practice. However, there are risks associated with using ionising radiation. Efforts to reduce radiation exposure include low-dose imaging protocols and lead protective equipment. Current communication during fluoroscopic procedures can be inefficient and lead to excessive radiation exposure for patients and staff. AIMS: This study aims to implement a communication tool with standardised commands to reduce radiation exposure in an Irish orthopaedic department. METHODS: Radiation exposure was evaluated using dose-area product (DAP) measured in uGy/m2. A control group was recorded before implementing the communication tool. Training sessions were conducted and posters of the standardised commands were displayed. Feedback was collected from surgeons and radiographers via surveys. Statistical analysis was performed to compare pre- and post-intervention groups. RESULTS: A total of 673 surgical cases were included over 6 months. The post-intervention group showed a mean reduction in radiation exposure from 59.8 to 36.4 uGy/m2 (p < 0.011). Subset analyses revealed reduced radiation exposure for ORIF of the distal radius, ankle, humerus, and phalanges. Surgeons and radiographers recognised the need for improved communication and expressed willingness to learn the new tool. CONCLUSIONS: Implementation of a standardised communication tool effectively reduced patient and staff radiation exposure. It was also believed to have a positive effect on theatre staff morale. Incorporating a universal language tool into training programmes could be beneficial. Surgeons and radiographers provided several suggestions to improve the effectiveness and implementation of this tool into other units.

RhBMP-2 use in lumbar fusion surgery is associated with transient immediate post-operative leg pain.

PURPOSE: Supra-physiological rhBMP loads during spinal fusion may trigger local inflammation and post-operative radiculitis. MRI is an effective tool to detect nerve root compression in severe post-operative leg pain. The aim of this study was to determine if recombinant bone morphogenic protein 2 (rhBMP-2) is associated with immediate post-operative leg pain without evidence of root compression using MRI. METHOD: All patients undergoing posterolateral and posterior interbody lumbar spinal fusions with rhBMP-2 between July 2007 and January 2009 at a single surgeon practice were retrospectively reviewed for incidence of severe immediate post-operative leg pain. Patients that presented with immediate post-operative leg pain were interviewed and Oswestry Disability Indices calculated. RESULTS: Sixty-four rhBMP-2 treated patients and 40 controls were included. Pre-operative demographics and diagnoses were similar and inter-body cages were used equally. Immediate post-operative leg pain incidence was 25 and 12.5% in the rhBMP-2 and non-rhBMP-2 groups, respectively. 17.2% of the patients treated with rhBMP-2 had immediate post-operative leg pain without evidence of nerve root compression on MRI versus 7.5% of the patients treated without rhBMP-2. At follow-up, leg pain incidence was 11.6 and 7.6% in rhBMP-2 and non-rhBMP-2 groups, respectively. There was no difference in Oswestry Disability Indices between groups (36.5 ± 31.2 vs. 23.0 ± 25.5). CONCLUSION: RhBMP-2 associated radiculitis presenting as immediate post-operative leg pain without MRI evidence of neuronal compression occurs in 17% of the patients with rhBMP-2 assisted fusion. Patients should be pre-operatively counselled regarding immediate post-operative leg pain with rhBMP-2. LEVEL OF EVIDENCE: III.

Weight-bearing Allowed Following Internal Fixation of Ankle Fractures, a Systematic Literature Review and Meta-Analysis.

BACKGROUND: Postoperative management regimes vary following open reduction and internal fixation of unstable ankle fractures. Traditional postoperative nonweightbearing cast immobilization may prevent loss of fixation and protect the soft tissue envelope but may also be associated with poorer functional outcomes. This systematic review and meta-analysis aimed to compare the complication rate and functional outcomes of early weightbearing (EWB) vs late weightbearing (LWB) following open reduction and internal fixation of ankle fractures. METHODS: We performed a systematic review with a meta-analysis of controlled trials and comparative cohort studies using 3 databases. We included all studies that investigated the effect of weightbearing following internal fixation of ankle fractures in adult patients by any means. Studies that investigated mobilization but not weightbearing, non-English-language publications, and tibial Plafond fractures were excluded from this systematic review. We assessed the risk of bias using ROB 2 tools for randomized controlled trials and ROBINS-1 for cohort studies. Data extraction was performed using Covidence online software and meta-analysis by using RevMan 5.3. RESULTS: This systematic review included 10 randomized controlled trials and 4 comparative cohort studies. Most of the included studies were rated as having some concern with regard to the risk of bias. There was no significant difference in the complication rate between the protected EWB and LWB groups (the risk ratio [RR] for infection was 1.30, 95% CI 0.74, 2.30; I² = 0%; P = .36), but better functional outcome scores were detected in the EWB group only at 6 weeks postoperatively (MD =10.08, 95% CI 5.13, 15.02; I² = 0%; P ≤ .0001), with no significant difference seen at 6 or 12 months postoperatively. CONCLUSION: Based on the studies reviewed, it appears that early protected weightbearing following open reduction and internal fixation of ankle fractures does not affect surgical incision or fracture healing and is associated with better early functional outcomes at 6 weeks, but not 6 or 12 months, postoperatively.

Subsidence of monoblock and modular titanium fluted tapered stems in revision hip arthroplasty: A retrospective multicentre comparison study.

Background: Tapered, fluted, titanium (TFT) stems have shown good clinical outcomes in revision total hip arthroplasty (rTHA), however concerns exist regarding early subsidence. This study compares subsidence between a modern monoblock 3-degree and a modular 2-degree TFT stem in rTHA. Methods: A retrospective, international multicentre comparative study was conducted including 64 rTHA in 63 patients. A monoblock TFT stem was used in 37 cases and a modular TFT stem was used in 27 cases. Patient demographics, Paprosky femoral bone loss classification, bicortical contact and stem subsidence were recorded at minimum four week follow up. Results: There was no statistically significant difference in overall subsidence (p = 0.318) or the rate of subsidence >10 mm between stems. Mean subsidence was 2.13 mm in the monoblock group and 3.15 mm in the modular group. Two stems subsided >10 mm: one in each group. There was no difference in bicortical contact between groups (p = 0.98). No re-revisions were performed. Conclusions: We found no difference in subsidence between the two stems. Surgeons may consider the use of monoblock stems in rTHA as they have comparably low rates of subsidence and eliminate the small but potentially catastrophic risk of implant fracture at modular junctions associated with modular stems.

Short-term outcomes of total knee arthroplasty performed with and without a tourniquet.

INTRODUCTION: Not using a tourniquet could improve early postoperative pain, range of motion (ROM), length of stay (LOS), and thromboembolic risk in patients undergoing total knee arthroplasty (TKA). Our aim was to compare these factors, intraoperative blood loss, and gender-related outcomes in patients undergoing primary TKA with or without a tourniquet. METHODS: We performed a retrospective cohort study of 97 patients undergoing TKA with or without tourniquet from 2018 to 2020. Revisions and bilateral TKAs were excluded. Blood loss was estimated using a validated formula. Postoperative pain was tested using the visual analogue scale (VAS). ROM and quadriceps lag were assessed by a physiotherapist on a postoperative day 2 and discharge. The index of suspicion for a thromboembolic event was defined as the number of embolic-related investigations ordered in the first 6 months post-surgery. The Shapiro-Wilk test was used to assess the distribution of the data, Mann-Whitney for the continuous variables, and Fischer's test for the categorical ones. RESULTS AND DISCUSSION: There was a significant difference in blood loss. The non-tourniquet group lost on average 32% more blood (1291 mL vs. 878 mL, p<0.001 two-tailed). We found no difference in pain, ROM, LOS, and quadriceps lag on day 2 and at discharge. There was one thromboembolic event in the tourniquet group, but the thromboembolic index of suspicion did not differ (p=0.53). With tourniquet use, women had a significantly lower day 2 maximum flexion than men (71.56° vs. 84.67°, p=0.02). In this retrospective cohort study, the results suggest that tourniquet use is associated with lower blood loss and similar postoperative pain, range of motion, quadriceps lag, length of stay, and thromboembolic risk. There might be some differences between how men and women tolerate a tourniquet, with women having worse short-term outcomes compared to men.

Incidence and Risk Factors for the Development of Acute Colonic Pseudo-Obstruction (Ogilvie Syndrome) in Total Joint Arthroplasty Patients.

BACKGROUND: Acute colonic pseudo-obstruction (Ogilvie syndrome [OS]) is a rare but devastating condition that can develop in orthopaedic patients postoperatively. The objective of this study was to identify the risk factors for developing OS after total hip arthroplasty (THA) or total knee arthroplasty (TKA) and to compare the outcomes between patients who did and did not develop OS postoperatively. METHODS: This was a retrospective review using the National Inpatient Sample, a national database incorporating inpatient hospitalization information. ICD-9 codes were used to identify patients who underwent primary and revision THA or TKA. Patients were separated based on the diagnosis of OS. Primary outcomes assessed included patient mortality, postoperative complications, length of stay, and cost during index hospitalization. RESULTS: From 2001 to 2014, a total of 12,541,169 patients underwent primary and revision THA or TKA. Of those, 3,182 patients (0.03%) developed OS postoperatively. There was an increased incidence of OS in revision THA and TKA compared with primary THA and TKA. Fluid and electrolyte disorders were associated with the largest increased adjusted risk of OS. Patients with OS had an increased adjusted risk of overall postoperative complications and being discharged to skilled nursing facility. Patients with OS had an increased average length of stay and hospitalization cost compared with patients without OS. DISCUSSION: Given our findings, the risk factors for the development of OS, including revision surgery, should be identified and minimized during the perioperative period to prevent the development of this morbid and potentially life-threatening complication. LEVEL OF EVIDENCE: III (Retrospective cohort study).

Is postoperative non-weight-bearing necessary? INWN Study protocol for a pragmatic randomised multicentre trial of operatively treated ankle fracture.

BACKGROUND: Postoperative management regimes vary following open reduction and internal fixation (ORIF) of unstable ankle fractures. There is an evolving understanding that extended periods of immobilisation and weight-bearing limitation may lead to poorer clinical outcomes. Traditional non-weight-bearing cast immobilisation may prevent loss of fixation, and this practice continues in many centres. The purpose of this trial is to investigate the safety and efficacy of immediate weight-bearing (IWB) and range of motion (ROM) exercise regimes following ORIF of unstable ankle fractures with a particular focus on functional outcomes and complication rates. METHODS: A pragmatic randomised controlled multicentre trial, comparing IWB in a walking boot and ROM within 24 h versus non-weight-bearing (NWB) and immobilisation in a cast for 6 weeks, following ORIF of all types of unstable adult ankle fractures (lateral malleolar, bimalleolar, trimalleolar with or without syndesmotic injury) is proposed. All patients presenting to three trauma units will be included. The exclusion criteria will be skeletal immaturity and tibial plafond fractures. The three institutional review boards have granted ethical approval. The primary outcome measure will be the functional Olerud-Molander Ankle Score (OMAS). Secondary outcomes include wound infection (deep and superficial), displacement of osteosynthesis, the full arc of ankle motion (plantar flexion and dorsal flection), RAND-36 Item Short Form Survey (SF-36) scoring, time to return to work and postoperative hospital length of stay. The trial will be reported in accordance with the CONSORT statement for reporting a pragmatic trial, and this protocol will follow the SPIRIT guidance. DISCUSSION: Traditional management of operatively treated ankle fractures includes an extended period of non-weight-bearing. There is emerging evidence that earlier weight-bearing may have equivocal outcomes and favourable patient satisfaction but higher wound-related complications. These studies often preclude more complicated fracture patterns or patient-related factors. To our knowledge, immediate weight-bearing (IWB) following ORIF of all types of unstable ankle fractures has not been investigated in a controlled prospective manner in recent decades. This pragmatic randomised-controlled multicentre trial will investigate immediate weight-bearing following ORIF of all ankle fracture patterns in the usual care condition. It is hoped that these results will contribute to the modern management of ankle fractures. TRIAL REGISTRATION: ISRCTN Registry ISRCTN76410775 . Retrospectively registered on 30 June 2019.

Single 3° tapered fluted femoral stems demonstrate low subsidence at mid-term follow-up in severe bony deficiency.

BACKGROUND: Tapered femoral stems have become popular in revision total hip arthroplasty (rTHA). Increasing the distal taper angle may mitigate subsidence. This study reports osseointegration of a new 3 degree distal taper revision stem at minimum 4 years post-operatively. METHODS: Indication for surgery, pre-operative bony deficiency and latest clinical, tribological and radiological follow-up were analysed. Radiographs were assessed by two blinded observers for preoperative femoral bone stock according to Paprosky, postoperative subsidence according to Callaghan and restoration of femoral bone stock over time according to Kolstad. Stem integration was determined using the Rodriguez classification. RESULTS: Twenty-three cases were analyzed at 5.9±1.0 years. All patients presented with Paprosky III defects. All stems met the criteria for osseointegration. Spot welds occurred distal to the proximal modular junction and at the tip. Two femora with severe proximal femoral bone loss recovered bone stock by final follow-up but two demonstrated stress shielding. No intraoperative fractures occurred. One stem subsided early but remained stable and osseointegrated at final follow up. There were no stem failures due to taper corrosion or modular junctional failure. CONCLUSIONS: This study reports good osseointegration and low subsidence with a novel fluted, 3-degree tapered femoral stem demonstrates at medium-term follow-up in cases with severe femoral bone deficiency.

Self-Directed Oral Vitamin D Supplementation in Professional Ballet Dancers: A Randomized Controlled Trial Pilot Study.

Inadequate levels of vitamin D may lead to poor performance in professional dancers. Therefore, dietary supplementation may be essential in this population. This longitudinal pilot study to a randomized controlled trial assessed dancer compliance with self-directed oral vitamin D supplementation. Seventy-one dancers, 41 females and 30 males with a mean age of 31.1 years, were recruited from The Royal Ballet, London. Baseline serum 25(OH)D levels were measured and dancers were interviewed, examined, and provided with oral supplements for the winter period, November 2011 to March 2012. Dancers with normal serum 25(OH)D levels were provided with maintenance supplements (1,000 IU/ day) and those with insufficient or deficient serum 25(OH)D levels were given a loading dose of 60,000 IU weekly for 2 and 6 weeks, respectively. Serum 25(OH) D levels were measured at 1 and 2 years and dancers were sampled for compliance with instructions. Mean compliance during loading and maintenance was 86% and 50%, respectively. Mean serum 25(OH)D levels at start and end of the study period were 79.3 ± 31.6 nmol/L and 78.68 ± 19.8 nmol/L, respectively. Only one-third of dancers with insufficient (N = 5) and deficient (N = 5) serum vitamin D levels improved to normal values. It is concluded that professional ballet dancers demonstrate good compliance with self-directed loading doses of vitamin D supplementation but poor compliance with maintenance doses. Poor maintenance compliance may have accounted for the low rates of serum vitamin D level improvement among dancers with insufficient or deficient levels.

The Role of One-Stage Exchange for Prosthetic Joint Infection.

PURPOSE OF REVIEW: In an era of increasing numbers of hip and knee replacements, strategies to manage prosthetic joint infection (PJI) that are effective at infection control with good patient-reported outcomes and cost containment for health systems are needed. Interest in single-stage exchange for PJI is rising and we assess evidence from the last 5 years related to this treatment strategy. RECENT FINDINGS: Only five series for total knee replacement and ten series for total hip replacement have been reported in the last five years. More review articles and opinion pieces have been written. Reinfection rates in these recent studies range from 0 to 65%, but a meta-analysis and systematic review of all studies showed a reinfection rate of 7.6% (95% CI 3.4-13.1) and 8.8% (95% CI 7.2-10.6) for single-stage and two-stage revisions respectively. There is emerging evidence to support single-stage revision in the setting of significant bony deficiency and atypical PJIs such as fungal infections. Prospective randomised studies are recruiting and are necessary to guide the direction of single-stage revision selection criteria. The onus of surgical excellence in mechanical removal of implants, necrotic tissue, and biofilms lies with the arthroplasty surgeon and must remain the cornerstone of treatment. Single-stage revision may be considered the first-line treatment for all PJIs unless the organism is unknown, the patient is systemically septic, or there is a poor tissue envelope.

The onset of fretting at the head-stem connection in hip arthroplasty is affected by head material and trunnion design under simulated corrosion conditions.

Mechanically assisted crevice corrosion (MACC) is a mechanism for trunnion damage in total hip arthroplasties (THAs). Retrieval studies have shown reduced MACC-related damage for ceramic heads compared with cobalt-chromium (CoCr) heads. We propose that ceramic heads demonstrate fretting at higher cyclic compressive loads than CoCr heads on titanium alloy trunnions in a simulated corrosion model. A closed electrochemical chamber was used to measure fretting current onset loads for two modern titanium alloy trunnions (Zimmer 12/14 and Stryker V-40) in which trunnion failure has been reported. Ceramic and CoCr alloy 36 + 0 mm heads were impacted on each trunnion and cyclically loaded at 3 Hz with increasing magnitude from 100 to 3,400 N for 540 cycles. Onset load was the cyclic compressive load at which the slope of the average fretting current increased significantly. A CoCr head with V40 trunnion demonstrated the lowest onset load (1,400 N), while the V40 trunnion with a ceramic head showed the highest onset load (2,200 N). Significant differences occurred in average fretting current between head materials for V40 trunnions (p < 0.001) at loads over 2,000 N. CoCr-12/14 and ceramic-12/14 couples demonstrated similar onset loads (2,000 N). All head-trunnion combinations showed cyclical fretting response to loading at 100 N. Head material composition was observed to increase fretting at the taper junction but the effect was taper geometry dependent. Using ceramic heads may reduce the phenomena of trunnion fretting and corrosion but the effect of both trunnion geometry and metallurgy warrants further investigation. Statement of clinical significance: Trunnion corrosion may occur with titanium alloy stems regardless of the head material used. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1630-1636, 2018.

A comparison of acetabular impaction grafting and trabecular metal for revision arthroplasty.

BACKGROUND: Acetabular defect reconstruction in revision hip arthroplasty may be achieved with acetabular impaction bone grafting (AIBG) or porous trabecular metal (TM) implantation. We sought to compare clinical and radiological outcomes of both methods at a single institution. METHODS: 36 patients that were revised using AIBG and 17 patients that were revised with TM were retrospectively reviewed from local joint registry data. 82% of the TM group and 64% of the AIBG group were ≥ Paprosky 2c. Rerevision was considered failure. Radiographs demonstrating 5 mm of migration of femoral head and 5° of acetabular component inclination change were considered loose. RESULTS: Age at surgery was earlier in the AIBG group (median 68 years vs. 74 years). Median follow-up was 5.9 years for AIBG and 5.4 years for TM. Harris Hip Scores improved significantly for both groups (mean improvement: 32 vs. 31). There were 4 failures (11%) in the AIBG group and none in the TM group. 3 of the 4 AIBG failures occurred following second-stage revision for prosthetic joint infection. 4 (11%) and 2 (12%) hip reconstructions demonstrated radiological evidence of loosening in AIBG and TM groups respectively. CONCLUSIONS: AIBG and TM acetabular defect reconstructions achieve good clinical outcome but there is greater success with TM in higher grades of acetabular deficiency regardless of prior infection.