Prevalence of extra-articular tibia valga morphology in valgus knees and its implications for primary total knee arthroplasty.

INTRODUCTION: Tibia valga, an extra-articular valgus deformity of the tibia, is common in valgus knees and can result in component misplacement and early total knee arthroplasty (TKA) failure. However, the prevalence and importance of tibia valga in TKA have been seldom reported. This study aims to describe the prevalence and characteristics of tibia valga morphology in valgus knees and describe implications for surgical planning in primary TKA. METHODS: We prospectively examined pre-operative weightbearing whole-body EOS digital radiographs of patients with knee osteoarthritis listed for TKA between December 2018 and December 2020. Hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), joint line convergence angle (JLCA) and tibial morphology with centre of rotation of angulation of tibia (CORA-tibia) were measured and analysed. RESULTS: In 830 knees, 253 (30%) and 577 (70%) were classified as valgus and varus, respectively. In valgus knees, 89 knees (35%) had tibia valga. Median CORA-tibia was 2.8° (range 0.2°-10.9°). Tibia valga knees had no difference in mLDFA, higher HKA (5.0o versus 3.0°, p = 0.002) and mMPTA (89.6° versus 88.1°, p < 0.01), and lower JLCA (2.1° versus 2.3°, p < 0.01) compared to non-tibia valga knees. Tibia valga deformity was weakly positively correlated with valgus HKA (ρ = 0.23, p < 0.001) and mMPTA (ρ = 0.38, p < 0.001). In varus knees, there were 52 cases of tibia valga (9%) with median CORA-tibia of 3.0° (range 0.5°-5.5°). Tibia valga knees had higher mMPTA (87.0° versus 85.2°, p < 0.05) and no difference in HKA, mLDFA and JLCA. CORA-tibia was weakly positively correlated with mMPTA. CONCLUSIONS: Valgus knees may have an extra-articular deformity of the tibia which might be the primary contributor of the overall valgus HKA deformity rather than the distal femoral anatomy. To detect the deformity, full leg-length radiographs should be acquired pre-operatively. Intramedullary instrumentation should be used cautiously in knees with tibia valga when performing TKA.

Accuracy of one-dimensional templating on linear EOS radiography allows template-directed instrumentation in total knee arthroplasty.

BACKGROUND: Templating for total knee arthroplasty (TKA) is routinely performed on two-dimensional standard X-ray images and allows template-directed instrumentation. To date, there is no report on one-dimensional (1D) anteroposterior (AP) templating not requiring specific templating software. We aim to describe a novel technique and explore its reliability, accuracy and potential cost-savings. METHODS: We investigated a consecutive series of TKAs at one institution between January and July 2019. Patients with preoperative low-dose linear AP EOS radiography images were included. Implant component sizes were retrospectively templated on the AP view with the hospitals imaging viewing software by two observers who were blinded to the definitive implant size. Planning accuracy as well as inter- and intra-observer reliability was calculated. Cost-savings were estimated based on the reduction of trays indicated by the 1D templating size estimations. RESULTS: A total of 141 consecutive TKAs in 113 patients were included. Accuracy of 1D templating was as follows: exact match in 53% femoral and 63% tibial components, within one size in 96% femoral and 98% tibial components. Overall 58% of TKA components were planned correctly and 97% within one size. Inter- and intra-rater reliability was good (κ = 0.66) and very good (κ = 0.82), respectively. This templating process can reduce instrumentation from six to three trays per case and therefore halve sterilisation costs. CONCLUSIONS: The new 1D templating method using EOS AP imaging predicts component sizes in TKA within one size 97% of the time and can halve the number of instrumentation trays and sterilisation costs.

Erector spinae plane block combined with local infiltration analgesia for total hip arthroplasty: A randomized, placebo controlled, clinical trial.

The erector spinae plane block is an emerging analgesic technique, which is gaining popularity for a large number of procedures. The majority of publications are at the thoracic level and almost all indicate some benefit to patients. However, there have been relatively few randomized controlled trials and even fewer studies at the lumbar level. The aim of this study was to assess whether the erector spinae plane block at the lumbar level would confer early analgesic benefits and improve the quality of recovery in patients undergoing elective unilateral primary hip arthroplasty. Sixty-four patients were randomized to receive an erector spinae plane block at the third lumbar vertebra with either 30milliliters (ml) of 0.2% ropivacaine or 30 ml of 0.9% saline. The patient, anesthetist and assessor were blinded to allocation. The primary outcome was pain on movement at 6 h (numeric rating scale 0-10) with a reduction of 2 points considered clinically significant. Secondary outcomes included quality of recovery (QoR-15 score), mobilization and length of stay. In this study there was no appreciable analgesic benefit to adding an erector spinae plane block to patients who already receive neuraxial blocks, local anesthetic infiltration and oral multimodal analgesia for elective primary total hip arthroplasty. Both groups were found to have relatively low pain scores and a high quality of recovery with no significant difference in mobilization or length of stay.

Cementless Versus Cemented Tibial Fixation in Posterior Stabilized Total Knee Replacement: A Randomized Trial.

BACKGROUND: Evidence supports the use of cementless tibial component fixation in total knee replacement but there is a paucity of literature on posterior stabilized designs. This randomized study of posterior stabilized total knee replacements compared cemented and cementless tibial fixation with regard to component migration, bone remodeling, and clinical outcomes. METHODS: This prospective single-center, blinded, randomized clinical trial included 100 patients with a mean age of 68 years (range, 45 to 87 years). Operations were performed by either of 2 experienced arthroplasty surgeons using the Advanced Coated System (ACS) prosthesis (Implantcast). Patients were randomized to cemented or cementless tibial fixation; other variables were standardized. Radiostereometric analysis (RSA) and dual x-ray absorptiometry (DXA) were performed during the inpatient stay and at 3, 12, and 24 months to monitor tibial component migration and periprosthetic bone mineral density (BMD). Clinical scores including the Oxford Knee Score and Short Form-12 were assessed prior to surgery and during follow-up. RESULTS: Late and continuing migration was found with cementless fixation. At 24 months, the mean subsidence was significantly greater for the cementless group (1.22 mm) compared with the cemented group (0.06 mm) (p < 0.01). The mean maximum total point motion at 24 months was 2.04 mm for the cementless group and 0.48 mm for the cemented group (p < 0.01). The cemented group had more BMD loss than the cementless group in the medial, lateral, and anterior periprosthetic regions. Two tibial components were revised in the cementless group, including 1 for loosening. Clinical scores improved equally in the 2 groups. CONCLUSIONS: Late ongoing subsidence and high maximum total point motion in our patients who underwent cementless tibial fixation raise concerns about the fixation stability of ACS cementless posterior stabilized knee replacements. Cemented tibial components were stable. Thus, we advise caution regarding the use of cementless tibial components and recommend tibial fixation with cement for the ACS posterior stabilized total knee replacement. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Thermal Assessment of Ex Vivo Laser Ablation of Cortical Bone.

As a potential osteotomy tool, laser ablation is expected to provide rapid machining of bone, while generating minimal thermal damage (carbonization) and physical attributes within the machined region conducive to healing. As these characteristics vary with laser parameters and modes of laser operation, the clinical trials and in vivo studies render it difficult to explore these aspects for optimization of the laser machining parameters. In light of this, the current work explores various thermal and microstructural aspects of laser-ablated cortical bone in ex vivo study to understand the fundamentals of laser-bone interaction using computational modeling. The study employs the Yb-fiber Nd:YAG laser (λ = 1064 nm) in the continuous wave mode to machine the femur section of bovine bone by a three-dimensional machining approach. The examination involved thermal analysis using differential scanning calorimetry and thermogravimetry, phase analysis using X-ray diffractometry, qualitative analysis using X-ray photoelectron spectroscopy, and microstructural and semiquantitative analysis using scanning electron microscopy equipped with energy-dispersive spectrometry. The mechanism of efficient bone ablation using the Nd:YAG laser was evaluated using the computational thermokinetics outcome. The use of high laser fluence (10.61 J/mm2) was observed to be efficient to reduce the residual amorphous carbon in the heat-affected zone while achieving removal of the desired volume of the bone material at a rapid rate. Minimal thermal effects were predicted through computational simulation and were validated with the experimental outcome. In addition, this work reveals the in situ formation of a scaffold-like structure in the laser-machined region which can be conducive during healing.

Evolution of surface morphology of Er:YAG laser-machined human bone.

The extensive research on the laser machining of the bone has been, so far, restricted to drilling and cutting that is one- and two-dimensional machining, respectively. In addition, the surface morphology of the laser machined region has rarely been explored in detail. In view of this, the current work employed three-dimensional laser machining of human bone and reports the distinct surface morphology produced within a laser machined region of human bone. Three-dimensional laser machining was carried out using multiple partially overlapped pulses and laser tracks with a separation of 0.3 mm between the centers of consecutive laser tracks to remove a bulk volume of the bone. In this study, a diode-pumped pulse Er:YAG laser (λ = 2940 nm) was employed with continuously sprayed chilled water at the irradiation site. The resulting surface morphology evolved within the laser-machined region of the bone was evaluated using scanning electron microscopy, energy dispersive spectroscopy, and X-ray micro-computed tomography. The distinct surface morphology involved cellular/channeled scaffold structure characterized by interconnected pores surrounded by solid ridges, produced within a laser machined region of human structural bone. Underlying physical phenomena responsible for evolution of such morphology have been proposed and explained with the help of a thermokinetic model.

The Influence of Obesity on Hip Pain, Function, and Satisfaction 10 Years Following Total Hip Arthroplasty.

BACKGROUND: The prevalence of obesity is rising, and increasing numbers of joint arthroplasty surgeries are being performed on obese patients. Concern exists that obesity increases surgical risk; however, its impact on function following total hip arthroplasty (THA) is inconsistently affirmed and less understood. A paucity exists in the literature pertaining long-term objective functional measures. Therefore, we investigated the impact of obesity on hip pain, function, and satisfaction 10 years following THA. METHODS: This single-center, prospective, observational study categorized consecutive THA patients according to their body mass index to nonobese (<30 kg/m2) and obese (≥30 kg/m2) groups. Preoperative assessment included a numerical pain rating and the Oxford Hip Score. These were repeated along with a 6-minute walk test and a Likert satisfaction scale at 3 months, 1, 5, and 10 years postoperatively. RESULTS: The series included 191 primary THA patients. No significant differences were found in hip pain or function between the obese and nonobese groups. Obese patients however had poorer walking capacity (P = .008), were more likely to use walking aids (P = .04), and were less satisfied (P = .04) at 10 years. CONCLUSION: THA confers significant long-term symptom resolution irrespective of obesity; however, despite undergoing surgery, obese patients can be counseled they may not be as satisfied as or achieve the same walking capacity as nonobese individuals.

Randomised clinical trial assessing migration of uncemented primary total hip replacement stems, with and without autologous impaction bone grafting.

PURPOSE: Uncemented stems in primary total hip replacement (THR) are concerning in the elderly due to ectatic femoral canals and cortical thinning resulting in higher incidence of fracture and subsidence in this population. To obviate this concern, the authors developed a technique using autologous impaction bone grafting to achieve a better fitting femoral stem. The aim of this randomised clinical trial was to assess the efficacy of the technique. METHODS: From 2013 to 2015, a total of 98 consecutive participants (100 primary THR procedures) were inducted into a single-institution, single-blinded, randomised clinical trial assessing, with radiostereometric analysis (RSA), the efficacy of autologous impaction bone grafting in uncemented primary THR compared with traditional uncemented primary THR technique. The primary outcome measure was femoral component migration using RSA. Secondary outcomes were post-operative proximal femoral bone density (using DEXA), hip function and quality of life using Oxford Hip Score (OHS) and Short Form-12 Health Survey (SF-12), hip pain and patient satisfaction. RESULTS: There was no difference in femoral component stability (p > 0.5) or calcar resorption between the Graft and No Graft Groups at two years. There was also no difference in OHS, SF-12, pain or satisfaction between the Graft and No Graft Groups at two years (p > 0.39). CONCLUSIONS: Autologous impaction bone grafting in uncemented primary THR has shown its short-term post-operative outcomes to be equivalent to standard uncemented technique, whilst offering a better fit in patients who are between femoral stem sizes. AUSTRALIAN CLINICAL TRIAL REGISTRATION NUMBER: ACTRN12618000652279.

Factors influencing return to work after hip and knee arthroplasty.

BACKGROUND: A substantial proportion of patients undergoing lower limb arthroplasty are of working age. This study aims to identify when patients return to work (RTW) and if they return to normal hours and duties, and to identify which factors influence postoperative RTW. The hypothesis is that there is no difference in time of RTW between the different types of surgery, and no difference in time of RTW based on the physical demands of the job. MATERIALS AND METHODS: Consecutive patients aged < 65 years who had undergone unilateral primary total hip arthroplasty (THA), total knee arthroplasty (TKA), or medial unicompartmental knee arthroplasty (UKA) from 2015 to 2017 were sent a questionnaire. Quantitative questions explored timing and nature of RTW, and qualitative questions explored factors influencing timing of RTW. RESULTS: There were 116 patients (64 male, 52 female) with an average age of 56 years. Thirty-one patients were self-employed and 85 were employees. Of these patients, 58 had undergone THA, 31 had undergone TKA, and 27 had undergone UKA. One hundred and six (91%) patients returned to work. Patients returned to work after (mean) 6.4 weeks (THA), 7.7 weeks (TKA), and 5.9 weeks (UKA). Time of RTW was not significantly influenced by type of surgery (p = 0.18) (ns). There was a non-significant correlation between physical demands of the work versus time of RTW (p = 0.28) (ns). There was a significantly earlier time of RTW if flexible working conditions were resumed (p = 0.003). Active recovery, motivation, necessity and job flexibility enabled RTW. The physical effects of surgery, medical restrictions and work factors impeded RTW. CONCLUSION: The time of RTW was not significantly influenced by the type of operation or by the physical demands of the job. Patients returned to work 5.9-7.7 weeks after hip/knee arthroplasty. Rehabilitation, desire, and necessity promoted RTW. Pain, fatigue and medical restrictions impeded RTW. LEVEL OF EVIDENCE: 3.

Piriformis-Sparing Minimally Invasive Versus the Standard Posterior Approach for Total Hip Arthroplasty: A 10-Year Follow-Up of a Randomized Control Trial.

BACKGROUND: Despite the popularity of minimally invasive approaches in total hip arthroplasty, studies regarding their impact on soft tissues and long-term benefits are lacking. This study aims to compare the 10-year functional outcome of the piriformis-sparing minimally invasive approach to the standard posterior approach for total hip arthroplasty surgery. METHODS: Hundred patients were randomized, 48 patients to the piriformis-sparing approach and 52 to the standard approach. Primary outcomes were hip function and piriformis muscle volume and grade on magnetic resonance imaging. Secondary outcomes were pain, satisfaction score, and complications. Evaluators were blinded to allocation. Participants were followed up to 10 years. RESULTS: Ten years following surgery, both groups reported excellent pain relief, improved hip function, and high satisfaction. The significant differences were improvement in piriformis muscle volume (P = .001) and muscle grade (P = .007) in the piriformis-sparing group compared to the standard group. There were no significant differences in all other outcomes. CONCLUSION: Aside from being less injurious to the piriformis muscle, the piriformis-sparing approach offered the same long-term functional benefits as the standard posterior approach at 10 years.

Smartphone technology: a reliable and valid measure of knee movement in knee replacement.

Knee range of motion (ROM) following a knee arthroplasty is an important clinical outcome that directly relates to the patient's physical function. Smartphone technology has led to the creation of applications that can measure ROM. The aim was to determine the concurrent reliability and validity of the photo-based application 'Dr Goniometer' (DrG) compared with a universal goniometer performed by a clinician. A smartphone camera was used to take photographs of the knee in full flexion and full extension, and the images were sent by participants to a study phone. Participants then rated the ease of participation. To assess validity, the patient's knee was measured by a clinician using a goniometer. To examine reliability, four clinicians assessed each image using DrG on four separate occasions spaced 1 week apart. A total of 60 images of knee ROM for 30 unicondylar or total knee arthroplasty were assessed. The goniometer and DrG showed strong correlations for flexion (r=0.94) and extension (r=0.90). DrG showed good intrarater reliability and excellent inter-rater reliability for flexion (intraclass correlation coefficient=0.990 and 0.990) and good reliability for extension (intraclass correlation coefficient=0.897 and 0.899). All participants found the process easy. DrG was proven to be a valid and reliable tool in measuring knee ROM following arthroplasty. Smartphone technology, in conjunction with patient-reported outcomes, offers an accurate and practical way to remotely monitor patients. Benefit may be found in differentiating those who need face-to-face clinical consult to those who do not.

Solid Cup vs Cluster Hole in Total Hip Arthroplasty: A 10-Year Randomized Control Trial.

BACKGROUND: Acetabular osteolysis is a major complication of total hip arthroplasty. It is caused in part by wear debris. It has been suggested that this debris can migrate through screw holes in the acetabular component. Solid-backed components have been used to prevent this migration and reduce osteolysis. Newer materials, however, have reduced wear debris. This study aimed to evaluate whether using solid-backed instead of cluster-hole components actually reduces osteolysis. This could open up the possibility of screws being used for greater stability where required. METHODS: This prospective trial randomized 100 patients undergoing cementless total hip arthroplasty to receive either cluster-hole or solid-backed acetabular components. A cementless cup and highly cross-linked polyethylene was used in all patients. Computed tomography, performed at 5 and 10 years after surgery, was assessed by a blinded radiologist for the presence of osteolysis. RESULTS: Of the 100 patients, 14 required screws for stability, and so were moved into a third "screw" group for per-protocol analysis. At 10 years after surgery, osteolytic lesions were discovered in 18.2% of patients. There was no difference in incidence or volume of osteolysis between patients with cluster-hole acetabular components and those with solid-backed components. CONCLUSION: This study reveals a low number of patients with osteolytic lesions 10 years after total hip arthroplasty performed with a modern cup design and highly cross-linked polyethylene liner. There was no clear benefit to using solid-backed acetabular components. Cluster-hole components, however, offer the option of screw augmentation when required.

Integrated experimental and computational approach to laser machining of structural bone.

This study describes the fundamentals of laser-bone interaction during bone machining through an integrated experimental-computational approach. Two groups of laser machining parameters identified the effects of process thermodynamics and kinetics on machining attributes at micro to macro. A continuous wave Yb-fiber Nd:YAG laser (wavelength 1070 nm) with fluences in the range of 3.18 J/mm2-8.48 J/mm2 in combination of laser power (300 W-700 W) and machining speed (110 mm/s-250 mm/s) were considered for machining trials. The machining attributes were evaluated through scanning electron microscopy observations and compared with finite element based multiphysics-multicomponent computational model predicted values. For both groups of laser machining parameters, experimentally evaluated and computationally predicted depths and widths increased with increased laser energy input and computationally predicted widths remained higher than experimentally measured widths whereas computationally predicted depths were slightly higher than experimentally measured depths and reversed this trend for the laser fluence >6 J/mm2. While in both groups, the machining rate increased with increased laser fluence, experimentally derived machining rate remained lower than the computationally predicted values for the laser fluences lower than ∼4.75 J/mm2 for one group and ∼5.8 J/mm2 for other group and reversed in this trend thereafter. The integrated experimental-computational approach identified the physical processes affecting machining attributes.

Patient Dissatisfaction Following Total Knee Arthroplasty: A Systematic Review of the Literature.

BACKGROUND: Dissatisfaction following total knee arthroplasty (TKA) is common. Approximately 20% of patients report dissatisfaction following primary TKA. This systematic literature review explores key factors affecting patient dissatisfaction following TKA. METHODS: Six literature databases published between 2005 and 1 January 2016 were searched using 3 key search phrases. Papers were included if the study investigated patient dissatisfaction in primary unilateral or bilateral TKA. Information from each article was categorized to the domains of socioeconomic, preoperative, intraoperative, and postoperative factors affecting patient dissatisfaction. RESULTS: This review found that patient dissatisfaction pertains to several key factors. Patient expectations prior to surgery, the degree of improvement in knee function, and pain relief following surgery were commonly cited in the literature. Fewer associations were found in the socioeconomic and surgical domains. CONCLUSION: Identifying who may be dissatisfied after their TKA is mystifying; however, we note several strategies that target factors whereby an association exists. Further research is needed to better quantify dissatisfaction, so that the causal links underpinning dissatisfaction can be more fully appreciated and strategies employed to target them.

Impact of Raised Serum Cobalt Levels From Recalled Articular Surface Replacement Hip Prostheses on the Visual Pathway.

BACKGROUND: The articular surface replacement (ASR) was recalled in 2010 because of higher than expected revision rates. Patients reported symptoms of neurologic dysfunction including poor vision. This cohort study, using objective measurements, aimed to establish whether a higher incidence of visual function defects exists in ASR patients. METHODS: Thirty-three ASR patients and 33 non-ASR controls (control 1) were recruited. Data were compared with normative population data from the visual electrophysiology database (control 2). Patients underwent investigations for serum cobalt levels, psychophysical visual tests, and extensive electrophysiological visual testing. RESULTS: After excluding 2 subjects with pre-existing eye disease, data from 33 ASR patients were compared with the 2 control cohorts. The median serum cobalt level in the ASR group (median, 52 nmol/L [interquartile range, 14-151 nmol/L]) was significantly higher than that in the control 1 cohort (median, 7 nmol/L [interquartile range, 5-14 nmol/L]; P < .0001). The photoreceptor function of patients with an ASR of the hip showed significantly larger electroretinography mixed rod-cone b-wave amplitudes than both control 1 and control 2 cohorts (P = .0294 and .0410, respectively). Abnormalities in macular function as reflected by multifocal and scotopic electroretinography were more prevalent in control 1 (P = .0445 and .0275, respectively). Optic nerve pathway measurements using visual-evoked potential latency was significantly longer in the ASR group compared with those in the control 2 cohort (P = .0201). There were no statistical differences in visual acuity. CONCLUSION: A statistically significant disturbance in visual electrophysiology was found in the ASR group when compared with the control groups. These differences did not translate to identifiable clinical visual deficits. Orthopedic surgeons need to be aware of the possibility of visual dysfunction in patients with ASR and other metal-on-metal hip arthroplasties; however, routine visual testing is not recommended.

Tibial Tubercle Osteotomy in Revision Knee Arthroplasty.

BACKGROUND: Obtaining adequate exposure while maintaining the integrity of the extensor mechanism is crucial to the success of revision knee arthroplasty. This is particularly important in infected cases where staged procedures are necessary. While the use of a long, tibial tubercle osteotomy (TTO) is an established method to improve exposure, controversy still exists concerning complication rates and sequential use. METHODS: Forty-two TTOs were performed in revision knee arthroplasties between 2009 and 2015. Follow-up period ranged from 3 to 24 months. Twenty-four TTOs were performed for single-stage revisions, and 18 TTOs were performed for 2-stage infected revisions. In infected cases, the initial osteotomy was left unfixed between stages. Screws were used to fix the osteotomy flap in all cases. RESULTS: All osteotomies united with no fractures, and there were no extensor lags. Minor proximal migration was noted in 1 case, and refixation was required in another. Greater range of motion (ROM) and improved Oxford Knee Scores were achieved in the single-stage revision group. In the infected 2-stage group, sequential use did not decrease union rates, and infection was eradicated in 14 of the 16 knees (88%). CONCLUSION: We conclude that TTO is a safe and reproducible procedure when exposure needs improving in revision knee arthroplasty. In 2-stage revisions, sequential osteotomies do not decrease union rates, and leaving the osteotomy unfixed after the first stage does not cause any adverse issues.

Patient-specific instrumentation does not improve radiographic alignment or clinical outcomes after total knee arthroplasty.

Background and purpose - Patient-specific instrumentation (PSI) for total knee arthroplasty (TKA) has been introduced to improve alignment and reduce outliers, increase efficiency, and reduce operation time. In order to improve our understanding of the outcomes of patient-specific instrumentation, we conducted a meta-analysis. Patients and methods - We identified randomized and quasi-randomized controlled trials (RCTs) comparing patient-specific and conventional instrumentation in TKA. Weighted mean differences and risk ratios were determined for radiographic accuracy, operation time, hospital stay, blood loss, number of surgical trays required, and patient-reported outcome measures. Results - 21 RCTs involving 1,587 TKAs were included. Patient-specific instrumentation resulted in slightly more accurate hip-knee-ankle axis (0.3°), coronal femoral alignment (0.3°, femoral flexion (0.9°), tibial slope (0.7°), and femoral component rotation (0.5°). The risk ratio of a coronal plane outlier (> 3° deviation of chosen target) for the tibial component was statistically significantly increased in the PSI group (RR =1.64). No significance was found for other radiographic measures. Operation time, blood loss, and transfusion rate were similar. Hospital stay was significantly shortened, by approximately 8 h, and the number of surgical trays used decreased by 4 in the PSI group. Knee Society scores and Oxford knee scores were similar. Interpretation - Patient-specific instrumentation does not result in clinically meaningful improvement in alignment, fewer outliers, or better early patient-reported outcome measures. Efficiency is improved by reducing the number of trays used, but PSI does not reduce operation time.

Prosthetic alignment after total knee replacement is not associated with dissatisfaction or change in Oxford Knee Score: A multivariable regression analysis.

BACKGROUND: Approximately 18% of the patients are dissatisfied with the result of total knee replacement. However, the relation between dissatisfaction and prosthetic alignment has not been investigated before. METHODS: We retrospectively analysed prospectively gathered data of all patients who had a primary TKR, preoperative and one-year postoperative Oxford Knee Scores (OKS) and postoperative computed tomography (CT). The CT protocol measures hip-knee-ankle (HKA) angle, and coronal, sagittal and axial component alignment. Satisfaction was defined using a five-item Likert scale. We dichotomised dissatisfaction by combining '(very) dissatisfied' and 'neutral/not sure'. Associations with dissatisfaction and change in OKS were calculated using multivariable logistic and linear regression models. RESULTS: 230 TKRs were implanted in 105 men and 106 women. At one year, 12% were (very) dissatisfied and 10% neutral. Coronal alignment of the femoral component was 0.5 degrees more accurate in patients who were satisfied at one year. The other alignment measurements were not different between satisfied and dissatisfied patients. All radiographic measurements had a P-value>0.10 on univariate analyses. At one year, dissatisfaction was associated with the three-months OKS. Change in OKS was associated with three-months OKS, preoperative physical SF-12, preoperative pain and cruciate retaining design. DISCUSSION: Neither mechanical axis, nor component alignment, is associated with dissatisfaction at one year following TKR. Patients get the best outcome when pain reduction and function improvement are optimal during the first three months and when the indication to embark on surgery is based on physical limitations rather than on a high pain score. LEVEL OF EVIDENCE: 2.

Bilateral prosthetic hip joint infections associated with a Psoas abscess. A Case Report.

INTRODUCTION: Psoas abscess is a recognized but under-diagnosed complication of prosthetic hip joint infections. CASE REPORT: We report a case of a 68-year-old man with right and left hip arthroplasties performed 22 and 14 years ago, respectively, who presented with non-specific symptoms and was subsequently diagnosed with left psoas abscess on CT scan. Drainage of the psoas abscess was complicated by the formation of a discharging sinus connected to the left hip. He then developed an infected right thigh haematoma, which also formed a discharging sinus connecting to the right hip post-drainage. He was treated with bilateral two-stage revision total hip arthroplasties and multiple courses of prolonged antibacterial therapy. Both abscesses and hip joints cultured the same species of multi-sensitive Staphylococcus aureus. The causal link between the psoas abscess and the prosthetic hip infections is discussed, as well as the investigation and management. CONCLUSION: We recommend routine exploration of the iliopsoas bursa when revision of an infected total hip arthroplasty is performed to rule out intrapelvic spread of the infection [3]. There should be high index of suspicion of prosthetic hip infection in patients presenting with Psoas abscess and vice versa. A CT scan might be warranted to rule out concomitant infection in both these patients.

Cluster hole versus solid cup in total hip arthroplasty: a randomized control trial.

Acetabular osteolysis has been linked to polyethylene debris that is generated in the hip migrating through screw holes in the acetabular component. Solid-backed acetabular components were designed to decrease this osteolysis. This prospective trial randomized 100 patients undergoing total hip arthroplasty to either a solid-backed or a cluster-hole acetabular component-all without screws. At 5years post-surgery, 34.4% of all patients had osteolytic lesions that were visible on CT. There was no significant difference in either presence or volume of the osteolytic lesions, cup migration or functional outcomes (OHS) between the groups. There may no longer be a detriment to using cluster-hole cups instead of solid cups in all hips. This would then give the surgeon the option to use screws for stability as required.