Efficacy of Intrawound Vancomycin in Prevention of Periprosthetic Joint Infection After Primary Total Knee Arthroplasty: A Prospective Double-Blinded Randomized Control Trial.

BACKGROUND: Periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is a devastating complication. Intrawound vancomycin powder has been shown to reduce infection rates in spine surgery, but its role in arthroplasty remains controversial. This prospective randomized control trial aimed to evaluate the efficacy of intrawound vancomycin in preventing PJI after primary TKA. METHODS: A total of 1,022 patients were randomized to the study group (n = 507, who received 2 grams intrawound vancomycin powder before arthrotomy closure) or to the control group (n = 515, no local vancomycin) with a minimum follow-up of 12-months. The primary outcome was the incidence of PJI or surgical site infection (SSI). Secondary outcomes included associated minor complications such as stitch abscess, persistent wound drainage, and delayed stitch removal. Other parameters evaluated include reoperation rates and incidences of nephrotoxicity. RESULTS: The overall infection rate in 1,022 patients was 0.66%. There was no significant difference in PJI rate in the study group (N = 1; 0.2%) versus the control group (N = 3; 0.58%), P = .264. Reoperation rates in the study group (N = 4; 0.78%) and control (N = 5; 0.97%), and SSI rates in the study (N = 1; 0.2%) and control groups (N = 2; 0.38%) were comparable. The Vancomycin cohort, however, demonstrated a significantly higher number of minor wound complications (n = 67; 13.2%) compared to the control group (n = 39; 7.56%, P < .05). Subgroup analysis showed diabetics in the study group to also have a higher incidence of minor wound complications (24 [14.1%] versus 10 [6.2%]; P < 05]. Multivariate analyses found that vancomycin use (odds ratio = 1.64) and smoking (odds ratio = 1.85) were associated with an increased risk of developing minor wound complications. No cases of nephrotoxicity were reported. CONCLUSIONS: Intrawound vancomycin powder does not appear to reduce PJI/SSI rate in primary total knee arthroplasties, including high-risk groups. Although safe from a renal perspective, intrawound vancomycin was associated with an increase in postoperative aseptic wound complications. Intrawound vancomycin may not be effective in reducing the rate of PJI in primary TKA.

Improved intra-operative decision making in RA-TKR with the help of pre-operative CT scan.

Background: Robotic-assisted total knee replacement (RA-TKR) is a significant advancement in orthopedic surgery, but intra-operative decision-making remains challenging. Pre-operative imaging techniques, particularly CT scans, have gained momentum, providing insights into the patient's anatomy, improving implant positioning and alignment. However, further research is needed to explore their influence on RA-TKR planning and execution. Materials and methods: The hospital based cross-sectional study was conducted in Orthopedics department of Sparsh Speciality Hospital, Bangalore & Sunshine Hospital, Hyderabad. A total of 1020 participants in the age group over 50 years during the study period were included based on convenient sampling. The axial CT images were taken preoperatively and RA-TKA was done for all the patients. Results: The study participant's average age was 64.01 ± 7.13. Out of 1020 patients 259 (24.4%) were males and 761 (74.6%) were females. The median femoral, tibia and Polyethylene predicted and the actual component were same with the side of surgery and BMI. The median femoral predicted actual component was significantly higher among the age category of more than 80 years when compared to other age groups. The median femoral, tibia and Polyethylene predicted was higher in males when compared to females. Conclusion: Pre-operative CT scans enhance RA-TKR procedures by providing precise anatomical insights, enhancing implant placement, and identifying potential issues, improving surgical outcomes and patient satisfaction.

Patellar Dislocation Masking a Tibial Post Fracture: An Unusual Complication of Posterior Stabilized Total Knee Arthroplasty.

Posterior stabilized total knee arthroplasty (TKA) has established itself as a highly effective design for total knee arthroplasty, renowned for its longevity and success. However, a subset of cases, approximately 6-12%, faces early failure, necessitating revision procedures. This case report presents a unique and previously undocumented complication involving a tibial post fracture following hyperflexion of the knee, masked by chronic patellar dislocation. This case highlights the importance of considering polyethylene wear-related failure in cases of instability without an apparent history of trauma. The surgical intervention involved polyethylene insert exchange, patellar debulking, lateral retinacular release, and quadriceps tendon double-breasting.

Relationship between femoral component placement and patient-specific anatomical rotational landmarks in robotic arm assisted total knee Arthroplasty- a multicentric study.

Introduction: Osteoarthritis of the knee is a common problem in the elderly, leading to severe morbidity. Total Knee Arthroplasty (TKA) is a widely validated surgery to provide a remarkable extent of knee function and simultaneously alleviates pain for knee osteoarthritis (OA). It is clearly understood that precision of the rotational alignment and accuracy of the technique in the placement of the femoral component is a prerequisite for excellent and successful outcomes of TKA. Advanced technology has now allowed surgeons to understand patient-specific variabilities in anatomical reference landmarks and the relationship of component positioning in relation to the reference landmarks to achieve accurate gap balancing with minimal soft tissue release.14 Robotic Arm Assisted-Total Knee Arthroplasty (RAA-TKA) is a semi-automated system that enables us in replicating the same. Using this technology, the bony resections, component positions, probable component sizing and gap balancing can be tentatively planned preoperatively with CT Scan Analysis and executed intraoperatively. Hence this study was undertaken to estimate the relationship between femoral component placement to normal rotational landmarks such as the Posterior Condylar Axis (PCA) and to quantitatively evaluate coronal and sagittal plane correction obtained. Also, we aimed to use the data to detect any anatomical variations in the study population and evaluate the accuracy of predicted component sizing, including gender-based evaluation. Materials and methods: A Prospective Observational Study of 1073 knees of patients of either sex above 50 years of age with Kellgren Lawrence Grade 4 Osteoarthritis of the knee which were confirmed with X-Ray undergoing RAA-TKA using MAKO Robotic System using Stryker Triathlon (Cruciate Substituting) CS Knee was conducted during the period between 2022 and 2023 in two South Indian hospitals specializing in joint replacement surgeries. Results: We found a statistically significant difference between the native Posterior Condylar Axis (PCA) (4.82 ± 2.15°) and final femoral component external rotation (3.24 ± 1.29°) with a p-value of <0.001 at 95% confidence interval. The accuracy of component size prediction was 99.8%. Also, analysis in our study has shown the most common implant sizes to be 4 in males and 2 in females. We also found no statistically significant difference based on age, size, laterality, or primary varus deformity. Conclusions: RAA-TKA provides patient-specific alignment/restricted kinematic alignment which might further enhance the outcome for the patient. Reliable deformity correction in coronal and sagittal planes can be achieved. Accurate flexion and extension gap balancing can be done through component placement and with minimal soft tissue dissection. Irrespective of all the advantages noted in RAA-TKA, further follow-up and long-term outcome studies are required to properly gauge and analyze this new technology.

Unveiling Scapular Pseudo-winging: A Case Report on Ventral Osteochondroma of the Scapula in a 21-year-old.

Introduction: Scapular pseudo-winging caused by ventral osteochondromas is a rare condition that has been reported in only a handful of cases. This case report describes a 21-year-old male patient with scapular pseudo-winging due to ventral osteochondromas of the scapula. This report adds to the limited literature on this topic and highlights the importance of considering ventral osteochondromas as a possible cause of scapular pseudo-winging. Case Report: A 21-year-old male presented with a swelling on his left upper back that had gradually increased in size over the past 10 years. Physical examination revealed a bony hard swelling arising from the medial border of the scapula, with associated scapular pseudo-winging. Diagnostic imaging confirmed the presence of two ventral osteochondromas located on the body of the scapula. Surgical excision was performed to address the patient's cosmetic concerns. Conclusion: This case report highlights the importance of considering ventral osteochondromas as a possible cause of scapular pseudo-winging. It contributes to the existing literature by documenting a rare presentation and providing insights into the clinical course, diagnostic imaging, and surgical management of this condition. By raising awareness among tumor surgeons and orthopedic surgeons, this report may aid in early recognition and appropriate management of scapular pseudo-winging cases caused by ventral osteochondromas. Furthermore, this report expands our understanding of the etiology and treatment options for scapular pseudo-winging, potentially benefiting patients across various clinical specialties. Categories: Oncology, orthopedics.

Corrigendum to "Relative frequency of avascular necrosis of the hip as indication for primary Total Hip Arthroplasty in the USA vs. India" [J. Orthop. 36C (2023) 1-6].

[This corrects the article DOI: 10.1016/j.jor.2022.12.002.].

Patella non-resurfacing in primary total knee arthroplasty provides good functional results-a retrospective review of nine thousand three hundred forty six knees.

PURPOSE: Patellar resurfacing has long been a contentious subject in TKA with no consensus and the literature yielding disparate results. The aim of this study was to evaluate the long-term functional outcomes and complications of patients undergoing primary TKA without patellar resurfacing (non-resurfacing). METHODS: This study retrospectively analysed 9346 patients who underwent primary manual jig-based TKA without patellar resurfacing at a single high-volume arthroplasty centre between 2010 and 2018. Patients with a minimum three year follow-up irrespective of disease etiology and implant manufacturer were included in the study. Primary outcome was measured using Oxford knee score and patellofemoral Feller score. Secondary outcomes included determining the incidence of patellofemoral complications and re-operation rates following TKA. RESULTS: A total of 8695 knees were eligible for final evaluation having a mean follow-up of 6.6 years. Mean age of the patients was 62.6 (SD-7.5) years with female predominance of (N-6619, 70.8%). The majority of the patients had primary OA (N-8792, 94.1%) with varus deformity (N-8642, 92.46%). Depuy was the most used manufacturer (n = 2592, 26.4%) with the posterior stabilised (N-4127, 44.2%) design being the most predominant. The mean Feller score of the study population was 24.5 (SD = 3) with a majority of patients having good to excellent outcomes (86.95%, N-8424) and mean Oxford knee score was 36.9 (SD-6.9) with a majority of the patients having an OKS greater than 30 (87.1%, N-8133) with anterior knee pain (AKP) reported in only 4.8% patients (N-418). Most common complications included patellar clunk (N-56, 0.7%), traumatic patellar fractures (N-62, 0.8%), quadriceps tendon tear (N-54, 0.7%) and patellar dislocation (N-4, 0.05%) CONCLUSION: Patellar non-resurfacing has no detrimental impact on functional outcomes and incidence of AKP. We conclude that it is a safe, cost-effective and satisfactory approach in primary TKA with no significant complications.

Partial versus total knee arthroplasty for isolated antero-medial osteoarthritis - An analysis of PROMs and satisfaction.

AIM: This study aimed to compare the patient-reported functional outcomes and patient satisfaction after medial Unicompartmental Knee Arthroplasty (UKA) versus Total Knee Arthroplasty (TKA), performed for anteromedial osteoarthritis (AMOA) of the knee in patients from an Indian population, at a minimum 3-year follow-up. METHODS: This is a prospective matched cohort study (1:2 ratio). One hundred and one UKA cases were matched to 206 TKA cases by propensity score matching for age, body mass index (BMI), gender distribution, and the Charlson Comorbidity Index (CCI). The primary outcome (Oxford knee score, OKS) was assessed at a 3-year follow-up, along with secondary outcomes (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] Score, Forgotten Joint Score (FJS), Anterior Knee Pain (Kujala) score, patient satisfaction, and revision rate at the final follow-up). RESULTS: The UKA group was superior to the TKA group in patient-reported functional outcomes based on the OKS (p = 0.004). Using the FJS score, UKA was more likely to be a forgotten joint compared to TKA (p < 0.001). However, differences in the OKS and FJS did not meet the reported minimal clinically important difference (MCID) thresholds. Quality of life (EuroQol-5D VAS scale) was found to be significantly higher in the UKA group (p < 0.001). Patients in the UKA group were more likely to be very satisfied (75.2%) versus the TKA group (62.1%, p = 0.023). CONCLUSION: For AMOA, UKA was associated with improved patient satisfaction compared to TKA. Although patient-reported outcome measures were statistically in favour of UKA over TKA, the differences were not clinically significant. Multicenter and randomized studies comparing the two procedures are warranted. EVIDENCE: Level-II Therapeutic.

Relative frequency of avascular necrosis of the hip as indication for primary Total Hip Arthroplasty in the USA vs. India.

Introduction: Background: Primary total hip arthroplasty (THA) is performed for a variety of pathologies. Osteoarthritis (OA) is the most common indication for THA in the United States of America (USA). The study aims to establish the incidence of indications for THA in the USA as compared to India and to assess whether Avascular Necrosis (AVN) of the Hip is a more frequent indication for THA in India than in the USA. Methods: The National Inpatient Sample database (USA) and two Indian databases (one national and one regional) were analyzed to identify all patients who underwent primary THA within the databases. The relative frequencies of each indication for THA were determined. The patients' demographics and risk factors for AVN of the hip were recorded and assessed. The data were then compared across the patients in the USA and the patients in India. Results: 225,061 primary THA patients were identified in the USA database and 20,288 in the Indian database. The proportion of primary THA performed for AVN in the American database (5.97%) was significantly lower than the proportion of THA performed for AVN in the Indian database (51.8%). Conclusion: The relative frequency of AVN as an indication for THA is significantly higher in India than in the USA. It is important to recognize the differences in relative indications for THA between world populations, as outcomes after THA among Eastern populations of the world may not be equivalent to ones seen in their Western counterparts.

High Prevalence of Isolated Antero-medial Osteoarthritis (AMOA) in Indian Patients Undergoing Primary Total Knee Arthroplasty.

Background: Isolated antero-medial osteoarthritis (AMOA) of the knee is a distinct pattern of arthritis. Medial arthritis of the knee in select patients can be managed with uni-compartmental arthroplasty (UKA), with studies showing shorter hospital stay, faster rehabilitation and reduced medical complications in the post-operative period compared to TKA. However, the prevalence of AMOA in Indian patients with osteoarthritis of the knee is unknown. The aim of this study was to evaluate the prevalence of AMOA in patients undergoing primary TKA for OA. Methods: This was a prospective evaluation of 2518 knees in 1936 patients who were selected for primary TKA. Pre-operative radiographs were screened based on the Oxford UKA Radiological decision aid and diagnosis of AMOA was established. All 2518 knees underwent primary total knee arthroplasty and cases of AMOA were confirmed intra-operatively based on ACL integrity, lateral compartment wear and medial compartment wear pattern. Cases with AMOA arthritic wear pattern were considered amenable for UKA if radiographs showed intact lateral joint space, intra-operatively those with intact and functional ACL, acceptable patellofemoral wear (Outerbridge I-II). Results: We report a prevalence of 46.94% of AMOA, who were amenable for UKA. Obese patients were more likely to have a damaged or non-functional ACL and more likely to have a high degree of wear, not amenable for UKA (p < 0.05). Non-functional ACL was associated with higher prevalence of posterior extension of arthritic wear. Conclusion: This study demonstrated a high prevalence (46.94%) of antero-medial osteoarthritis (AMOA), amenable for UKA. Patient selection is important for improving outcomes after TKA or UKA. Future studies are warranted to compare outcomes of both UKA and TKA in patients with isolated AMOA of the knee.

Comparison of patient reported outcomes after robotic versus manual total knee arthroplasty in the same patient undergoing staged bilateral knee arthroplasty.

Background: Robotic-assisted total knee arthroplasty (RATKA) has been proven to improve accuracy of component positioning and reducing alignment target outliers. However, the clinical benefit of robotics is often debated. Recent studies have shown reduced pain and faster recovery in the immediate post-operative period and may be associated with improved PROMs and satisfaction. The aim of this study was to assess PROMs and satisfaction in a unique patient population undergoing bilateral staged TKA to compare manual (MTKA) and RATKA in the same patient. Methods: 55 patients underwent bilateral staged TKA, performed by a single surgeon at a single institute. Patients who underwent TKA for the first knee with manual technique and RATKA for the second side, were eligible for inclusion in the study. Primary outcome assessed was the Oxford Knee Score and secondary outcomes included the Forgotten Joint Score (FJS), patient satisfaction, mean duration for independent ambulation after TKA, and patient perspectives on recovery evaluated with a questionnaire. Results: Both RATKA and MTKA were associated with comparable PROMs. Though RATKA was associated with improved joint perception (Mean FJS after MTKA surgery was 70.3 (SD = 10.66) and significantly lower than the mean FJS after RATKA (73, SD = 10.95, p-value < 0.01), but the difference was not clinically relevant. A higher proportion of patients were more likely to be very satisfied or satisfied after RATKA. A significant proportion of patients felt the knee operated with RATKA was less painful and felt more natural compared to MTKA at final follow-up (p < 0.01). Majority of patients would undergo RATKA again and recommend robotic-TKA to others. Conclusion: Robotic-assisted surgery was associated with improved patient satisfaction, faster independent ambulation compared to manual techniques. PROMs however, were comparable without clinically significant differences. Patients preferred robotic-assisted surgery, with a significantly higher proportion perceiving knee operated by RATKA felt more natural.

Pre-operative planning and templating with 3-D printed models for complex primary and revision total hip arthroplasty.

Background: Complex primary and revision THR requires comprehensive understanding of abnormal bony anatomy. Evaluation and classification of acetabular bone defects is essential to manage them appropriately. It is difficult to appreciate complex defects using conventional 2-Dimensional radiological modalities. 3D printed models can provide both visual and tactile reproduction of the bony anatomy, with potential for better pre-operative planning and making these complex surgeries more precise and accurate. Materials and methods: Anatomical 3D models of pelvis and femur were made based on CT scans of 27 patients undergoing complex primary THR/Revision THR by FDM (Fusion Deposition Modeling) technology using Flash Forge-Dreamer 3D printer with ABS (plastic) material. Models were used for pre-operative planning and simulation of surgery. Aims of the study were to study the accuracy of 3D models in predicting the implant sizes, accuracy in evaluation of acetabular bone defects and validating the utility of 3 D models through surgeon feedback. Results: The acetabular cup size and placement was accurate in 25 (92.6%) patients. Preoperative acetabular bone defect was accurately estimated in all the patients. There were no neurovascular complications at early and 1-year follow-up in this case series. Model realism and reliability survey response from five surgeons was graded, with average overall usefulness of 3D models of 4.86/5, average model realism was 4.9/5, average usefulness for planning was 4.74/5 and usefulness for teaching was 5/5. Conclusion: 3D models are accurate and help in assessing acetabular bone deficiencies reliably in complex and revision THR. Anatomical models help in surgical planning and simulation, enabling surgeons in predicting the correct implant sizes and importantly placement of acetabular cup and for management of bone defects. The safe trajectory of acetabular screws can be simulated and determined, thereby avoiding penetration into pelvis and neuro-vascular injuries.

Influence of vitamin D levels on outcomes and nosocomial COVID-19 infection in patients undergoing total knee arthroplasty- a cohort study.

Purpose: This study aimed to audit the effects of vitamin D3 on the early functional outcomes, the incidence of nosocomial COVID-19 infection and complications in patients undergoing elective Total Knee Arthroplasty (TKA). Methods: This was a retrospective study involving patients undergoing primary unilateral TKA between January 2020 to May 2021 operated by a single surgeon using a single implant. Participants were divided into two cohorts, Deficient-vitamin D3 level <20 ng/ml and Sufficient-vitamin D3 level ≥20 ng/ml. Assessment for Knee Society Score and Oxford Knee Score (OKS) was done preoperatively and one year after TKA. Nosocomial COVID-19 infection rate, 30-day re-admissions and complications were noted during the study. Results: 235 patients were divided into 2 cohorts matched by age, gender and ASA grades. 74 patients belonged to the deficient group and 161 belonged to the sufficient group. The mean preoperative scores in the sufficient group were higher than the deficient group (OKS = 15.74 vs 12.95; KSS = 88.91vs 85.62). Similarly, the one-year postoperative scores in the sufficient group were significantly higher (OKS = 36.54 vs 35.16; KSS = 164.01 vs 161.22). A linear correlation was present between preoperative score (r = 0.273) & post-operative scores (r = 0.141) with serum vitamin D3 levels. Vitamin D3 deficient individuals had higher nosocomial COVID-19 infection rate (10.81% vs 4.96%,p = 0.16). The incidence of complications like DVT, embolism, stroke, infection and fracture were not statistically different in the two groups. Conclusion: Vitamin D positively influences the outcomes of TKA and protects against nosocomial COVID-19 infection in patients undergoing elective TKA.

Enhanced Mid-Resection Workflow Technique for Severe Varus Deformity Correction Using Robotic-Arm Assisted Total Knee Arthroplasty.

INTRODUCTION: Robotic technology in total knee arthroplasty has been proven to improve accuracy of component positioning, achieve alignment targets, and balance the knee objectively. However, the utility of robotics in correction of severe varus deformities of the knee has not been investigated in detail. The aim of this paper was to establish the utility and describe the technique of robotic-arm assisted total knee arthroplasty (RA-TKA) in achieving pre-balance in severe varus deformities of the knee. MATERIALS AND METHODS: Among the existing Mako (Stryker, Kalamazoo, Michigan) RA-TKA workflows, pre-resection workflow is limited to knees which can be pre-balanced by component positioning according to functional alignment. Mid-resection workflow (distal femur/tibia first) is reserved for complex cases, whereby the extension gap is balanced first. In our experience, both workflows could not achieve pre-balance in severe varus deformities, necessitating the need to develop a novel technique. The ability of the robot to execute precise bone cuts allows for a provisional postero-medial femoral bone cut in flexion, giving access to remove large inaccessible posterior osteophytes and the tight posterior capsule, thus balancing the knee in extension. The flexion gap is subsequently matched to the extension gap by alterations in axial component positioning. CONCLUSION: This novel "enhanced mid-resection workflow" technique establishes the utility of the RA-TKA in balancing severe varus deformities of the knee. We also propose an algorithm which simplifies and helps surgeons choose between the three workflows to pre-balance knees irrespective of the severity of the varus deformity.

Two-Staged Total Knee Arthroplasty in Juvenile Rheumatoid Arthritis with Severe Flexion Deformity: A Case Report.

CASE: Juvenile rheumatoid arthritis (JRA) is associated with severe flexion contracture of the knees disabling a patient's ability to walk. Although various treatment modalities are available in the literature, we report a 2-stage procedure in a case of a 22-year-old female JRA patient with bilateral severe flexion deformity of the knee: stage 1-correction of the flexion contracture deformity by ring fixators and stage 2-total knee arthroplasty (TKA) for arthritis. To the best of our knowledge, no such approach has been reported previously. CONCLUSIONS: An Ilizarov ring fixator is a safe technique for gradual correction of a severe flexion deformity. Subsequent TKA can be performed as a standard procedure.

Avoiding Lateral Laxity in Robotic Arm-Assisted Total Knee Arthroplasty-A Surgical Technique Describing a New Method of Gap Capture and Balancing Strategy.

INTRODUCTION: Optimal flexion-extension gap balancing is an important factor in outcomes after total knee arthroplasty. Knees with varus deformities are commonly associated with a greater degree of lateral laxity both in extension and flexion. Residual lateral laxity could be encountered by surgeons during component trialling after robotic-assisted total knee arthroplasty (RATKA), necessitating additional medial soft tissue release for a thicker insert. This study describes a new technique of gap assessment during RATKA and we propose a functional alignment based balancing strategy to avoid residual lateral laxity. MATERIALS AND METHODS: This surgical technique was prospectively employed in 105 patients undergoing primary MAKO® (Stryker, Kalamazoo, Michigan) RATKA for osteoarthritis of the knee with varus deformity, between January 2021 and July 2021. Patients included had an initial lateral extension laxity of more than 24mm. Surgical data points collected consisted of characterization of the laxity profile of the knee using the medial and lateral extension and flexion initial gap captures, final gap captures after dynamic balancing with a functional alignment strategy, and residual lateral extension gap laxity in millimeters at the end of implantation. RESULTS: The mean initial lateral extension gap was 25.76mm (standard deviation [SD]=1.47) and the mean lateral flexion gap was 24.4mm (SD=1.94). Balance was achieved in all the patients with a 9 or 11mm insert, with a mean residual lateral laxity of 0.51mm (SD=0.73, range 0-2mm). The majority of patients (n=66, 62.85%) had zero lateral laxity at the end of final implantation while 24 patients (22.8%) had 1mm of residual lateral laxity. CONCLUSION: Residual lateral joint laxity can be avoided consistently and predictably in RATKA cases with initial gap capture of up to 30mm in lateral extension and flexion with this new technique of gap capture and employing various steps of balancing strategy described.

An Incognizant Glitch-pinnacle Polyliner Dissociation: A Case Report.

Introduction: Liner dissociation of the pinnacle total hip arthroplasty system is a rare but documented complication. Although a few reports are published internationally, to the best of our knowledge no cases have been documented from India so far. Case Report: A 31-year-old male presented with failed femoral head fracture fixation for which total hip replacement was done. Postoperatively at 18 months, he was diagnosed with pinnacle liner dissociation and liner exchange was performed. Conclusion: This report aims to raise awareness about the incidence of pinnacle liner dissociation.

When can I go home after my knee replacement? Factors affecting the duration of in-hospital stay after knee replacement.

BACKGROUND: Despite a sevenfold decline in the number of postoperative nights (21-3) after a total knee arthroplasty (TKA) over the last four decades, predictors of length of stay (LOS) are not fully understood. We attempted to ascertain these factors by analyzing a large cohort of patients. METHODS: Prospectively collected data between January 2016 and March 2017 were retrospectively analyzed at our institute. Charts of 1663 consecutive, simple primary unilateral and bilateral TKAs were reviewed for the LOS excluding staggered bilateral, complex primary and revision knees. STATISTICAL ANALYSIS: Preoperative variables [demographics, cash/credit status, historical, clinical, laboratory findings, Knee Society Function Scores and Oxford Knee Scores (OKSs)] were scrutinized by multivariate regression to identify significant factors affecting LOS and formulate model equations for patients and health caregivers. Results were incorporated into an iOS application, which was tested for accuracy. RESULTS: Among 1524 unilateral and 139 bilateral TKAs, mean LOS was 4.4 and 5.2 days, respectively. Five factors, namely insurance, flexion/hyperextension deformity, preoperative OKS and a rheumatoid etiology, were significantly associated with prolonged LOS in unilateral knees. The impact of these independent variables on LOS could be calculated by: [Formula: see text]For bilateral cases, the only significant variable extending LOS was a low preoperative OKS and the equation is given as follows: [Formula: see text]The iOS-app-predicted LOS and actual LOS were similar (p > 0.05) for 115 prospectively operated knees. CONCLUSION: Poor preoperative OKS, rheumatoid etiology, flexion and hyperextension deformity and delays in insurance affected unilateral TKR LOS, while poor preoperative OKS alone affected LOS in bilateral cases.