Who Are the Anatomic Outliers Undergoing Total Knee Arthroplasty? A Computed Tomography-Based Analysis of the Hip-Knee-Ankle Axis Across 1,352 Preoperative Computed Tomographies Using a Deep Learning and Computer Vision-Based Pipeline.

BACKGROUND: Dissatisfaction after total knee arthroplasty (TKA) ranges from 15 to 30%. While patient selection may be partially responsible, morphological and reconstructive challenges may be determinants. Preoperative computed tomography (CT) scans for TKA planning allow us to evaluate the hip-knee-ankle axis and establish a baseline phenotypic distribution across anatomic parameters. The purpose of this cross-sectional analysis was to establish the distributions of 27 parameters in a pre-TKA cohort and perform threshold analysis to identify anatomic outliers. METHODS: There were 1,352 pre-TKA CTs that were processed. A 2-step deep learning pipeline of classification and segmentation models identified landmark images and then generated contour representations. We used an open-source computer vision library to compute measurements for 27 anatomic metrics along the hip-knee axis. Normative distribution plots were established, and thresholds for the 15th percentile at both extremes were calculated. Metrics falling outside the central 70th percentile were considered outlier indices. A threshold analysis of outlier indices against the proportion of the cohort was performed. RESULTS: Significant variation exists in pre-TKA anatomy across 27 normally distributed metrics. Threshold analysis revealed a sigmoid function with a critical point at 9 outlier indices, representing 31.2% of subjects as anatomic outliers. Metrics with the greatest variation related to deformity (tibiofemoral angle, medial proximal tibial angle, lateral distal femoral angle), bony size (tibial width, anteroposterior femoral size, femoral head size, medial femoral condyle size), intraoperative landmarks (posterior tibial slope, transepicondylar and posterior condylar axes), and neglected rotational considerations (acetabular and femoral version, femoral torsion). CONCLUSIONS: In the largest non-industry database of pre-TKA CTs using a fully automated 3-stage deep learning and computer vision-based pipeline, marked anatomic variation exists. In the pursuit of understanding the dissatisfaction rate after TKA, acknowledging that 31% of patients represent anatomic outliers may help us better achieve anatomically personalized TKA, with or without adjunctive technology.

Are There More Radiolucent Lines in Patients Who Underwent Total Knee Arthroplasty With or Without a Tourniquet During Cementation at 5 to 8 Years After Surgery?

BACKGROUND: This study investigated the presence and progression of radiolucent lines (RLLs) after cemented total knee arthroplasty (TKA) with or without tourniquet use. METHODS: There were 369 consecutive primary cemented TKAs with 5 to 8 years of follow-up. A tourniquet was used during component cementation in patients who underwent surgery from January 3, 2006, to March 31, 2010. No tourniquet was used from August 14, 2009, to October 14, 2014. There were 192 patients in the tourniquet group (TQ) and 177 patients in the no tourniquet group (NQ). Patient demographics, reoperations, and complications were recorded. RLLs were identified on anteroposterior, lateral, and skyline x-rays at 1, 2, and 5 to 8 years postoperatively using the modern knee society radiographic evaluation system. Demographics, reoperations, complications, and RLLs were compared. Age, sex, and body mass index were similar between groups. Mean tourniquet time in TQ was 11 minutes (range, 8 to 25). RESULTS: The presence of RLLs differed between groups, with 65% of TQ knees having RLLs under any part of the prostheses versus 46% of NQ knees (P < .001). The progression of RLL >2 mm occurred in 26.0% of knees in TQ and 16.7% of knees in NQ (P = .028). There were 13 TKAs that underwent subsequent revision surgery. There was no statistically or clinically significant difference in revision rate between groups (7 revisions in TQ, 6 in NQ, P = .66). CONCLUSION: Less RLLs were identified in NQ versus TQ. There were no statistically or clinically significant differences in revision rates between the NQ and TQ groups at 5 to 8 years.

A Total Knee Arthroplasty Preoperative Optimization Program Managed by an Advanced Practice Provider (Physician Assistant) Decreases Complications and Cost: A Pilot Study.

BACKGROUND: Studies have shown that optimizing modifiable risk factors leads to improved outcomes, with decreased lengths of stay (LOS), readmissions, complications, and hospital costs. Our goal was to demonstrate that use of an advanced practice provider, physician assistant (PA), within an orthopaedic practice would support these outcomes. METHODS: A preoperative optimization program managed by a PA was instituted at an academic medical center. From November 2019 to December 2022, a pilot group of fifteen (15) consecutive primary total knee arthroplasty (TKA) patients who were successfully optimized with the PA-managed program prior to TKA were matched 2:1 to a cohort of thirty (30) TKA patients who did not undergo optimization. Demographics and the modified readmission risk assessment tool score were used to match patients. Variables evaluated included LOS, emergency department visits, and hospital readmissions within 30 and 90 days after surgery, complications, and hospital costs of care. RESULTS: Optimized patients had less complications (P = .004) and significantly shorter (P < .001) mean LOS (1.27 days vs 2.97 days) compared to nonoptimized patients. The difference of hospital cost between cohorts for the primary admission was significant (P = .049). When readmission costs were included, the average hospital cost for the nonoptimized group was significantly higher than the optimized group (P = .018). CONCLUSIONS: Preoperative optimization led by a PA demonstrated significant reductions in LOS and the costs of care between optimized and non-optimized patients, along with decreased complications.

High-Dose Vitamin D Supplementation Can Correct Hypovitaminosis D Prior to Total Knee Arthroplasty.

BACKGROUND: Vitamin D deficiency in the perioperative surgical period is associated with inferior surgical outcomes. There are no established preoperative supplementation regimens in the orthopedic literature. The purpose of this study is to compare the efficacy between 2 different supplementation regimens of vitamin D prior to total knee arthroplasty. METHODS: We conducted a retrospective analysis of 174 patients identified as vitamin D deficient (25(OH)D < 30 ng/mL) who received one of 2 vitamin D supplementation protocols: (1) daily supplementation with D3 on a sliding scale from 1000 to 6000 IU or (2) a loading dose of 50,000 IU D3 weekly for 4 weeks then 2000 IU/d. Serum vitamin D levels were measured at 3 months and 1 month preoperatively. RESULTS: Mean patient age was 65.5(±8.6) years, and 54.6% were female. Deficiency was corrected in 73.3% of patients in the loading dose group and 42.4% of patients in the daily, low-dose group [χ2 (1, N = 174) = 16.53, P < .001]. Patients in the loading dose group also achieved a greater average correction in vitamin D levels. CONCLUSION: This is the first study to compare preoperative vitamin D supplementation protocols. A loading dose regimen of 50,000 IU weekly for 4 weeks followed by a maintenance dose of 2000 IU/d more effectively corrects vitamin D deficiency compared to a low-dose, daily regimen among total knee arthroplasty patients. We recommend this regimen for deficiency correction in patients who have been screened to be deficient in vitamin D preoperatively.

Optimizing Spinal Anesthesia in Same-Day Discharge Knee Arthroplasty Patients: Mepivacaine Versus Ropivacaine.

BACKGROUND: Short-acting spinal anesthetics are playing an increasing role in same-day discharge total joint arthroplasty though their direct comparison remains to be studied. Therefore, this study aims to compare two formulations of spinal anesthesia regarding time to discharge following knee arthroplasty surgery. METHODS: A retrospective study was performed on 207 patients who underwent unicompartmental knee arthroplasty (UKA, n = 172) and total knee arthroplasty (TKA, n = 35) from May 2018 to December 2020 at a single institution and were discharged the same day. Two formulations of the spinal anesthetic were routinely administered in this population: 1) mepivacaine 1.5% 3-4 mL (n = 184) and 2) ropivacaine 0.5% 2.3-2.7 mL (n = 23). Discharge times were subsequently compared between mepivacaine and ropivacaine spinal anesthesia for each surgical procedure and between surgical procedures. RESULTS: There was no significant difference in discharge times between patients receiving mepivacaine versus ropivacaine for UKA (202 minutes [range = 54-449] versus 218 minutes [range = 175-385], P = .45) or TKA (193 minutes [range = 68-384] versus 196 minutes [range = 68-412], P = .93). Similarly, no difference was found in discharge times between UKA and TKA patients receiving mepivacaine (P = .68) or ropivacaine (P = .51). CONCLUSION: There was no significant difference in discharge times between anesthetic agents among knee surgery patients. Therefore, either agent may be recommended for same-day discharge.

Post-Operative Remote Monitoring for Same-Day Discharge Elective Orthopedic Surgery: A Pilot Study.

The purposes of this pilot study are to utilize digital remote monitoring to (a) evaluate the usability and satisfaction of a wireless blood pressure (BP) and heart rate (HR) monitor and (b) determine whether these data can enable safe mobilization at home after same-day discharge (SDD) joint replacement. A population of 23 SDD patients undergoing unicompartmental knee arthroplasty (UKA), total knee arthroplasty (TKA), or total hip arthroplasty (THA) were given a cellular BP/HR monitor, with real-time data capture. Patients took three readings after surgery, observing for specific blood pressure decreases, HR increases, or hypotensive symptoms. If any criteria applied, patients followed a hydration protocol and delayed ambulation. Home coaching was also provided to each patient. Patient experience was surveyed, and responses were assessed using descriptive statistics. Of 18 patients discharged (78%), 17 returned surveys, of which 100% reported successful device operation. The mean "ease of use" rating was 8.9/10; satisfaction with home coaching was 9.7/10; and belief that the protocol improved patient safety was 8.4/10. A total of 27.8% (n = 5) had hypotensive readings and appropriately delayed ambulation. Our pilot findings support the feasibility of and confirm the satisfaction with remote monitoring after SDD arthroplasty. All patients with symptoms of hypotension were successfully remotely managed using a standardized hydration protocol prior to safe mobilization.

Custom total knee: understanding the indication and process.

Patient-specific total knee arthroplasty (TKA) is a copy of the bony knee morphology based on a pre-op computer tomography (CT). The images are segmented in 3D and software is utilized through a proprietary process to generate individual total knee implants to recreate the articulating surfaces. The distal condylar valgus angle of the prosthesis is matched anatomically to the distal femur and reversely matched on the tibia with a thicker lateral insert. The implant, a set of patient-specific jigs (PSJ), which are 3D printed in nylon, and a detailed surgical plan are sent to the hospital in one box. The system is available with one solid or two separated medial and lateral PE inserts. There is a cruciate retaining (CR) and posterior stabilized (PS) version available, including various insert thicknesses. The system allows the addition of two different cemented stem extensions if needed at the time of surgery.

Technology Applications for Arthroplasty: Moving the Field Forward?

Total joint arthroplasty (TJA) is one of the most performed and successful surgeries in the United States for advanced degenerative and inflammatory arthritis with most patients reporting excellent outcomes. However, a large number of patients are still dissatisfied following TJA. To improve outcomes, new technologies such as patient-specific instrumentation and custom implants; smart implant trials; radiologic, computer, and portable accelerometer-based navigation systems; and robotics have been developed. Their overall goals are to avoid the drawbacks of conventional arthroplasty surgery, to simplify the procedures, to improve the accuracy of surgical techniques, to improve outcomes, and to decrease costs. This chapter provides an overview of the current technologies and their applications in TJA.

Translation and Validation of the German New Knee Society Scoring System.

BACKGROUND: In 2011 the Knee Society Score (KSS) was revised to include patient expectations, satisfaction, and physical activities as patient-reported outcomes. Since the new KSS has become a widely used method to evaluate patient status after TKA, we sought to translate and validate it for German-speaking populations. QUESTIONS/PURPOSES: After translation of the new KSS into German using established guidelines, we sought to test the new German version for (1) validity; (2) responsiveness; and (3) reliability. METHODS: The new KSS form was translated and adapted according to the available guidelines. The final version was used to validate the German version of the new KSS (GNKSS) in 133 patients undergoing TKA, of which 100 patients were included in the study as per inclusion criteria. Patients completed the GNKSS form along with the German WOMAC and the German SF-36 scores preoperatively and at the 2-year postoperative followup. Construct validity was tested by comparing domain scores of the GNKSS with domain scores of the German WOMAC and the SF-36. Responsiveness was evaluated by comparing pre- and postoperative scores in all questionnaires in all patients using standardized response means. To evaluate reliability, every second patient (n = 50) in the whole group was asked to complete the GNKSS form a second time 1 week after their 2-year followup; 39 patients responded. This sample group was considered representative after testing the difference among age, sex, body mass index, operation side, preoperative or postoperative GNKSS, and WOMAC scores with the original group. Intraclass correlation coefficients (ICCs) were used to assess reliability and Cronbach's α was an indicator of internal consistency of each domain score. RESULTS: Construct validity was excellent pre- and postoperatively between the GNKSS and the WOMAC for domains including symptoms, satisfaction, total functional score, and total score and activity subdomains, except the expectation domain and advanced and discretionary subdomains of the GNKSS and the stiffness domain of WOMAC. The expectation domain showed either no significant correlation or only weak correlations with the domains of WOMAC pre- as well as postoperatively (r ranging between -0.19 and -0.34). Correlation of the function section of the GNKSS as well as the physical function and role-physical domains of the SF-36 pre- and postoperatively were moderate to strong, respectively, with statistically significant (p < 0.001) r values of 0.49 and 0.48 preoperatively and 0.73 and 0.65 postoperatively. Correlation of the symptom section of the GNKSS and bodily pain domain of the SF-36 was also strong pre- and postoperatively. Regarding responsiveness, all domains of the GNKSS showed large changes except the expectation domain. The symptom and functional sections of the GNKSS showed higher responsiveness than the corresponding pain and function domains of the WOMAC and bodily pain and physical function domains of the SF-36. Also, the total score changes were larger for the GNKSS compared with the WOMAC. No floor or ceiling effect was observed. Reliability was excellent with ICCs of 0.83 to 0.97 as an indicator of test-retest reliability and Cronbach's α values of 0.78 to 0.85 preoperatively and 0.92 to 0.94 postoperatively as an indicator of internal consistency for all domains and subdomains. CONCLUSIONS: The GNKSS is a valid, responsive, reliable, and consistent outcome measurement tool that may be used to evaluate the outcome of TKA. LEVEL OF EVIDENCE: Level II, diagnostic study.

Increased postoperative dexamethasone and gabapentin reduces opioid consumption after total knee arthroplasty.

PURPOSE: Dexamethasone and gabapentin are used in multimodal pain management protocols to reduce postoperative pain after total knee arthroplasty. For both analgesic adjuvants, the optimal dose regimen to reduce opioid usage is still unclear. METHODS: The opioid consumption of patients undergoing primary TKA before and after a change of the analgesic adjuvant medication in our protocol (old protocol: 4 mg of dexamethasone daily for 2 days, 600 mg gabapentin daily for 1 week; new protocol: 10 mg dexamethasone daily for 2 days, 300 mg gabapentin every 8 h for 1 week) were retrospectively compared. All surgeries were performed under spinal anesthesia. Peri- and postoperative pain medication remained unchanged. RESULTS: A total of 186 patients who received TKA between 11/29/2016 and 06/09/2017 were screened. Six patients who received general anesthesia, 4 patients who underwent simultaneous bilateral TKA, and 16 patients with ongoing opioid consumption at the time of surgery were excluded, leaving 80 patients in each group. Opioid consumption within 24 h [morphine equivalents in mg: mean 50.5, standard deviation (SD) 30.0 (old) vs. 39.8, SD 24.2 (new); P = 0.0470], cumulative consumption over 48 h (97.3, SD 64.4 vs. 70.4, SD 51.2; P = 0.0040) and cumulative consumption over 72 h (108.1, SD 79.5 vs. 82.5, SD 72.6; P = 0.0080), were all significantly lower in the new protocol. CONCLUSION: Increased postoperative administration of dexamethasone and gabapentin after TKA is associated with lower opioid consumption. Within the first 48 h, up to about 25% of opioids can be spared, comparing high-dose to low-dose protocols. LEVEL OF EVIDENCE: Therapeutic Level III.

Perioperative Dietary Restriction of Carbohydrates in the Management of Blood Glucose Levels in Patients Undergoing Total Knee Replacement.

BACKGROUND: Approximately 75% of the US population over 65 years has prediabetes or diabetes. Despite current evidence for the efficacy of carbohydrate restriction in managing blood glucose, this practice has not been implemented as part of routine perioperative blood sugar management. We hypothesize that a carbohydrate reduced hospital diet (CRD) of 135 g/d may improve blood sugar levels following total knee arthroplasty (TKA) compared to a non-carbohydrate reduced hospital diet (NCRD). METHODS: We randomized non-insulin-dependent prediabetic and diabetic patients undergoing TKA to either an NCRD or a CRD. Sixty-four patients were enrolled in the study and 2 were excluded, leading to 62 patients in the final analysis. The NCRD group included 14 females (47%) and 16 males (53%), with mean age of 68.5 years (±6.3 years). The CRD group included 16 females (50%) and 16 males (50%), with mean age of 68.0 years (±8.0 years). For hemoglobin A1C, the NCRD group had mean 5.8% (±0.6%) and the CRD group had mean 5.7% (±0.8%). For body mass index, the NCRD group had mean 29.3 kg/m2 (±6.3 kg/m2) and the CRD group 32.7 kg/m2 (±5.0 kg/m2). The primary outcome measure was mean blood glucose. RESULTS: Mean blood sugar values during hospital stay were significantly lower in the CRD group with 121.5 mg/dL (±17.1 mg/dL) compared to the NCRD group 141.2 mg/dL (±31.3 mg/dL, P = .0031). CONCLUSION: Blood sugar levels after surgery can be significantly reduced with a CRD. Further research is necessary to study the effect of reduced blood sugar levels on complications and infection rates following TKA surgery. LEVEL OF EVIDENCE: I.

Optimal Timing of Glucose Measurements After Total Joint Arthroplasty.

BACKGROUND: Postoperative glucose levels after total joint arthroplasty are important to monitor as hyperglycemia has been linked to complications such as periprosthetic joint infection. The purposes of this study were to identify how postoperative glucose values vary during the perioperative period and determine the optimal time to check glucose levels to best evaluate for hyperglycemia. METHODS: A retrospective study was conducted from September 2017 to September 2018 on 314 patients who underwent knee and hip arthroplasties. Blood glucose levels were collected immediately preoperatively, immediately postoperatively, at 5 PM on the day of surgery (DOS), at 9 PM on the DOS, and in the morning of postoperative day (POD) 1. The total number of hyperglycemic patients was assessed at 3 glucose thresholds: strict ≥ 126 mg/dL, intermediate ≥ 137 mg/dL, and lenient ≥ 180 mg/dL. Descriptive statistics were performed for each glucose time period, and adjusted comparisons were made between the mean glucose values and number of hyperglycemic patients at all time points. RESULTS: Mean (±95% confidence interval) glucose values were 105.7 ± 2.1 mg/dL preoperatively, 117.3 ± 2.5 mg/dL immediately postoperatively, 138.6 ± 4.3 mg/dL at 5 PM on the DOS, 142.9 ± 4.3 mg/dL at 9 PM on the DOS, and 116.7 ± 3.1 mg/dL in the morning of POD 1. Values measured at 5 PM and 9 PM were significantly higher than those measured at all other time points in both diabetics and nondiabetics (P < .001 for all). For all 3 hyperglycemia thresholds, the highest number of hyperglycemic patients was observed at 9 PM on the DOS: strict = 205 (65.3%) patients, intermediate = 177 (56.4%) patients; and lenient = 90 (28.7%) patients. CONCLUSION: Most patients who underwent total joint arthroplasty are hyperglycemic postoperatively, and 9 PM on the night of surgery may be the most sensitive time for detecting hyperglycemia in both diabetic and nondiabetic patients, in contrast to traditional POD 1 levels.

Posterior condylar resections in total knee arthroplasty: current standard instruments do not restore femoral condylar anatomy.

INTRODUCTION: Correct femoral rotational alignment in total knee arthroplasty (TKA) is important for femoropatellar knee kinematics as well as for the overall clinical success. The goal of the present study was to evaluate how accurately standard instruments of various manufacturers with specific rotational settings in posterior referencing restore the posterior femoral condylar anatomy and allow a rotational alignment which matches a particular anatomic rotational landmark on CT. METHODS: The anatomical transepicondylar axis (aTEA) and the posterior condylar line (PCL) were identified and the angle formed by these two axes was measured on 100 consecutive CT scans of knees. A virtual posterior condylar resection was performed relative to the aTEA for femoral sizers of various manufacturers in different external rotations ranging from 3° to 7°. The resections of medial and lateral posterior condyle were calculated as well as the condylar twist angle (CTA) between PCL and aTEA. RESULTS: The posterior condylar resection varied between 9 mm and 14 mm on the medial side and between 4 mm and 10.5 mm on the lateral side. The mean CTA was 5.5° of internal rotation (SD ± 1.9°). External femoral rotation resulted in increased resection of the medial posterior condyle and decreased resection of the lateral posterior condyle. CONCLUSION: Femoral sizers using a posterior referencing technique increase, with rising external rotation, medial posterior condylar resection to an extent that may exceed the implant thickness in the majority of systems. Surgeons should be aware that current standard instruments do not restore the anatomy of the posterior medial and lateral condyle and do not align the femoral component parallel to the aTEA, which may result in internal rotation of a symmetric femoral component.

Do modern total knee replacements improve tibial coverage?

PURPOSE: The purpose of the present study is to compare newer designs of various symmetric and asymmetric tibial components and measure tibial bone coverage using the rotational safe zone defined by two commonly utilized anatomic rotational landmarks. METHODS: Computed tomography scans (CT scans) of one hundred consecutive patients scheduled for total knee arthroplasty were obtained pre-operatively. A virtual proximal tibial cut was performed and two commonly used rotational axes were added for each image: the medio-lateral axis (ML-axis) and the medial 1/3 tibial tubercle axis (med-1/3-axis). Different symmetric and asymmetric implant designs were then superimposed in various rotational positions for best cancellous and cortical coverage. The images were imported to a public domain imaging software, and cancellous and cortical bone coverage was computed for each image, with each implant design in various rotational positions. RESULTS: One single implant type could not be identified that provided the best cortical and cancellous coverage of the tibia, irrespective of using the med-1/3-axis or the ML-axis for rotational alignment. However, it could be confirmed that the best bone coverage was dependent on the selected rotational landmark. Furthermore, improved bone coverage was observed when tibial implant positions were optimized between the two rotational axes. CONCLUSIONS: Tibial coverage is similar for symmetric and asymmetric designs, but depends on the rotational landmark for which the implant is designed. The surgeon has the option to improve tibial coverage by optimizing placement between the two anatomic rotational alignment landmarks, the medial 1/3 and the ML-axis. Surgeons should be careful assessing intraoperative rotational tibial placement using the described anatomic rotational landmarks to optimize tibial bony coverage without compromising patella tracking. LEVEL OF EVIDENCE: III.

Improved kinematics of total knee replacement following partially navigated modified gap-balancing technique.

PURPOSE: Navigation-based total knee arthroplasty (TKA) has proven its value for restoration of the limb axis. However, patient-orientated results after TKA show a wide variation from the correct implantation technique. Nonphysiological kinematics without posterior femoral rollback and tibial internal rotation in flexion could be one reason for this. We postulated that a modified gap-balancing technique with navigation of the tibia alone, in comparison to a conventional navigated technique, would: (1) obtain lateral femoral rollback, (2) alter condylar liftoff without midflexion instability, (3) significantly differ in femoral and tibial cuts, (4) not be inferior in leg-axis restoration and (5) be comparable in clinical short-term scores. METHODS: In this prospective study, we compared in vivo navigation-based kinematics pre- and postoperatively of 40 consecutive TKA comprising 21 conventional navigation-based TKA and 19 TKA with the modified gap-balancing technique and a reduced navigation workflow. All cuts were double checked and compared with cuts proposed by the navigation system. Clinical results were assessed preoperatively and six months postoperatively. RESULTS: The modified gap-balancing technique resulted in significantly increased lateral femoral rollback (mean 16.3 mm) and lateral condylar liftoff (mean 1.3 mm) compared to the conventional group. The modified technique comprised an average of 2.1 mm less distal femoral resection and an average of 4° less external rotation and 3.5° more flexion of the femoral component compared with the control group. Average tibial resection height was 1.1 mm greater and average tibial slope was 0.5° elevated compared to the control group. A neutral leg axis was achieved in all cases. Results showed no significant differences in clinical scores between groups. CONCLUSION: A partial navigation solely of the tibial cut can securely restore the leg axis. Modification of the surgical technique can possibly reproduce more physiological knee kinematics with higher lateral femoral rollback in flexion without midflexion instability. This might help reduce postoperative problems with the new implant and thus reduce the amount of unsatisfactory results. Despite equal short-term results, mid- to long-term results are needed to prove whether or not this correlates with better clinical results and at least equal implant longevity.

Postoperative Vitamin D Surveillance and Supplementation in Revision Total Knee Arthroplasty Patients: A Retrospective Cohort Analysis.

This study was a retrospective cohort analysis of 20 patients who underwent 23 revision total knee arthroplasty procedures in a single geographic region of the United States from January 2015 to February 2023. We analyzed their 25-OH vitamin D levels preoperatively and postoperatively at 1 month, 3 months, 6 months, 1 year, and 2 years. We categorized their supplementation regimens by dose: none, low dose (1000 IU and below), medium dose (1001-5000 IU), and high dose (>5000 IU). We found that there was a high incidence of vitamin D deficiency in this patient population.

High rates of vitamin D insufficiency among patients presenting for total knee arthroplasty.

Widely varying prevalence of vitamin D deficiency has been reported in patients presenting for total knee arthroplasty (TKA). The primary aim of this study was to determine vitamin D levels in TKA patients and to compare to patients already routinely evaluated for vitamin D levels, patients with fragility fractures of the distal radius (DRF). There is significant overlap between patients presenting for TKA and with DRF, both in terms of medical comorbidities and overall health status, making these populations suitable comparative cohorts. Wefound that all patients presenting for TKA consultation had vitamin D insufficiency and 33% had vitamin D deficiency, compared to only 37% and 14% in the DRF cohort, a patient population routinely evaluated for vitamin D due to the high risk of deficiency. Furthermore, patients with DRF had higher levels of vitamin D before (38 ± 16 vs. 23 ± 5) and after vitamin D supplementation (39 ± 17 vs. 33 ± 10), suggesting that patients presenting for TKA are at even higher risk of vitamin D insufficiency than patients presenting with DRF. Reassuringly, supplementation successfully corrected 39.0% and 55.8% of patients in the DRF and TKA cohorts, respectively.

Good accuracy of the Phase III Oxford Mobile Bearing Unicompartmental Knee Instrumentation.

BACKGROUND AND PURPOSE: Unicompartmental knee arthroplasty (UKA) needs careful balancing of flexion/extension (F/E) gaps to prevent dislocation of the mobile meniscal bearing. Assessment of gaps is based on the surgeon's subjective insertion force of a feeler gauge with different thicknesses and/or the lift-off of a trial meniscal bearing. However, the accuracy of this method remains unclear. We assessed the accuracy of the technique. PATIENTS AND METHODS: A consecutive series of 33 UKAs in 32 patients (mean age 64 years, 24 women) were balanced using the Oxford Phase III (OP III) Instrumentation. The recommended technique for F/E gap assessment was performed using different feeler gauges with 1-mm increments and the meniscal bearing lift-off tests according to surgical technique. A tensiometer was inserted and both gaps were maximally distracted by hand. Measurements in mm were recorded and analyzed with a reading of 90 N for both gaps in 20 and 90 degrees of flexion. RESULTS: The gaps measured were 12 (11-18) mm in extension and 13 (11-18) mm in 90 degrees of flexion. The difference between the gaps was 0.4 (-0.5 to 1.0) mm (p < 0.001). There were no statistically significant gender differences regarding composite implant thickness, laxity, flexion gap, extension gap, or gap difference. INTERPRETATION: OP III instrumentation using feeler gauges and the lift-off test provides accurate balancing of F/E gaps with an accuracy of less than 1 mm.

Current fit of medial and lateral unicompartmental knee arthroplasty.

Whether failure in unicompartmental knee arthroplasty (UKA) is related to implant design remains unclear. We hypothesize that current available UKAs fit within 2 mm. Forty-eight CTs of cadaveric knees were compared to current available UKA brands. Overall no-fit compared to at least one component within 2 mm is high (91.7%) and worse for males (100%) compared to females (833%). Good fit was observed for the medial but not for the lateral tibia plateau. Seven males (29.2%) had larger dimensions of more than 2 mm. For the widest UKA brand, 12 (57%) males and 2 females (8. 3%) had lateral femoral condyles 3 mm larger. Current UKA's in our sample population fit less on the lateral tibia and on femoral condyles.

Does a modified gap-balancing technique result in medial-pivot knee kinematics in cruciate-retaining total knee arthroplasty? A pilot study.

BACKGROUND: Normal knee kinematics is characterized by posterior femorotibial rollback with tibial internal rotation and medial-pivot rotation in flexion. Cruciate-retaining TKAs (CR-TKAs) do not reproduce normal knee kinematics. QUESTIONS/PURPOSES: We hypothesized a more anatomic reconstruction of the medial femoral condyle, simultaneously preserving the tension of the PCL and medial collateral ligament, resulted in (1) medial-pivot rotation and tibial internal rotation, (2) lateral femoral rollback, and (3) reduced liftoff. PATIENTS AND METHODS: We compared 10 patients who underwent CR-TKA using the new technique at their 1-year followup to a matched control group of nine patients using a traditional gap-balancing technique at their 2- to 4-year followup. All patients received lateral radiographs in extension and flexion, which we utilized for three-dimensional implant matching to calculate tibial internal rotation, lateral rollback, and lateral liftoff in extension and flexion. RESULTS: The new gap-balancing technique resulted in a median of 3.5° tibial internal rotation with 2.7-mm rollback of the lateral femoral condyle relative to the medial condyle in flexion, which was different from the control group. We found no differences in liftoff between the groups. CONCLUSIONS: The new technique resulted in tibial internal rotation with flexion and lateral rollback comparing the lateral to the medial condyle in flexion, but no differences in condylar liftoff. These preliminary results were comparable to published kinematic results of an asymmetric CR-TKA or medial-pivot CR-TKA but not to symmetric CR-TKA.