Tibial Resection Research Articles

CT Analysis of the Posteromedial Neurovascular Bundle in Patients with End Stage Ankle Arthritis for Planning of Total Ankle Replacement Surgery

Category: Ankle Arthritis; Ankle Introduction/Purpose: Aim of this study is to identify reliable anatomical landmarks of the posterior tibial neurovascular bundle during Total Ankle Replacement (TAR) to minimise the risk of iatrogenic injury. Secondary aim is to identify if there is associated translation of the bundle when anterior translation of the talus is present. Methods: A radiological landmark protocol was devised to create a consistent method for measuring the relations of the bundle to the tibia, talus and medial gutter line when measured at levels mimicking those of resection undertaken in TAR. Analysis between patients with and without anterior subluxation was undertaken. Results: Total of 42 ankles were reviewed with 38% patient having anterior translation of the talus. At the tibiotalar joint, the bundle lies less than 5mm lateral to the medial gutter line and less than 8mm posterior to the posterior tibia. The same measurements at 10mm superior to the tibiotalar joint are less than 8mm and less than 6.5mm respectively. At 5mm distal to the dome of the talus, the bundle is less than 4mm lateral to the medial gutter line and between 8.4-16.0mm posterior to the posterior talus. The bundle to posterior tibia distance does not increase in the sagittal plane for patients with anterior subluxation of the talus. Conclusion: This study provides relevant guidance for surgeons to use intraoperatively when undertaking tibial and talus resections in TAR to identify their relations to the vulnerable neurovascular structures. The measurements of this study indicate for the first time that there is not an increased risk of iatrogenic injury during bone resection at the tibia in patients with anterior subluxation of the talus.

The German Arthroscopy Registry DART: what has happened after 5 years?

PurposeThe German Arthroscopy Registry (DART) has been initiated in 2017 with the aim to collect real-life data of patients undergoing knee, shoulder, hip or ankle surgery. The purpose of this study was to present an overview of the current status and the collected data thus far.MethodsData entered between 11/2017 and 01/2022 were analyzed. The number of cases (each case is defined as a single operation with or without concomitant procedures) entered for each joint, follow-up rates and trends between different age groups (18–29 years, 30–44 years, 45–64 years, ≥ 65 years) and across genders, and quality of life improvement (pre- vs. 1 year postoperative EQ visual analogue scale [EQ-VAS]) for frequently performed procedures (medial meniscus repair [MMR] vs. rotator cuff repair [RCR] vs. microfracturing of the talus [MFX-T]) were investigated.ResultsOverall, 6651 cases were entered into DART, forming three distinct modules classified by joint (5370 knee, 1053 shoulder and 228 ankle cases). The most commonly entered procedures were: knee: partial medial meniscectomy (n = 2089), chondroplasty (n = 1389), anterior cruicate ligament reconstruction with hamstring autograft (n = 880); shoulder: sub acromial decompression (n = 631), bursectomy (n = 385), RCR (n = 359); ankle: partial synovectomy (n = 117), tibial osteophyte resection (n = 72), loose body removal (n = 48). In the knee and shoulder modules, middle-aged patients were the predominant age group, whereas in the ankle module, the youngest age group was the most frequent one. The two oldest age groups had the highest 1-year follow-up rates across all modules. In the knee and shoulder module, 1-year follow-up rates were higher in female patients, whereas follow-up rates were higher in male patients in the ankle module. From pre- to 1-year postoperative, MFX-T (EQ-VAS: 50.0 [25–75% interquartile range: 31.8–71.5] to 75.0 [54.3–84.3]; ∆ + 25.0) led to a comparably larger improvement in quality of life than did MMR (EQ-VAS: 70.0 [50.0–80.0] to 85.0 [70.0–94.0]; ∆ + 15.0) or RCR (EQ-VAS: 67.0 [50.0–80.0] to 85.0 [70.0–95.0]; ∆ + 18.0).ConclusionDART has been sufficiently established and collects high-quality patient-related data with satisfactory follow-up allowing for a comprehensive analysis of the collected data. The current focus lies on improving patient enrolment and follow-up rates as well as initiating the hip module.

Neutral Mechanical Alignment Alters the Native Distal Femoral Joint Line: A Virtual Three-Dimensional Planning Total Knee Arthroplasty Study

BackgroundAlternative alignment concepts have garnered great interest in an effort to improve patient satisfaction following primary total knee arthroplasty (TKA). The purpose of this study is to determine variation or deviation from an individual’s native joint line in primary TKA using neutral mechanical versus a restricted kinematic technique. MethodsAn institutional review board–approved prospective cohort study was performed evaluating the effect of neutral mechanical alignment (nMA) versus a restricted kinematic alignment (rKA) on the native joint line in 100 consecutive patients undergoing primary TKA. Using preoperative computed tomography and intraoperative 3-dimensional software, 2 virtual preoperative plans were created: nMA and rKA. Templated bone resections were recorded. Change in joint line was calculated using known implant planar thickness and planned bone resection. ResultsnMA yielded significantly greater deviation from the patient’s native joint line along the lateral compartment of the knee (lateral distal femoral condyle, lateral posterior femoral condyle, lateral tibial resection). With nMA, the lateral distal femoral joint line was distalized by a mean 4.3 versus 2.6 mm using rKA technique (P < .001). In rKA, >60% of knees had <3 mm of deviation from the native lateral posterior femoral offset, whereas in nMA, >95% of knees had ≥3 mm change in the lateral posterior femoral condylar offset. ConclusionnMA-TKA resulted in statistically larger joint line deviations compared to rKA-TKA, most notably along the lateral distal femoral condyle joint line. Further analysis is needed to determine the clinical consequences of joint line deviation from the native anatomy using nMA as the target for primary TKA.

Augmented reality-aided unicompartmental knee arthroplasty

PurposeTo illustrate a surgical technique for augmented reality (AR)-assisted unicompartmental knee arthroplasty (UKA) and report preliminary data.MethodsWe developed an AR-based navigation system that enables the surgeon to see the tibial mechanical axis superimposed on the patient’s leg in addition to the tibial cutting angle. We measured the tibial resection angle in 11 UKAs using postoperative radiographs and calculated the absolute difference between preoperative target angle and postoperative measured angle. The target angle was determined for each patient: mean values were 0.7° ± 1.0° varus in coronal alignment and 5.3° ± 1.4° posterior slope in sagittal alignment.ResultsThe angles measured on postoperative radiographs were 2.6° ± 1.2° varus in the coronal plane and 4.8° ± 2.5° posterior slope in the sagittal plane. The absolute differences between the target and measured angles were 1.9° ± 1.5° in coronal alignment and 2.6° ± 1.2° in sagittal alignment. No patients experienced complications, including surgical site infection and periprosthetic fracture.ConclusionThe AR-based portable navigation system may provide passable accuracy in terms of proximal tibial resection during UKA.Level of EvidenceIV

Outcome of Patients in Term of Range of Motion after Total Knee Arthroplasty with all Poly Implants

Objective: To evaluate the outcome of patients in term of range of motion after total knee arthroplasty with all poly implants. Study Design: Retrospective study Place and Duration of Study: Department of Orthopaedics, Sahara Medical College, Narowal from 1st April 2021 to 31st March 2022. Methodology: Sixty various patients who came for total knee arthroplasty were selected on the basis of their conditions. Patients were divided into two inserts groups for understanding the better outcome results in terms of range of motion (ROM). Thirty patients having fixed bearing and other 30 patients having mobile bearing inserts will all poly implants. A standardized medial-parapatellar approach was taken for surgical procedure and resection of primary tibia was done. Pain function and evaluation was performed through knee society scoring (KSS) as well as VAS score and goniometer was used for analyzing range of motion which was defined as degree of flexion of knee subtracting from number of extension-defect. Results: There was no significant difference in either the gender or ages of both implants selected patients However the mobile bearing group patients has a better BMI value than the fixed bearing implant patients. In term of range of motion mobile bearing group patients had a higher ROM value than the fixed bearing operated patients in case of overall change in range of motion analysis. The Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index, score showed a significant change with an increased value observed in mobile bearing implant patients. Conclusion: Visual analogue pain score show significant difference in mobile and fixed bearing group. In terms of range of motion, mobile implants show better outcome in contrast to fixed bearing group. Keywords: Knee implants, Mobile, Fixed bearing, Outcomes, Osteolysis

Reconstruction With a 3D-Printed Megaprosthesis With Ankle Arthrodesis After Distal Tibial Tumor Resection.

Reconstruction after en bloc resection of the distal tibia has remained an unsettled issue despite many attempts with bone grafts or prostheses in the past. Failures of the previous methods have been attributed to inadequate mechanical strength, poor articular stability, failed osseointegration, and poor soft tissue coverage. To overcome these shortcomings, we designed and applied a 3D-printed megaprosthesis with ankle arthrodesis. A total of 13 patients underwent resection of a distal tibial tumor and reconstruction with a 3D-printed distal tibial megaprosthesis between January 2017 and November 2020. Mean age was 14.9±6.5 years. Diagnoses included 11 cases of osteosarcoma and 1 case each of low-grade phosphaturic mesenchymal tumor and rhabdomyosarcoma. Baseline characteristics, operative data, complication profiles, and oncologic, and functional outcomes were reviewed and analyzed. All 13 cases attained a wide or marginal resection. During a mean follow-up of 26.8±10.6 months, 1 patient experienced local recurrence and distant metastasis, whereas 3 other patients only developed distant metastasis. Periprosthetic infection subsequent to paronychia occurred in 1 patient 24 months after the operation. No other complications were observed. By the last follow-up, the mean MSTS-93 score was 28.0±1.5. In this relatively small cohort with short-term follow-up, reconstruction with the 3D-printed megaprosthesis with ankle arthrodesis was found to be a safe and efficacious method after resection of a distal tibial malignancy.

Total Knee Arthroplasty Using Adjusted Restricted Kinematic Alignment for the Treatment of Severe Varus Deformity: Technical Note.

ObjectiveTo describe a new alignment technique of adjusted restricted kinematic alignment (arKA) for the treatment of severe varus deformity in total knee arthroplasty.MethodsThree female patients (three severe varus knees) who underwent navigation‐assisted total knee arthroplasty (TKA) using arKA from April 2020 to September 2020 were included in this study, with an average age of 71.33 years (range, 61 to 80 years). General anesthesia was given to all patients. Intraoperative observations including tibia resection angle, frontal femoral angle, axial femoral angle, medial and lateral gap in the extension and flexion positions and joint line translation were recorded. Also, operation duration and drainage volume were recorded. Radiographic parameters including the mechanical axis (α), coronal femoral component angle (β), coronal tibial component angle (γ), sagittal femoral component angle (δ), tibial posterior slope angle (ε), femoral‐patella angle (θ), and femoral notching were assessed. Clinical evaluation was performed using the Hospital for Special Surgery (HSS) Score and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Score. Both individual and mean measurement data were displayed.ResultsThe mean tibial resection was 4.00° varus (range, 3° to 5°), and the mean frontal femoral angle was 3.67° varus (range, 3° to 4°) in extension. The flexion lateral gap was wider than the medial gap with a mean laxity of 1.34 mm. Moreover, the mean axial femoral angle was 2.67° external (range, 0° to 6°) in flexion, and the mean joint line translation was 1.00 mm proximal (range, 0 to 3 mm). In addition, the mean preoperative mechanical axis was 156.22° (range, 153.65° to 158.90°) and the mean postoperative mechanical axis was 174.04° (range, 173.83° to 174.17°) with a mean correction of 17.82°. The mean femoral angle was 92.60° (range, 91.29° to 93.30°) and the mean tibial angle was 86.95° (range, 86.83° to 87.04°) in coronal plane. The HSS score improved from an average of 46.67 points (range, 42 to 51) preoperatively to 83.67 points (range, 81 to 86) at 3 months postoperatively. The mean WOMAC score was 16.33 points at 3 months postoperatively.ConclusionsThe new alignment technique of arKA aims to balance the flexion and extension gap without extensive releases of soft tissue and restore the native pre‐arthritic alignment, may be a promising alignment strategy for treating severe varus deformity. However, further study and comparison with other alignment techniques is needed.

Navigated, gap-balanced, adjusted mechanical alignment achieves alignment and balancing goals in a very high percentage but with partially non-anatomical resections.

Navigated, gap-balanced adjusted mechanical alignment (AMA) including a 0° varus tibial cut and modification of angles and resections of the femoral cuts to obtain optimal balance accepting minor axis deviations. Objectives of this study were (1) to analyse to what extent AMA achieves the goals for leg alignment and gap balance, and (2) in what percentage non-anatomical cuts are needed to achieve these goals. Out of 1000 total knee arthroplasties (TKA) all varus knees (hip-knee-ankle (HKA) angle < 178°; n = 680) were included. All surgeries were performed as computer assisted surgery (CAS) in AMA technique. CAS data at the end of surgery were analysed with respect to HKA and gap-sizes. All bone cuts were quantified. Depending on the amount of deformity, a subgroup analysis was performed. It was analysed whether the amount of deformity influences the non-anatomical cuts by correlation analysis. AMA reached the goals for postoperative HKA (3° corridor) in 636 cases (93.5%). While extension and flexion gap balance were achieved in more than 653 cases (96%), flexion and extension gap size were equalled in 615 knees (90.4%). The resections of the lateral tibia plateau and distal and posterior medial femoral condyle were anatomical (Tibia: 7.0 ± 1.7mm; medial condyle distal: 7.8 ± 1.4mm; medial posterior: 8.2 ± 1.8mm). The number of non-anatomical resections for those cuts were low; 67 (9.9%); 24 (3.5%); 32 (4.7%). For the medial tibia plateau and the lateral posterior condyle, the cuts were non-anatomical in a high percentage of cases; Tibia: 606 (89.1%), lateral posterior condyle: 398 (58.5%). Moderate but significant correlations were found between resection differences and amount of deformity (medio-lateral: tibia: 0.399; distal femur: 0.310; posterior femur: 0.167). No correlations were found between resection differences and gap values. AMA reaches the intended target for HKA and gap balance in over 612 (90%) of cases and maintains the medial femoral condyle anatomically. Non-anatomical tibial resection causes increased external rotation of the femoral component and by that non-anatomical cut of the posterior lateral condyle. Nonanatomical resections of AMA might be one reason for the persisting high rate of unsatisfied patients after TKA. Anatomical and individual alignment philosophies might help to reduce this rate of dissatisfaction.

What Is the Alignment and Balance of a Total Knee Arthroplasty Performed Using a Calipered Kinematic Alignment Technique?

We simulated calipered kinematic alignment total knee arthroplasty (cKATKA) using alignment data and ligament tensions acquired during 607 consecutive robotic-assisted TKAs performed using a dynamic ligament tensor. The distal femur was resected parallel to the native joint line accounting for cartilage loss. The proximal tibial resection necessary to achieve extension gap balance was calculated for each knee. Similarly, symmetric posterior condylar resections prescribed by this method were simulated and the tibial resection needed to achieve a balanced flexion gap calculated. Finally, the resultant limb alignment and degree of joint balance in both flexion and extension of each knee were determined and categorized according to the preoperative knee alignment. Increasing preoperative varus deformity required a greater tibial varus cut to achieve a balanced extension gap (P < .0001). There was no correlation between tibial varus angle and flexion gap balance (P > .1). For mild varus deformities 81% and 95% of knees could be balanced and have an overall limb alignment within 3° and 5° from the mechanical axis respectively. For knees with moderate-severe varus, only 37% and 74% could be balanced within these alignment boundaries (P < .01). Overall, 95% of these simulated knees could be balanced with an overall alignment within 0° ± 5°. However, 50% of the simulated TKAs had looser medial gaps in flexion compared to the lateral gap. Application of the cKATKA method can yield TKAs within 0° ± 5° of mechanical axis alignment by simply adjusting the proximal tibial resection without ligament releases. However, an undesirable flexion gap balance was predicted in nearly 50% of the TKAs.

Effect of an Endoprosthetic Reconstruction Tube and Medial Gastrocnemius Flap on Extensor Mechanism Function After Oncologic Prosthesis Reconstruction of the Proximal Tibia

BackgroundExtensor mechanism reconstruction after the proximal tibial resection and implantation of a megaprosthesis is challenging. In this study, we evaluated the effectiveness of the Trevira tube and medial gastrocnemius flap in restoring extensor mechanism following the resection of proximal tibial tumor and implantation of megaprosthesis. MethodsForty patients who underwent endoprosthetic implantation following the resection of proximal tibial tumor and patellar tendon reconstruction with the Trevira tube and medial gastrocnemius flap were included. The outcome measures were knee range of motion, extensor mechanism function, patellar position, and limb function subjectively evaluated through Toronto Extremity Salvage Score and objectively through Musculoskeletal Tumor Society score. The mean follow-up of the patients was 6.1 years. ResultsThe patellar position was normal in 28 (70%) patients, patella baja in 3 (7.5%) patients, and patella alta in 9 (22.5%) patients. The mean active knee range of motion was 98.9 ± 17° (range: 85°-125°). Extension lag was present in 7 (17.5%) patients (range: 5°-20°). The mean Toronto Extremity Salvage Score of patients was 92.1 ± 6.9% (range: 85-100). The mean Musculoskeletal Tumor Society score of the patients was 87.7 ± 13 (range: 73.3-100). Postoperative complications included aseptic wound dehiscence (2 patients), aseptic loosening of the tibial component (1 patient), periprosthetic fracture in the femur (2 patients), and wound infection (1 patient). ConclusionTrevira tube combined with gastrocnemius flap augmentation is a suitable procedure for restoring extensor mechanism after proximal tibial resection and megaprosthesis implantation.

Alignement Cinématique inversé pour les Prothèses Totales de Genou

Patient specific alignment might improve clinical outcomes in total knee arthroplasty (TKA). Different alignment concepts are described, each providing specific features with theoretical benefits or possible disadvantages. Inverse kinematic alignment (iKA) is a new patient specific alignment concept with excellent reported clinical outcome and patient satisfaction at short-term follow-up. iKA is a tibia-first, gap balancing technique restoring the native tibial joint line obliquity (JLO). In each patient, within boundaries, equal medial and lateral tibial resections are performed, compensating for cartilage and bone loss. We describe the surgical technique of iKA using a robotic assisted system (Mako, Stryker, Kalamazoo, USA). A case series of 100 consecutive iKA cases is assessed and the bony resections and resection angles are reported. Both in the coronal plane and axial plane, iKA might offer advantages over existing alignment strategies, possibly providing optimal clinical outcome and durable long-term survival, regardless of the alignment is varus, neutral or valgus.

Predictive Gap-balancing Reduces the Extent of Soft-tissue Adjustment Required After Bony Resection in Robot-assisted Total Knee Arthroplasty—A Comparison With Simulated Measured Resection

BackgroundTo understand the extent and frequency of soft-tissue adjustment required to achieve mediolateral (ML) balance in measured resection (MR) vs gap-balancing (GB) total knee arthroplasty, this study compared ML balance and joint laxity throughout flexion between the 2 techniques. The precision of predictive GB in achieving ML balance and laxity was also assessed. MethodsTwo surgeons performed 95 robot-assisted GB total knee arthroplasties with predictive balancing, limiting tibial varus to 3° and adjusting femoral positioning to optimize balance. A robotic ligament tensioner measured joint laxity. Planned MR (pMR) was simulated by applying neutral tibial and femoral coronal resections and 3° of external femoral rotation. ML balance, laxity, component alignment, and resection depths were compared between planned GB (pGB) and pMR. ML balance and laxity were compared between pGB and final GB (fGB). ResultsThe proportion of knees with >2 mm of ML imbalance in flexion or extension ranged from 3% to 18% for pGB vs 50% to 53% for pMR (P < .001). Rates of ML imbalance >3 mm ranged from 0% to 9% for pGB and 30% to 38% for MR (P < .001). The mean pMR laxity was 1.9 mm tighter medially and 1.1 mm tighter laterally than pGB throughout flexion. The mean fGB laxity was greater than the mean pGB laxity by 0.5 mm medially and 1.2 mm laterally (P < .001). ConclusionMR led to tighter joints than GB, with ML gap imbalances >3 mm in 30% of knees. GB planning improved ML balance throughout flexion but increased femoral posterior rotation variability and bone resection compared to MR. fGB laxity was likely not clinically significantly different than pGB.

Inverse Kinematic Alignment for Total Knee Arthroplasty

Patient specific alignment might improve clinical outcomes in total knee arthroplasty (TKA). Different alignment concepts are described, each providing specific features with theoretical benefits or possible disadvantages. Inverse kinematic alignment (iKA) is a new patient specific alignment concept with excellent reported clinical outcome and patient satisfaction at short-term follow-up. iKA is a tibia-first, gap balancing technique restoring the native tibial joint line obliquity (JLO). In each patient, within boundaries, equal medial and lateral tibial resections are performed, compensating for cartilage and bone loss. We describe the surgical technique of iKA using a robotic assisted system (Mako, Stryker, Kalamazoo, USA). A case series of 100 consecutive iKA cases is assessed and the bony resections and resection angles are reported. Both in the coronal plane and axial plane, iKA might offer advantages over existing alignment strategies, possibly providing optimal clinical outcome and durable long-term survival, regardless of the alignment is varus, neutral or valgus.

Impact of patient, surgical, and implant design factors on predicted tray-bone interface micromotions in cementless total knee arthroplasty.

Micromotion magnitudes exceeding 150 µm may prevent bone formation and limit fixation after cementless total knee arthroplasty (TKA). Many factors influence the tray-bone interface micromotion but the critical parameters and sensitivities are less clear. In this study, we assessed the impacts of surgical (tray alignment, tibial coverage, and resection surface preparation), patient (bone properties and tibiofemoral kinematics), and implant design (tray feature and surface friction) factors on tray-bone interface micromotions during a series of activities of daily living. Micromotion was estimated via three previously validated implant-bone finite element models and tested under gait, deep knee bending, and stair descent loads. Overall, the average micromotion across the tray-bone cementless contact interface ranged from 9.3 to 111.4 µm, and peak micromotion was consistently found along the anterior tray edge. Maximizing tibial coverage above a properly sized tibial tray (an average of 12.3% additional area) had minimal impact on micromotion. A 1 mm anterior tray alignment change reduced the average micromotion by an average of 16.1%. Two-degree tibial angular resection errors reduced the area for bone ingrowth up to 48.1%. Differences on average micromotion from ±25% changes in bone moduli were up to 75.5%. A more posterior tibiofemoral contact due to additional 100 N posterior force resulted in an average of 79.3% increase on average micromotion. Overall, careful surgical technique, patient selection, and controlling kinematics through articular design all contribute meaningfully to minimizing micromotion in cementless TKA, with centralizing the load transfer to minimize the resulting moment at the anterior tray perimeter a consistent theme.

Proximal Branching of the Anterior Tibial Artery From the Popliteal Artery Increases the Risk of Vascular Injury During Total Knee Arthroplasty: A Retrospective Analysis Using Preoperative Magnetic Resonance Imaging and Intraoperative Findings.

IntroductionArterial injury following total knee arthroplasty (TKA) can be life-threatening. There are some anatomical variations in the popliteal artery (PA) and its branches. In most cases, the PA branches into the anterior tibial artery (ATA) and posterior tibial artery (PTA), which are usually distal to the height of tibial resection in TKA. However, some cases show that the PA branches into the ATA and PTA proximal to the height of tibial resection in TKA. This study aimed to assess the distance from the posterior cortex of the proximal tibia to the anterior wall of the PA or ATA at the height of the tibial cut line, during TKA in the distal and proximal branch groups.Methods129 patients (6 patients in the proximal branch group and 123 patients in the distal branch group) were enrolled for this study. For prediction of the distance from the posterior cortex of the proximal tibia to the anterior wall of the PA or ATA, preoperative sagittal and coronal magnetic resonance images and postoperative radiographs were evaluated.ResultsThe distance between the posterior cortex of the proximal tibia and the anterior wall of the PA or ATA at the height of the tibial cut line was 1.8 ± 1.1 mm in the proximal branch group and 6.1 ± 2.6 mm in the distal branch group, which was significantly closer in the proximal group (P < .05).DiscussionThe rate of proximal branching was 4.7%. This study clarified that the proximal branching of the ATA from PA significantly decreased the distance between the posterior cortex of the proximal tibia and the anterior wall of the artery.ConclusionsThe proximal branch group has a high risk for arterial injury as the artery may be close to the saw, and appropriate retraction should be performed.

Difference between medial and lateral tibia plateau in the coronal plane: importance of preoperative evaluation for medial unicompartmental knee arthroplasty

BackgroundSetting bone cutting levels for different joint line orientations of the medial and lateral tibia plateaus in individual patients is not clear. We aimed to evaluate the difference between joint line orientation of the medial and lateral tibia plateaus relative to the horizontal line of mechanical axis of tibia as tibial plateau difference (TPD) for an optimal tibial bone cut in medial unicompartmental knee arthroplasty (UKA) and determine which factors could influence TPD. We aimed to investigate the effect of preoperative TPD on polyethylene liner size in medial UKA.MethodsTPD in the coronal plane were measured in 181 female patients (181 knees). To determine the morphology of proximal tibia according to the severity of osteoarthritis, the patients were classified into three groups based on diagnosis and treatment: 80 who underwent robot-assisted medial UKA, 45 who underwent total knee arthroplasty (TKA), and 56 with early-stage osteoarthritis (OA) who had conservative management. Also, we divided the medial UKA group into two groups according to TPD (greater than or less than 5 mm) and compared polyethylene liner sizes.ResultsNo significant difference was observed in TPD (p = 0.662), difference between the medial and lateral femoral condyle levels (p = 0.54), medial proximal tibial angle (p = 0.169), or posterior tibial slope (p = 0.466) among the three groups. Increased TPD was significantly associated with increased mechanical femorotibial angle(mFTA) (p < 0.01). The medial UKA group was divided into two groups according to TPD greater or less than 5 mm. Thicker polyethylene liners were used for groups with TPD greater than 5 mm (8.5 ± 0.7 mm versus 8.2 ± 0.3 mm, p = 0.01). Additionally, the proportion of patients using the thinnest polyethylene (8 mm) in each TPD group (greater or less than 5 mm) was higher in patients with TPD less than 5 mm (82.4% versus 58.7%, p = 0.038).ConclusionsPreoperative measurement of TPD is important to help surgeons predict the most appropriate bone cutting level in the coronal plane in primary medial UKA. Tibial bone resection would be likely to be thicker than needed in patients with increased TPD in medial UKA.

Proximal tibial morphology is associated with risk of trauma to the posteromedial structures during tibial bone resection reproducing the anatomical posterior tibial slope in bicruciate-retaining total knee arthroplasty

BackgroundA tibial cut with the native posterior tibial slope (PTS) is a theoretical prerequisite in bicruciate-retaining total knee arthroplasty (BCRTKA) to regain physiological knee kinematics. The present study reveals tibial morphological risk factors of trauma to the posteromedial structures of the knee during tibial bone resection in BCRTKA. MethodsFifty patients undergoing BCRTKA for varus knee osteoarthritis were analyzed. A three-dimensional tibial bone model was reconstructed using a computed tomography-based preoperative planning system, and the coronal tibial slope (CTS) and medial PTS (MPTS) were measured. Then, we set the simulated tibial cutting plane neutral on the coronal plane, posteriorly inclined in accordance with the MPTS on the sagittal plane, and 9 mm below the surface of the subchondral cortical bone (i.e., 11 mm below the surface of the cartilage) of the lateral tibial plateau. The association between the tibial morphology and the distance from the simulated cutting plane to the semimembranosus (SM) insertion (Dsm) was analyzed. ResultsOf the 50 patients, 19 (38%) had negative Dsm values, indicating a cut into the SM (namely, below the posterior oblique ligament) insertion. The MPTS was negatively correlated with Dsm (r = −0.396, p = 0.004), whereas the CTS was positively correlated with Dsm (r = 0.619, p < 0.001). On multivariate linear regression analysis, the MPTS and CTS were independent predictors of Dsm. ConclusionIn the setting of tibial cuts reproducing the native MPTS in BCRTKA, patients with larger PTS and smaller CTS had more risk of trauma to the posteromedial structures.

Does bone penetration of cement differ by cement type and application time-point?

Intrusion of cement into bone is often considered an indirect indicator for implant stability in cemented joint replacement procedures. However, the influence of cement type (different viscosities/manufacturers) and application time-point on penetration of cements continues to be debated. This study aimed to quantify the effect of cement type and application time-point on the depth of penetration using porcine tibial specimens.Four different bone cements were applied to 60 resected porcine cadaveric tibias at three time-points within the working window (1, 2, and 3 min after dough time). Penetration was measured using computed tomography, utilizing two rigorous methods from the literature and a newly proposed volumetric method.Application time-point had a strong influence on the thickness of the cement layer above the resected tibia (0.25, 0.49, 0.73 mm at the three time-points). No significant variation in penetration depth metrics with cement type or application time-point was found, except percentage area covered by cement at 2 mm depth. This metric was significantly different between 1 and 3-minute time-points (12% and 6% respectively).Time-point of application had a significant influence on thickness of pure cement layer over resected bone. However, penetration depth was not significantly affected by cement type or application time-point. The clinical significance of these findings is that it may be better to apply cement relatively soon after dough time to avoid excessively thick cement mantle between implant and bone. Further, the choice of cement type may have minimal impact on cement penetration, indicating that long standing principles of good cement application maybe more important.

“In-house” Design and Use of 3-dimensional Printed Patient-specific Bone Tumor Resection Guides for Geometric Osteotomies in Sarcoma Surgery

Three-dimensional printing technology has rapidly advanced as a promising technology for preoperative planning, education, and surgical execution in orthopedic surgery. Use of patient-specific instrumentation in orthopedic oncology sarcoma cases can streamline complex osteotomies while providing safe margins based on predetermined osteotomy levels. We describe use of an “in-house” protocol to create patient-specific bone tumor resection guides for use in orthopedic oncology cases. The described protocol bypasses expensive outsourcing options and facilitates use of preoperative surgical simulation and intimate involvement of the surgical team in the guide design. We report on the successful design and use of three-dimensional printed patient-specific bone tissue resection guides in a case of proximal tibial parosteal osteosarcoma resection and reconstruction with a size-matched allograft, and in a case of a secondary pelvic chondrosarcoma resection.

Robotic arm-assisted posterior-stabilised total knee arthroplasty reduces the amount of tibial bone resection thickness without increasing the rate of postoperative flexion contracture in varus knees in the short term: Comparison with image-free navigated total knee arthroplasty.

This study aimed to compare the bone resection thickness, rate of minimal thickness insert usage, and postoperative range of motion (ROM) between robotic and navigated total knee arthroplasty (TKA). Fifty consecutive posterior-stabilised (PS) robotic TKA and 50 case-controlled PS navigated TKA were enroled. Bone resection thickness, rate of minimal thickness insert usage, and postoperative flexion contracture over 5° were statistically compared. The tibial bone resection thickness was significantly thinner in robotic TKA. The insert thickness was significantly lower, and the rate of minimal thickness insert usage was significantly higher in robotic TKA. The ROM at 3months postoperatively and the rate of postoperative flexion contracture were comparable between the two groups. Robotic TKA can reduce the tibial bone resection thickness and increase the rate of minimal thickness insert usage without increasing postoperative flexion contracture as compared with navigated TKA.