Role and Results of Constrained Insert in Computer-Assisted Primary Total Knee Arthroplasty: A Propensity-Matched Study.

Purpose: Mild ligament imbalance is often encountered in the mediolateral plane during complex primary total knee arthroplasty. A constrained (CP) polyethylene insert compatible with the primary femur is useful to manage these cases without the need to fall back on revision implants. The aim of the study was to define the correct indications of the use of a CP insert based on objective data from computer assisted surgery and to compare the early results of a CP insert with a standard posterior stabilized (PS) insert through one-to-one propensity score matching. Methods: This is a retrospective case study from a prospectively collected database. One-to-one matching without replacement was used with a caliper width of 0.2 to match the scores between CP (N = 64) and PS groups (N = 1624), resulting in equal covariate matching of PS (N = 64) and CP (N = 64) cohorts. Patients were assessed radiographically and functionally at a minimum follow-up of 3 years. Result: Average coronal and sagittal plane deformities were similar in both the group CP (varus 13.1 ± 5.2 valgus 13 ± 7.9) and the group PS (varus 13.4 ± 4.6 valgus 10.9 ± 8.6). The average residual medial lateral gap difference was significantly higher in group CP (3.8 ± 1.8) in comparison to group PS (1.3 ± 1) (P < .05). A CP insert was chosen where mild ligament imbalance of 3-5 mm persisted after medial soft tissue releases in a varus knee and in cases with residual medial collateral ligament laxity in valgus knees. Conclusions: Constrained insert used with the primary femoral component is a valuable option to handle mild ligamentous instability in complex primary total knee arthroplasty after mechanical alignment is achieved with computer navigation. Level of Evidence: III.

The "Wind Surf" Deformity-Correcting Fixed Flexion Deformity and Hyperextension in Bilateral CAS TKA.

Severe knee arthritis can result in complex coronal and sagittal angular deformities. Windswept deformity is used to describe a varus deformity and contralateral valgus deformity. We recognized a new sagittal pattern at the time of computer-assisted surgery (CAS) in total knee arthroplasty (TKA) in which one knee has a fixed flexion deformity (FFD), while the contralateral knee has a hyperextension deformity. We propose to define it as "wind surf" deformity mimicking the opposite pull of the wind and a surfer. The incidence of "wind surf" deformity in this series was 0.96% among a cohort of 2,291 bilateral TKAs performed between 2013 and 2018. Twenty-two patients were identified with an FFD of 5° to 20° on one knee and recurvatum of -5° to -20° on the contralateral knee. Additional bone resection and soft-tissue releases were performed for the FFD with a goal to maintain residual 1° to 3° of flexion. Minimal bone resection and soft-tissue disruption were performed on the knee with hyperextension with a goal to maintain 5° to 7° of flexion. These opposite strategies applied with the help of CAS prevented recurrence resulting in satisfactory clinical results at 2-year follow-up. The "wind surf" deformity variant should be identified in patients presenting with severe knee arthritis to guide surgical treatment, prevent recurrence, and obtain favorable clinical patient outcomes.

Management of Lateral Femoral Condyle Non-union with Autogenous Bone Graft in CAS Total Knee Arthroplasty.

Introduction: Neglected distal femur fractures often present with significant uncontained bone defects of the lateral femoral condyle (LFC) leading to a valgus deformity and lateral compartment arthritis. Case Report: Bone defect can be managed with the help of autogenous bone graft harvested from a distal femur cut and shaped in the form of an augment. The objective of using bone graft along with the primary femur was to restore bone stock in a young patient and prevent the use of an augment with a revision femur and intramedullary rod. Conclusion: The use of computer navigation helped in getting accurate components and overall alignment thus facilitating compression at the bone graft site and early union.

Subvastus Exposure Compared to Parapatellar Approach in Navigated Sequential Bilateral Total Knee Arthroplasty (SBTKA): A Prospective Randomized Study.

Subvastus approach preserves the quadriceps mechanism and may lead to improved early functional outcomes as compared with a parapatellar approach in primary knee arthroplasty. We performed a prospective randomized study to test the hypothesis if subvastus approach improves patient- and physician-reported outcomes in navigated sequential bilateral knee arthroplasty when compared with the standard parapatellar approach. A total of 93 patients were allotted in each group after power analysis and randomization done by computer-generated sequence: group S by subvastus approach and control group P by parapatellar approach. The patient's ability to walk without an aid, range of motion, blood loss, tourniquet time, complications, Knee Society Score (KSS), Knee Society Functional Score (KSFS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), High Flexion Knee Score (HFKS), and visual analog scale (VAS) for pain were recorded preoperatively and postoperatively at 2 and 6 weeks and 3, 6, and 12 months. Final follow-up was done at 2 years. There was no statistical difference in the patient's ability to achieve a straight leg raise (p = 0.88), walk without an aid (p = 0.25), leaving pain medication (p = 0.48), and mean duration of hospital stay (p = 0.58) between both groups. There was no difference in KSS, FS, KOOS, WOMAC, HFKS, and VAS at 2 weeks and later follow-ups. There was no significant difference in range of motion or lateral retinacular release in both groups. Blood loss was significantly less in group S (p < 0.05), but there was a higher rate of proximal wound dehiscence and delayed healing in subvastus group (p = 0.03). Subvastus approach does not improve patient- and physician-reported outcome measures except blood loss in computer-navigated sequential bilateral knee arthroplasty and has an increased incidence of wound healing problems. The Level of evidence for the study is I.

Do spacer blocks accurately estimate deformity correction and gap balance in total knee arthroplasty? A prospective study with computer navigation.

BACKGROUND: Spacer blocks are used commonly in knee arthroplasty to estimate gaps and ligament balance. Their use continues along with modern technology despite dearth of literature regarding their accuracy and reliability. This prospective study aims to determine the difference in values of gap and balance measurements between spacers and trials in computer assisted TKA. METHODS: 50 patients with moderate varus deformity of <20° undergoing primary TKA were recruited for this prospective study. After navigation assisted cuts and requisite ligament release, gaps and balance were recorded in extension and 90° flexion with spacer block followed by implant trials. RESULTS: There were 33 females and 17 males with average BMI of 28.2 ±â€¯5kg/m2. The average preoperative flexion deformity was 6.5°â€¯±â€¯4.4° and varus deformity was 8.2°â€¯±â€¯3.8°. Average difference of deformity in sagittal plane in extension between spacer and trial was 6.2° which was statistically significant (p = 0.001) implying that knee achieves more extension with spacer blocks as compared to trials because the blocks do not have posterior offset of the condyles. However, there was no difference between values of soft tissue balance and coronal plane correction between spacer blocks and trials in extension and 90° flexion (p > 0.05). CONCLUSION: Spacer blocks do not estimate extension space accurately with knee achieving 6.2 more flexion with trials as compared to spacer blocks when assessed for sagittal plane correction in extension. Spacer blocks should pass in easily in extension to avoid any flexion deformity when the actual trials are inserted.

Total knee arthroplasty in a case of diffuse idiopathic skeletal hyperostosis; challenges in ligament balancing and deformity correction.

INTRODUCTION: Diffuse skeletal idiopathic hyperostosis is a non-inflammatory systemic skeletal condition in which there is ossification of ligaments, tendons, and joint capsule. Although the radiological changes and clinical manifestation of diffuse idiopathic skeletal hyperostosis (DISH) in the spine have been well defined in the literature, the changes in the knee and their implications on knee replacement are unclear. CASE REPORT: A 60 year -year-old patient presented with pain, stiffness, and decreased arc of movement at the right knee. The X-rays showed ossification of the joint capsule, ligaments, and quadriceps expansion. The spine had has calcification of the anterior longitudinal ligament and '"wax drop' drop" enthesophytes. Based on the complete skeletal survey, a diagnosis of DISH was made. During knee arthroplasty, it was difficult to correct the deformity with a measured resection technique. Additional resection of 4 mm was done both from the distal femur and proximal tibia to correct the deformity and achieve optimal kinematics. This unpliable nature of the soft tissues due to enthesitis ossification of periarticular tissues led to decrease flexion postoperatively. CONCLUSION: Surgeons should keep the diagnosis of DISH in mind when dealing with a stiff knee and be prepared for additional bone resection with extensive soft tissue release to balance the prosthetic knee joint.

Computer navigation has no beneficial effect on blood loss and transfusion in sequential bilateral total knee Arthroplasty.

BACKGROUND: Bilateral total knee arthroplasty is associated with significant blood loss. Postoperative anaemia retards patients recovery, and blood transfusion increases the risk for major complications including infection. While strategies like hypotensive anaesthesia, tranexamic acid, bone wax and so on are useful to conserve blood, navigation has also shown to decrease blood loss and transfusion in unilateral knee arthroplasty. The aim of this study was to compare the blood loss and transfusion in sequential bilateral knee arthroplasty performed with or without navigation. MATERIALS AND METHODS: A retrospective case control cohort study of sequential bilateral knee arthroplasties was performed between 2 groups of 77 patients each, group N operated with navigation and group M operated without navigation. Both groups were matched for age, sex and body mass index. All patients were operated with similar surgical technique. The two cohorts were compared for blood loss calculated by three reliable methods. RESULTS: The preoperative haemoglobin (Hb) in group N was 12.83 ± 1.32 and group M was 12.58 ± 1.33 ( p = 0.24). The postoperative Hb taken day 4 before any blood transfusions was 8.60 ± 1.24 in group N and 8.54 ± 1.16 in group M ( p = 0.75). The average fall in Hb was 4.23 ± 1.08 in group N and 4.04 ± 1.19 in group M ( p = 0.31). There was no difference in blood loss between group N and M in all three methods; Gross equation ( p = 0.56), Hb dilution ( p = 0.24) and Hb balance ( p = 0.20). Need for blood transfusion was similar in group N and M ( p = 0.56). CONCLUSION: Blood loss and transfusion are equivalent in sequential bilateral total knee arthroplasty perform with or without navigation.

Safety and Efficacy of 6.2 mm Patellar Button in Resurfacing Less than 20 mm Thin Patella: A Matched Pair Analysis.

PURPOSE: Restoring the native patellar thickness after patellar resurfacing provides optimal function of the knee after arthroplasty and minimises complications related to the patellofemoral articulation. The aim of this study was to assess the usefulness of a thin patellar button (6.2 mm) in patients with a patella thickness of less than 20 mm during total knee arthroplasty. MATERIALS AND METHODS: This is a retrospective case control study. A total of 54 female patients with an intraoperative patellar thickness of ＜20 mm, resurfaced with a patellar button of 6.2 mm in thickness were identified (group 1). They were matched with 54 patients with a patellar thickness of 20-23 mm, resurfaced with a patellar button of 8 mm (group 2), based on age, sex, body mass index, and deformity. A clinical and radiological evaluation was done at a minimum 2-year follow-up. RESULTS: The preoperative mean patellar thickness was 18.94±1.07 mm and was restored to 19.06±0.79 mm in group 1, as compared to 21.63±0.99 mm and 21.72±0.99 mm in group 2. The mean postoperative range of motion was 122.22°±9.25° in group 1 and 123.52°±8.72° in group 2 (p=0.13). No patellar bone or button related complications were observed in any patient in either group. CONCLUSIONS: The 6.2 mm thin patella is useful to restore the native thickness in patients with a patellar thickness of less than 20 mm without risk of button fracture, loosening or overstuffing.

Effect of Closed Suction Drain on Blood Loss and Transfusion Rates in Simultaneous Bilateral Total Knee Arthroplasty: A Prospective Randomized Study.

PURPOSE: Simultaneous bilateral total knee arthroplasty (TKA) is associated with excessive blood loss and morbidity arising from postoperative reduction in hemoglobin (Hb). The purpose of this prospective randomized study was to determine if drains have any effect on blood loss, postoperative reduction in Hb levels and transfusion rates compared to no drainage in simultaneous bilateral TKAs. MATERIALS AND METHODS: Two hundred and thirty patients who underwent simultaneous bilateral TKA by a single surgeon were randomly allotted to drain or no-drain group (n=115 in each group). Postoperative Hb level, blood loss volume and transfusion rate were compared between the two groups. RESULTS: The mean postoperative Hb level (p=0.38), blood loss volume (p=0.33) and transfusion rate (p=0.52) in the drain group were not significantly different compared to the no-drain group. No statistical difference was found in terms of complications, readmissions and mortality rates between the two groups. CONCLUSIONS: No significant difference was observed in the two groups with respect to blood loss and blood transfusion. Non-drainage does not offer an advantage over drainage with respect to conserving blood in simultaneous bilateral TKA.

The effect of patellar replacement technique on patellofemoral complications and anterior knee pain.

Routine patella replacement with total knee arthroplasty has not been universally adopted because of associated patellofemoral complications such as anterior knee pain (AKP). In the proposed technique, the articular surface of the lateral facet of the patella is excised to the depth of the subchondral bone, and the medial facet is then cut parallel to the anterior surface. We evaluated any correlation between various radiographic parameters and AKP in 100 consecutive fixed-bearing posterior-stabilized total knee arthroplasties. There were no cases of fracture, avascular necrosis, subluxation, dislocation, patellar baja, or overstuffing of the patella. Anterior knee pain was present in 11% of cases, and no cases were severe or disabling. There were no correlations between AKP, range of motion, patellar size and shape, and any of the radiographic parameters.