Soft Tissue Balancing Research Articles

New technology: Custom made implants, patient-specific alignment, and navigation – How to convince my hospital it's worth it: Current concepts

Unicompartmental knee arthroplasty (UKA) faces significant challenges, including lower survival rates and higher revision rates than total knee arthroplasty (TKA). To address these issues, technological advancements like custom-made implants (CMI), patient-specific alignment (PSA), and computer-assisted systems (CAS) are being explored. These innovations aim to tailor procedures to individual joint morphology, soft tissue balance, and limb alignment, moving away from the traditional “one size fits all” approach. Early studies suggest that CMI may improve survival rates and patient-reported outcomes, though conclusive evidence is lacking. PSA shows potential for restoring pre-surgical alignment; however, its long-term benefits are uncertain. CAS improves implant placement precision and ligament balance; nevertheless, long-term survival data remain inconclusive. Moreover, economic and implementation challenges, such as cost and the need for specialized training, remain underexplored. While promising, further research is needed to fully understand the long-term efficacy and practical application of these technologies in UKA.

UNICOMPARTMENTAL KNEE ARTHROPLASTY: WHAT IS THE OPTIMAL ALIGNMENT CORRECTION TO ACHIEVE SUCCESS? THE ROLE OF KINEMATIC ALIGNMENT. STATE OFF THE ART REVIEW

Unicompartmental knee arthroplasty (UKA) is in many ways the ultimate kinematic operation as the express aim is to resurface the diseased side of the joint and restore pre-arthritic alignment and balance while maintaining integrity of both cruciate ligaments. An increasing body of knowledge relates the outcomes of UKA to pre-arthritic anatomy rather than an arbitrarily defined neutral. The Coronal Plane Alignment of the Knee (CPAK) classification provides a validated technique for calculating pre-arthritic limb alignment (the Arithmetic Hip-Knee-Ankle Ankle (aHKA)) and Joint Line Obliquity (JLO) and will enable a greater understanding of the interactions between pre-arthritic anatomy, choice of prosthetic position and outcomes. When pre-arthritic alignment is not taken into consideration a post-operative limb alignment of mild to moderate varus for medial UKA and moderate valgus for lateral UKA appears produces the best outcomes. When pre-arthritic anatomy is taken into account superior results have been reported with restoration of pre-arthritic limb alignment and joint line obliquity. Restriction boundaries have yet to be clearly defined for tibial component coronal and Hip-Knee-Ankle (HKA) angles when applying this new paradigm, but existing evidence would suggest a 60 varus limit for the tibial coronal angle may be a reasonable starting point. Lateral UKA has inherent differences in terms of tibial component positioning and ligament balance targets. Mobile bearing UKA demands a three-dimensional understanding of the effect of implant position on bearing stability. Modification of technique is necessary to produce anatomic tibia component angles with equipment designed for mechanical alignment. Robotic technology allows accurate understanding of pre-arthritic anatomy, precise reproduction of patient specific virtual planning, equally precise manipulation of soft tissue balance and future research using these platforms likely to further clarify in terms of ideal patient specific component and limb alignment targets.

A study of functional outcome of total hip arthroplasty with bone grafting

The effects of OA on large joints especially the lower extremities result in reduced mobility and marked physical impairment leading to loss of independence and an increase in use of health services. OA also leads to daily living activities and leads to substantial disability and dependence in walking, climbing stairs and rising from a seated position. THR is a successful and effective treatment option when symptoms deteriorate and is at an advanced stage of the disease. Bone grafts can be used in conjunction with cemented all polyethylene cups, cement less implants as well as reinforcement rings and cages. The use of bone grafts and its long-term survival in the acetabulum have been reported to vary from 84% at years to 52% at 25 years. This study used autogenous morselized impaction bone grafting with a cementless press-fitting cup, and the midterm results were excellent to good. Grafting aids in the stable installation of implants and the effective rebuilding of bone stock. With these fantastic outcomes, total hip arthroplasty with bone grafting can be thought of as offering complete relief, sufficient stability, and an amazing range of motion in extremely painful, refractory hips, provided that it is carried out with careful consideration for patient selection prior to surgery, intraoperative soft tissue balancing, proper overall alignment of the prosthesis, and postoperative patient rehabilitation. Complete hip replacement with bone grafting is a rather safe and certain operation when performed by a qualified professional or guide.

Predictive factors for deep medial collateral ligament release in adjusted mechanical alignment total knee arthroplasty

BackgroundTotal knee arthroplasty (TKA) demands precision in achieving optimal alignment and soft tissue balance, especially in cases of medial compartment osteoarthritis where the need for medial soft tissue release is critical yet challenging to ascertain.ObjectiveThis study aims to systematically investigate the relationship between preoperative data, initial knee conditions and the necessity for deep collateral ligament (MCL) release in adjusted mechanical alignment total knee arthroplasty.MethodsWe conducted a retrospective study involving 61 TKA patients who underwent adjusted mechanical alignment robotic-assisted procedures. Soft tissue release was carried out when clinically indicated. We collected and statistically analyzed patient demographics, initial knee conditions, and surgical details.ResultsAmong the patients, 52% required deep MCL release. Notably, patients without soft tissue release exhibited lower initial hip-knee-ankle (HKA) angles, reduced varus-valgus stress test angles, and a greater range of flexion. We identified a predictive threshold HKA angle of 6.250 degrees, demonstrating high sensitivity and specificity for determining the need for deep MCL release.ConclusionThis study underscores the significance of the initial HKA angle and varus-valgus stress tests in predicting deep MCL release during TKA. The established HKA angle threshold simplifies surgical decision-making, reducing the likelihood of unnecessary soft tissue release.

Determinants of pivot kinematics in posterior stabilized total knee arthroplasty

BackgroundRestoring medial knee pivot kinematics post-total knee arthroplasty is widely recognized to enhance patient satisfaction. Our study investigates the kinematics of patients who received posterior stabilized implants via robotic-arm assisted surgery, specifically analyzing effects of implant alignment and soft tissue balance on pivot location. MethodsTwelve high-functioning patients with unilateral posterior stabilizing knee implants underwent CT-guided robotic-arm assisted surgery. We then evaluated their knee kinematics using stereo radiography during gait, stair descent, lunge, seated knee extension and leg press. Femoral low-point condylar kinematics were used to calculate the transverse center of rotation, or pivot, using principal component analysis. Linear mixed effects regression was used to identify surgical parameters that influence pivot location across a flexion range. FindingsAcross all five activities a central pivot pattern emerged as the primary pivot location (40 %) followed by medial (25 %), no pivot (22 %) and lateral (14 %). Tibial medial resection depth and Tibial implant flexion-extension placement were significantly associated with shifting the pivot location laterally prior to cam-post engagement. Femoral implant external-internal implant placement, and medial compartment laxity in extension were significantly associated with shifting the pivot location laterally during the cam-post engagement, while femoral distal-lateral resection depth was associated with a medial shift. InterpretationCentral and medial pivot locations are predominant in patients with posterior stabilized total knee arthroplasty, facilitated by robotic-arm assisted surgery. Despite significant associations between surgical parameters such as tibial medial resection depth and lateral compartment laxity with medial pivot, these variables explained a small portion of the variability in pivot location. This suggests that while surgical precision influences pivot kinematics, individual patient factors may play a more critical role, suggesting a need for further research into patient-specific biomechanics to optimize post-surgical outcomes.

Effect of inverse kinematic alignment total knee arthroplasty on coronal alignment of the ankle joint in patients with varus knee deformity.

Varus or valgus knee deformities influence ankle coronal alignments. The impact of Total Knee Arthroplasty (TKA) on ankle joint alignment has not been entirely illustrated. Inverse Kinematic Alignment (iKA) is a surgical philosophy that aims to restore soft tissue balance, function, and native anatomy within validated boundaries to restore restrictive native kinematics. Therefore, this study aimed to investigate the postoperative association of patient-specific alignment on the coronal alignment of the ankle in patients with varus knee deformity who underwent iKA TKA. We hypothesized that greater preoperative varus malalignments would correlate with significant postoperative ankle coronal alignment changes. This retrospective study of a prospective collected cohort assessed patients who underwent imageless navigation assisted robotic TKA using a single implant design for primary osteoarthritis between January 2022 and August 2023. Preoperative and postoperative full-length standing anteroposterior X-ray imaging was used to measure Hip-Knee-Ankle (HKA), Tibial Plafond Inclination (TPI), Talar inclination (TI), and Tibiotalar Tilt (TTT) angles. Patients were subsequently divided into groups of neutral varus) < 10°) and severe varus (≥ 10°) according to the preoperative HKA angle. Significant changes in preoperative and postoperative HKA angles were found in the severe varus (14.5° vs. 6.4°, p < 0.001) group. Changes were also significant between preoperative and postoperative TPI and TI angles in the severe varus group; however, TTT did not reach statistical significance. Delta change from pre- to postoperative HKA was significantly higher for the severe varus group (8.1° vs. 0.8°, p < 0.019). Delta change of TPI, TI and TTT did not differ between groups. Coronal knee alignment after TKA affects coronal alignment of the ankle. iKA technique in TKA for varus knee deformity preserves or minimizes substantial coronal alignment changes of the ankle joint. These findings may add to the benefits reported for patient specific alignment TKA techniques. III.

Progress in Computer-Assisted Navigation for Total Knee Arthroplasty in Treating Knee Osteoarthritis with Extra-Articular Deformity.

Total knee arthroplasty (TKA) is a well-established treatment for end-stage knee osteoarthritis. However, in patients with concomitant extra-articular deformities, conventional TKA techniques may lead to unsatisfactory outcomes and higher complication rates. This review summarizes the application of navigated TKA for treating knee osteoarthritis with extra-articular deformities. The principles and potential benefits of computer navigation systems, including improved component alignment, soft tissue balancing, and restoration of mechanical axis, are discussed. Research studies demonstrate that navigated TKA can effectively correct deformities, relieve pain, and improve postoperative joint function and quality of life compared with conventional methods. The advantages of navigated TKA in terms of surgical precision, lower complication rates, and superior functional recovery are highlighted. Despite challenges like the learning curve and costs, navigated TKA is an increasingly indispensable tool for achieving satisfactory outcomes in TKA for knee osteoarthritis patients with extra-articular deformities.

Medial-pivot design does not provide superior clinical results compared to posterior-stabilized total knee arthroplasty despite kinematic differences during step-up and lunge activities: A prospective randomized controlled trial under medial tight soft tissue balance.

This study aimed to compare in vivo kinematics during weight-bearing daily activities and determine the relationship with clinical outcomes in patients undergoing total knee arthroplasty (TKA) with a medial-pivot (MP, Evolution™) versus a posterior-stabilized (PS, Persona®) design under constant conditions of intraoperative soft tissue balance. Forty patients undergoing MP or PS-TKA under similar conditions of soft tissue balance were enrolled in this prospective randomized controlled trial. Outcome measures included clinical knee society scores (KSS) and knee injury and osteoarthritis outcome scores (KOOS). A kinematic assessment was conducted while the participants performed lunge and step-up activities under fluoroscopic guidance. Eighteen patients in each arm completed 1-year follow-up and were included in the analysis. All patients experienced pain relief and satisfactory knee function postoperatively. In kinematics, in the MP arm, the medial femoral condyle remained consistent, whereas the lateral femoral condyle gradually shifted posteriorly with increasing knee flexion. Conversely, in the PS arm, paradoxical anterior movement of the medial femoral condyle accompanied the lateral pivot motion. During lunge and step-up activities, a medial-pivot motion was observed in 83% and 72% of knees in the MP arm, respectively, compared with 22% and 11% in the PS arm. Despite these differences in kinematics, there were no statistically significant differences in the KSS and KOOS between the two groups. Under weight-bearing conditions during flexion, knees that underwent Evolution™ MP-TKA did not show superior clinical results compared to Persona® PS-TKA, despite exhibiting in vivo kinematics closely resembling the normal in vivo pattern. Therapeutic studies-Level I.

'Extended' restricted kinematic alignment results in decreased residual medial gap tightness among osteoarthritic varus knees during robotic-assisted total knee arthroplasty.

The aims of this study were: 1) to describe extended restricted kinematic alignment (E-rKA), a novel alignment strategy during robotic-assisted total knee arthroplasty (RA-TKA); 2) to compare residual medial compartment tightness following virtual surgical planning during RA-TKA using mechanical alignment (MA) and E-rKA, in the same set of osteoarthritic varus knees; 3) to assess the requirement of soft-tissue releases during RA-TKA using E-rKA; and 4) to compare the accuracy of surgical plan execution between knees managed with adjustments in component positioning alone, and those which require additional soft-tissue releases. Patients who underwent RA-TKA between January and December 2022 for primary varus osteoarthritis were included. Safe boundaries for E-rKA were defined. Residual medial compartment tightness was compared following virtual surgical planning using E-rKA and MA, in the same set of knees. Soft-tissue releases were documented. Errors in postoperative alignment in relation to planned alignment were compared between patients who did (group A) and did not (group B) require soft-tissue releases. The use of E-rKA helped restore all knees within the predefined boundaries, with appropriate soft-tissue balancing. E-rKA compared with MA resulted in reduced residual medial tightness following surgical planning, in full extension (2.71 mm (SD 1.66) vs 5.16 mm (SD 3.10), respectively; p < 0.001), and 90° of flexion (2.52 mm (SD 1.63) vs 6.27 mm (SD 3.11), respectively; p < 0.001). Among the study population, 156 patients (78%) were managed with minor adjustments in component positioning alone, while 44 (22%) required additional soft-tissue releases. The mean errors in postoperative alignment were 0.53 mm and 0.26 mm among patients in group A and group B, respectively (p = 0.328). E-rKA is an effective and reproducible alignment strategy during RA-TKA, permitting a large proportion of patients to be managed without soft-tissue releases. The execution of minor alterations in component positioning within predefined multiplanar boundaries is a better starting point for gap management than soft-tissue releases.

Technology in Total Knee Arthroplasty in 2023

Over the past few decades, instrumentation and techniques for total knee arthroplasty have evolved from conventional manual tools to a wide range of technologies, including calibrated guides for accurate bone cuts and alignment, smart tools, dynamic intraoperative sensors for soft tissue balancing, patient-specific guides, computer navigation, and robotics. This review is intended to provide an overview of the latest advancements in total knee arthroplasty technology, address potential challenges and solutions related to the application of these technologies, and explore their limitations.

Comparative Analysis of Outcomes of Lateral Versus Medial Approach in the Total Knee Arthroplasty for Valgus Deformity: A Systematic Review and Meta-analysis.

Valgus knee deformity poses great challenges in total knee arthroplasty (TKA) and requires precision in balancing of soft tissue and implant component positioning. The surgical approach used for TKA has a determinantal impact on intraoperative soft tissue balancing, postoperative knee function, and complications. We executed a systematic review and meta-analysis of current literature, which included a maximum number of studies with quantitative analysis of all possible outcomes to substantiate the current evidence of the advantage of lateral versus medial approach in TKA for valgus knee deformity. We performed a meticulous primary electronic search across PubMed, Emabse, Scopus, and Cochrane Library databases, and looked for the comparative studies that evaluated the medial versus lateral approach in TKA for valgus knees. Statistical analyses were executed with RevMan-5.4.1. On the evaluation of four randomized controlled trials (RCTs), two prospective and five retrospective comparative studies, our analysis revealed a better functional outcome in terms of Knee Society Score [MD 2.24, 95% CI 0.42, 4.05; p = 0.02] with the medial approach. However, comparable results were observed for two approaches with regard to Knee Society Function [MD 0.69, 95% CI -1.77, 3.15; p = 0.58], knee flexion range of motion (ROM) [MD 3.30, 95% CI -1.34, 7.95; p = 0.16], overall complications [OR 0.60, 95% CI 0.27,1.34; p = 0.22], wound-related complications, infection, nerve injury, periprosthetic fracture, post-operative valgus, blood loss, duration of surgery, postoperative pain, and patellar tilt for TKA in valgus knee. Evidence from the currently available published data suggests that the lateral approach, compared to the medial approach in TKA for the valgus knee, does not show clear superiority.

Total knee arthroplasty after anterior cruciate ligament reconstruction: a narrative review.

Knee replacement following anterior cruciate ligament (ACL) reconstruction can be demanding due to altered anatomy, soft tissue scars, bone loss, extensor mechanism complications, and knee instability. This narrative review summarizes the strategies and approaches to managing operative challenges in total knee arthroplasty (TKA) following ACL reconstruction. Studies reporting outcomes of patients who underwent TKA after ACL reconstruction were retrieved and assessed to be included in this review that synthesizes the available evidence highlighting the pitfalls encountered during surgery, the intraoperative challenges posed by ligament balancing and exposure, and the leading role of modular and retained implants. TKA following ACL reconstruction has a high rate of intra-operative complications such as instability, bone loss, difficult exposure and demanding soft tissue balancing, representing a revision surgery rather than routine primary knee arthroplasty and a revision-oriented skill set and modular components are recommended to significantly optimize both surgical strategy and patient outcomes. With a rising incidence of ACL injuries and growing reconstructions, anticipating an increase in TKA procedures, this review aims to provide a call for rethinking clinical approaches to ensure effective and patient-centric care. This narrative review seems to indicate that TKA after ACL reconstruction should be considered as revision surgery and modular components should be used. However, future prospective and high-quality studies are required to better clarify risk factors and give strong recommendations for this complex surgery.

WITHDRAWN: Cadaveric Testing of a Novel Intraoperative Load Sensor for Soft-tissue balancing during Total Knee Replacements

AimThe aim of this research was to prove the functionality of a smart tibial sensor for use during total knee replacements to increase the clinical accuracy of a balanced knee. The accuracy of such device provides surgeons with an objective tool for load balancing in the knee, where currently the joint is balanced based on the surgeon’s ‘feel’ of a balanced knee. BackgroundLiterature surrounding the kinematics and tibiofemoral joint forces through the flexion arc coupled with qualitative feedback from an orthopaedic surgeon provided a basis for proving the functionality of the smart-sensor. MethodologyTwo full body cadavers underwent a cruciate-retaining total knee replacement using Zimmer’s Persona Knee System. Varying thicknesses adjusted the height of the tibial smart-sensor between 10mm-13mm in increments of 1mm. The contact points and loads were observed through the flexion arc (0°,45°, and 90°). ResultsThe results were between the literature surrounding both the compartmental forces and contact points throughout the range of motion. Moreover, qualitative feedback determined that the smart-sensor was robust and durable throughout its use in both cadavers demonstrating its potential as a reusable device. Minor adjustments to the graphical user interface would improve the ease of use for the surgical team. ConclusionThis sensor demonstrated the functionality of the smart-sensor through cadaveric testing in predicating both the load and location throughout a range of motion. Continued development of this sensor would provide surgeons with an accurate and robust tool for intraoperative joint balancing which could extend to all joints in the body for a more evidence based surgical procedure.

Early Clinical and Economic Outcomes for the VELYS Robotic-Assisted Solution Compared with Manual Instrumentation for Total Knee Arthroplasty.

Robotic-assisted total knee arthroplasty (TKA) has been developed to improve functional outcomes after TKA by increasing surgical precision of bone cuts and soft tissue balancing, thereby reducing outliers. The DePuy Synthes VELYS robotic-assisted solution (VRAS) is one of the latest entrants in the robotic TKA market. Currently, there is limited evidence investigating early patient and economic outcomes associated with the use of VRAS. The Premier Healthcare Database was analyzed to identify patients undergoing manual TKA with any implant system compared with a cohort of robotic-assisted TKAs using VRAS between September 1, 2021 and February 28, 2023. The primary outcome was all-cause and knee-related all-setting revisits within 90-day post-TKA. Secondary outcomes included number of inpatient revisits (readmission), operating room time, discharge status, and hospital costs. Baseline covariate differences between the two cohorts were balanced using fine stratification methodology and analyzed using generalized linear models. The cohorts included 866 VRAS and 128,643 manual TKAs that had 90-day follow-up data. The rates of both all-cause and knee-related all-setting follow-up visits (revisits) were significantly lower in the VRAS TKA cohort compared with the manual TKA cohort (13.86 vs. 17.19%; mean difference [MD]: -3.34 [95% confidence interval: -5.65 to -1.03] and 2.66 vs. 4.81%; MD: -2.15 [-3.23 to -1.08], respectively, p-value < 0.01) at 90-day follow-up. The incidence of knee-related inpatient readmission was also significantly lower (53%) for VRAS compared with manual TKA. There was no significant difference between total cost of care at 90-day follow-up between VRAS and manual TKA cases. On average, the operating room time was higher for VRAS compared with manual TKA (138 vs. 134 minutes). In addition, the discharge status and revision rates were similar between the cohorts. The use of VRAS for TKA is associated with lower follow-up visits and knee-related readmission rates in the first 90-day postoperatively. The total hospital cost was similar for both VRAS and manual TKA cohort while not accounting for the purchase of the robot.

Relationship between intra-operative joint gap and knee flexion angle after posterior-stabilized total knee arthroplasty

PurposeConflicting evidence exists about the appropriate intra-operative soft tissue balance in posterior-stabilized (PS) total knee arthroplasty (TKA). The purpose of this prospective observational study was to investigate the impact of intra-operative soft tissue balance on post-operative knee flexion angle. MethodsA single surgeon performed 164 TKAs using a single brand of PS prosthesis via the subvastus approach without using a pneumatic tourniquet. Intra-operative soft tissue balance was quantified as the gaps between the femoral component and tibial osteotomy surface with the knee flexed at 0°, 30°, 90°, and 120° with the patellofemoral joint reduced. Multiple regression analyses were employed to identify independent predictors of knee flexion angle 1 year after TKA. ResultThe pre-operative knee flexion angle and the gap difference between 120° and 0° flexion were positively correlated with knee flexion angle 1 year after TKA [β ​= ​0.37, 95% confidence interval (CI) 0.26–0.48, P ​< ​0.001; and β ​= ​1.09, 95% CI 0.04–2.14, P ​= ​0.042, respectively]. There was no correlation with knee flexion angle 1 year after TKA for the gap difference between 30° flexion and 0° flexion and between 90° flexion and 0° flexion. ConclusionsIntra-operative soft tissue balance at 120° flexion may affect the post-operative knee flexion angle in PS-TKA.

Intraoperative lateral laxity greater than 4° is associated with inferior functional improvement in posterior-stabilised total knee arthroplasty.

The study aimed to determine the impact of intraoperative lateral laxity at extension on clinical and functional outcomes 1 year after posterior-stabilised total knee arthroplasty (PS-TKA). In total, 91 varus-type osteoarthritic knees that underwent PS-TKA using the medial preservation gap technique were included. After the femoral trial component placement and patellofemoral joint reduction, the soft-tissue balance was assessed using an offset-type tensor with a 40-lb joint-distraction force. Patients were divided into the following three groups according to the intraoperative lateral laxity at extension (i.e., varus ligament balance) using the mean ± 1 standard deviation: Groups A, ≤0°; B, 0-4°; and C, >4°. The 2011 Knee Society Score (KSS) and 3-m timed up-and-go test (TUG) time 1-year postoperatively, and their improvements were compared among the groups. While significant improvements were observed in all subscales of the 2011 KSS and TUG post-TKA (p < 0.05), the improvement of functional activities and TUG time were significantly lower in Group C than in Group B (p < 0.05). However, no significant differences were observed in symptom improvement, patient satisfaction or patient expectation scores among the groups. An excessive lateral laxity (varus angle) >4° at extension was associated with lower improvement in functional ability 1-year postoperatively. Therefore, excessive intraoperative lateral laxity should be avoided in PS-TKA. Level IV.

Kinematic Alignment Achieves a More Balanced Total Knee Arthroplasty Than Mechanical Alignment among CPAK Type I Patients: A Simulation Study

Background: There is no consensus on whether mechanical alignment (MA) or kinematic alignment (KA) should be chosen for total knee arthroplasty (TKA) for coronal plane alignment of the knee (CPAK) Type I with a varus arithmetic HKA (aHKA) and apex distal joint line obliquity (JLO). The aim of this study was to investigate whether MA or KA is preferable for soft tissue balancing in TKA for this phenotype. Method: This prospective cohort study included 64 knees with CPAK Type I osteoarthritis that had undergone cruciate-retaining TKA. Using optical tracking software, we simulated implant placement in the Mako system before making the actual bone cut and compared the results between MA and KA. Extension balance (the difference between medial and lateral gaps in extension) and medial balance (the difference in medial gaps in flexion and extension) were examined. These gap differences within 2 mm were defined as good balance. Achievement of overall balance was defined as an attainment of good extension and medial balance. The incidence of balance in each patient was compared with an independent sample ratio test. Results: Compared with the MA group, the KA group achieved better soft tissue balance in extension balance (p &lt; 0.001). A total of 75% of the patients in the KA group achieved overall balance, which was greater than the 38% achieved in the MA group (p &lt; 0.001). Conclusions: In robot-assisted TKA for CPAK Type I osteoarthritis, KA achieved knee balance during extension without soft tissue release in a greater percentage of patients than MA.

FOREFOOT MORPHOTYPES IN CAVOVARUS FEET: A NOVEL CLASSIFICATION

BackgroundThe cavovarus foot is a complex 3-dimensional deformity. Although a multitude of techniques are described for its surgical management, few of these are evidence based or guided by classification systems. Surgical management involves realignment of the hindfoot and soft tissue balancing, followed by forefoot balancing. Our aim was to classify the pattern of residual forefoot deformities once the hindfoot is corrected, to guide forefoot correction.MethodsWe included 20 cavovarus feet from adult patients with Charcot-Marie-Tooth who underwent weightbearing CT (mean age 43.4 years, 14 males). Patients included had flexible deformities, with no previous surgery. Previous work established majority of rotational deformity in cavovarus feet occurs at the talonavicular joint, which is often reduced during surgery. Using specialised software (Bonelogic 2.1, Disior) a 3-dimensional, virtual model was created. Using data from normal feet as a guide, the talonavicular joint of the cavovarus feet was digitally reduced to a ‘normal’ position. Models of the corrected position were exported and geometrically analysed using Blender 3.6 to identify anatomical trends.ResultsWe identified 3 types of cavovarus forefoot morphotypes. Type 1 was seen in 13 cases (65%) and was defined as a foot where only the first metatarsal was relatively plantarflexed to the rest of the foot, with no significant residual adduction after talonavicular correction. Type 2 was seen in 4 cases (20%) and was defined as a foot where the second and first metatarsals were progressively plantarflexed, with no significant adduction. Type 3 was seen in 3 cases (15%) and was defined as a foot where the metatarsals were still adducted after talonavicular de-rotation.ConclusionWe classify 3 forefoot morphotypes in cavovarus feet. It is important to recognise and anticipate the residual forefoot deformities after hindfoot correction as different treatment strategies may be required for different morphotypes to achieve balanced correction.

Robotic-assisted differential total knee arthroplasty with patient-specific implants: surgical techniques and preliminary results

ObjectiveIn total knee arthroplasty (TKA), achieving soft-tissue balance while retaining acceptable lower limb alignment is sometimes difficult and may lead to patient dissatisfaction. Theoretically, patient-specific implants can bring great benefits, while the lack of precise surgical tools may hinder the improvement of outcomes. The objective of this study was to illustrate surgical techniques and evaluate kinematics and early clinical outcomes of robotic-assisted TKA using patient-specific implants.MethodsBased on preoperative CT scan, femoral and tibial components were 3D printed. Medial and lateral tibial liners were separate with different thicknesses, posterior slopes and conformity. TiRobot Recon Robot was used for surgery, and was armed with smart tools that quantify gap, force and femoral-tibial track. We collected data on demographics, intraoperative gap balance and femoral-tibial motion. In the follow-up, we evaluated the range of motion, Visual Analogue Scale (VAS), forgotten joint score (FJS), Knee injury and Osteoarthritis Outcome Score, Joint Replacement (KOOS, JR) score. Radiological data were also harvested.ResultsFifteen patients (17 knees) were enrolled with a mean age of 64.6 ± 6.4 (53–76) years. In 5 knees, we used symmetric tibial liners, the rest were asymmetric. After surgery, the average alignment was 1.6 ± 2.0 (-3–5) degrees varus. The average follow-up lasted 6.7 ± 4.2 (1–14) months. The mean visual analogue scale was 0.8 ± 0.7 (0–2), FJS was 62.4 ± 25.3 (0–87), KOOS was 86.5 ± 9.4 (57–97). 11 patients were “very satisfied”, 3 were “satisfied" with the result, and one patient was neutral due to restricted extension and unsatisfactory rehabilitation at five months’ follow-up.ConclusionsWith patient-specific implants and robotics, TKA could be performed by a mathematical way, which was dubbed a “differential” TKA. Intraoperative kinematics was excellent in terms of gap-force balancing and femoral-tibial relative motion. Preliminary clinical outcomes were overall satisfactory.

Short-term results of soft tissue balance obtained with 'manual gap balancing' in varus knees; a prospective study supported by gait analysis

Aim: The aim of this study was to investigate the contribution of medial ligament release using the manual gap balance method in patients with varus deformity to alignment and functional outcomes. Materials and Methods: The study included 14 female and 8 male patients who underwent total knee arthroplasty. Telemetric radiographs of the lower extremities and valgus stress radiographs of the knees to be operated on were taken for each patient one day before and 1.5 months after the operation. The functional evaluation of patients was conducted using the HSS (Hospital for Special Surgery, 1970) scoring system. Simultaneously, gait analyses were conducted. The patients were divided into groups based on their stress radiographs. Results: The mean valgus angle in postoperative static radiographs was 2.5 degrees. A statistically significant change in rotational deformity was observed in both swing and stance phases after surgery compared to preoperative values. Improvement in coronal plane varus knees was statistically significant. No significant change was found in the flexion-extension angles of sagittal plane kinematics. It was found that there was a statistically significant difference in the data for single support, double support, and stance percentage (p