Intraoperative Soft Tissue Balance Research Articles

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.

Medial Soft Tissue-Preserving Technique Impact on Sagittal Stability in Bi-cruciate Stabilized Total Knee Arthroplasty.

Sagittal stability in total knee arthroplasty is achieved through complex processes enabled by prosthetic design and intraoperative soft tissue balancing. This study investigated the effects of preserving medial soft tissue on sagittal stability in bicruciate stabilized total knee arthroplasty (BCS TKA). This retrospective study included 110 patients who underwent primary BCS TKA. The patients were divided into two groups: 44 TKAs were performed releasing medial soft tissue (CON group), and 66 TKAs were performed preserving medial soft tissue (MP group). We assessed joint laxity using tensor device and anteroposterior translation immediately after surgery using the arthrometer at 30° knee flexion. Propensity score matching (PSM) was performed according to preoperative demographic and intraoperative medial joint laxity, and further comparisons between the two groups were performed. After PSM analysis, medial joint laxity in the mid-flexion range tended to be smaller in the MP group than in the CONT group, with a significant difference at 60 degrees (CON group: - 0.2 ± 0.9mm, MP group: 0.8 ± 1.3mm, P < 0.05). Anteroposterior translation was significantly different between the two cohorts (CON group: 11.6 ± 2.5mm, MP group: 8.0 ± 3.1mm, P < 0.001). This study demonstrated the effects of preserving medial soft tissue on postoperative sagittal stability in BCS TKA. We concluded that this surgical procedure enhances postoperative sagittal stability in the mid-flexion range in BCS TKA.

Ground kinematically aligned total knee arthroplasty: new personalized technique which enables a stable knee with deep flexion

PurposeThis study aimed to evaluate kinematically aligned total knee arthroplasty (KA-TKA) targeting the neutral ground mechanical axis (MA) (hip-to-calcaneus axis), the line from the hip centre to the bottom of the calcaneus, (ground KA-TKA) in terms of its comparison with tibia-restricted modified KA-TKA (modified KA-TKA).MethodsThis retrospective cohort study included 106 consecutive patients who underwent unilateral KA-TKA for varus osteoarthritis (OA) (60 modified KA-TKAs and 46 ground KA-TKAs). After 1:1 propensity score matching, 60 patients (30 pairs) were matched between the groups with comparable demographic data. The hip-knee-ankle (HKA) angle, coronal femoral component alignment (FCA), and coronal tibial component alignment (TCA) were compared between groups. Intraoperative soft tissue balance, including the joint component gap and varus/valgus balance, was also compared between the groups. One year postoperatively, the clinical outcomes, including the range of motion and 2011 Knee Society Score, were compared between groups.ResultsThe HKA angle and FCA/TCA were not significantly different between groups. Whereas the varus/valgus balance showed no significant differences between groups, smaller joint component gaps were found throughout the range of motion in the ground KA-TKA group than in the modified KA-TKA group. Despite no difference in clinical scores between groups, a significantly deeper postoperative flexion angle was achieved in the ground KA-TKA group than in the modified KA-TKA group (p < 0.05).ConclusionTargeting neutral ground MA in KA-TKA for patients with varus OA has the potential to provide a better flexion angle with stable intraoperative soft tissue balance.

Prosthetic orientation, limb alignment, and soft tissue balance with bi-cruciate stabilized total knee arthroplasty: a comparison between the handheld robot and conventional techniques

PurposeThis study aimed to examine the prosthetic orientations, limb alignment, intraoperative soft tissue balance, and early clinical outcomes associated with the use of the relatively new handheld robot technique compared to those associated with the use of the conventional alignment guide for bi-cruciate stabilized total knee arthroplasty (TKA).MethodsThis retrospective cohort study compared the prosthetic orientation and limb alignment of 35 patients who underwent TKA using robotic assistance (robot group) with those of patients who underwent TKA using a conventional alignment guide (control group). The coronal femoral component alignment (FCA), coronal tibial component alignment (TCA), and the hip-knee-ankle (HKA) angle were compared between groups. Intraoperative soft tissue balance, including the joint component gap and varus/valgus balance assessed by an offset-type tensor, were also compared between groups. One year postoperatively, the clinical outcomes, including the range of motion and 2011 Knee Society Score (KSS), were compared between groups.ResultsThe HKA angle and FCA were 0.1° varus and 0.1° varus, respectively, in the robot group and 1.3° varus and 1.3° varus, respectively, in the control group. The difference in the HKA angle and the FCA, but not the TCA, between groups was statistically significant (p < 0.05). The intraoperative soft tissue balance showed more stable joint component gaps and varus/valgus balances throughout the range of motion in the robot group than in the control group. Clinical outcomes of the robot group showed superior 2011 KSS subscales compared to those of the control group.ConclusionThe accuracy of the implantations and stable soft tissue balance in the robot group were superior to those of the control group. The robot group also had superior patient-reported scores for early clinical outcomes.

Functional knee apparatus for the evaluation of ligamentous tensions on contact loads

BackgroundSoft tissue balancing is integral in providing stability following total knee arthroplasty (TKA). Although intraoperative contact load sensors are providing insights into the effects of soft tissue balancing, there is still a lack of understanding of the relationship between the knee’s ligamentous tensions and joint surface contact loads. This study reports on the development of a multifunctional testing apparatus that can quantify the effects of ligamentous tension on joint contact loads in a controlled repeatable environment. MethodsThe functional knee apparatus was constructed to act as an anatomical substitute for the benchtop assessment of intraoperative soft tissue balancing. The system was calibrated through reproduction of results from a cadaveric study that employed intraoperative load sensors. Experimentation was then conducted to quantify the effects of tensile pretension variation on measured contact loads throughout the full range of flexion. ResultsA linear relationship between the ligamentous tensions and contact loads was observed, with ligaments contributing to 74–80% of the measured contact loads. Ligamentous tensions could be approximated from measured contact loads to within ± 23 N. ConclusionThe proposed apparatus can prove to be a valuable tool in the continued exploration of currently undocumented effects (e.g. surgical alteration) in soft tissue balancing. In addition to quantifying the relationship between ligamentous tensions and joint contact loads, soft tissue loading conditions where bicondylar contact was lost (i.e. known sign of kinematic instability) were identified. As a corollary, this system may be able to provide insights on soft tissue balancing standards predictive of patient outcomes.

Can mobile-bearing unicompartmental knee arthroplasty achieve natural gap-balancing? An observational study with a novel pressure sensor

BackgroundMobile-bearing unicompartmental knee arthroplasty (MB-UKA) is an effective treatment for anteromedial knee osteoarthritis. Meticulous intraoperative soft tissue balancing remains challenging yet consequential for a successful operation. Currently, surgeons rely mostly on their experience during soft tissue balancing, yielding unreproducible results. The purpose of this study was to quantified measure the soft tissue tension of medial compartment and determine if an optimal "target" tension values with the natural state exists.MethodsThis was an observational study of 24 consecutive patients. All 30 UKAs were performed by a single surgeon. The piezoresistive sensor was custom designed to fit in the medial compartment gap. Contact pressures were measured at 5 angular positions of the knee intraoperatively: 0°, 20°, 45°, 90°, and 110° of flexion. The change in pressure from extension (20° position) and flexion (110° position) was also calculated (E-FPD). Data on age, sex, body mass index, operative side, and bearing size were collected. Outcome measures were measured at baseline and at the 6-month postoperative follow-up; Oxford Knee Score, visual analog scale score, and range of motion were compared to evaluate clinical outcomes.ResultsThere was a significant improvement in patients in all measured outcomes at 6 months from baseline (P < 0.05). The E-FPD of 14.9 N (8.9, 24.6) was indicative of appropriate soft tissue balancing throughout the functional range of knee motion. Of 30 knees, 22 were 3-mm bearing and 8 were 4- or 5-mm bearing. The pressure data of the 3-mm bearing group was larger than that of the non-3-mm bearing group for each knee flexion degree, but the difference was not statistically significant (P > 0.05).ConclusionsObjective data from sensor output may assist surgeons in decreasing loading variability during MB-UKA. The data suggested that MB-UKA could not accurately restore soft tissue tension to the natural state, which was related to the inability of MB-UKA surgical instruments to fine adjust the bone cut and soft tissue release.Study registrationChinese Clinical Trial Registry (http://www.chictr.org.cn): ChiCTR1900024146.

The Effect of Prosthesis Type on Intraoperative Soft-Tissue Balance and Clinical Outcomes in Modified Kinematically Aligned Cruciate-Retaining Total Knee Arthroplasty.

Kinematically aligned total knee arthroplasty (KA-TKA) has gained interest for achieving more favorable clinical outcomes than mechanically aligned TKA. One of the advantages of KA-TKA is reported to be an easy acquisition of intraoperative soft-tissue balance without excessive medial release for varus osteoarthritis. However, we hypothesized that the prosthesis type affects intraoperative soft-tissue balance even in the KA-TKA. The present study aimed to compare intraoperative soft-tissue balance and clinical outcomes of KA-TKAs using single-radius (SR) or multiradius (MR) prostheses. AND METHODS: Consecutive 70 cruciate-retaining modified KA-TKAs (31 SR and 39 MR) were performed in patients with varus-type osteoarthritis using a navigation system. Intraoperative soft-tissue balance including joint component gap and varus/valgus balance was measured with femoral component placement and patellofemoral joint reduction throughout the range of motion using offset-type tensor and compared between the two groups. Two years postoperatively, the range of motion and 2011 Knee Society Scores were compared between the two groups. Joint component gaps showed no significant differences between the two groups from 0 to 30 degrees of flexion. However, during 60 to 120 degrees of flexion, joint component gaps of SR group showed significantly larger values than those of MR group (p < 0.05). There were no significant differences in varus/valgus balance throughout the range of motion between the two groups. The postoperative clinical outcomes showed no significant differences between the two groups. Despite no difference in clinical outcomes, joint component gap showed different patterns due to the prosthesis type in modified KA-TKAs.

STUDY OF THE CLINICO-RADIOLOGICAL OUTCOME OF PCL RETAINING TOTAL KNEE ARTHROPLASTY IN SEVERE VARUS DEFORMITY: A PROSPECTIVE OBSERVATIONAL STUDY.

Introduction: The role of the posterior cruciate ligament (PCL) in total knee arthroplasty (TKA) has been widely discussed in the orthopedic literature. It has been suggested that PCLretaining can produce femoral rollback, which increases the range of exion and prevents posterior translation. This in effect, reduces loosening and excessive polyethylene wear by decreasing the shear stresses at the xation surfaces. With consideration proper selection of patients, adequate attention to surgical technique and asepsis, proper Intra-operative soft tissue balancing, correct alignment of prosthesis and postoperative rehabilitation of patients, cruciate retaining total knee replacement has yielded excellent results Aim: The aim of this prospective study is to evaluate the clinic-radiological outcome of PCL retaining total knee arthroplasty in severe varus deformity Materials and Methods: This is a prospective study in which patients were randomly selected, and PCL retaining surgery was done for those knees with severe varus deformity and assessed the functional outcome using functional knee scores and oxford knee score and WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) questionnaires during the period between July 2016 to June 2018. Conclusion: PCL-retaining total knee arthroplasty appears to provide better range of motion and stair-climbing ability similar to anatomical knee.

Comparison of the joint laxity of total knee arthroplasty evaluated by the distraction force and the varus–valgus force

BackgroundComponent gap (CG) measurement help surgeons evaluate intraoperative soft-tissue balance. One technique is measuring the CG using tensioner devices with distraction force. Another is to evaluate the laxity under a varus–valgus force using navigation or robotics. The aim was to compare the JL evaluated by CG and varus–valgus force between the different types of total knee arthroplasties. MethodsForty-three bi-cruciate stabilized (BCS) knees and 33 bi-cruciate retaining (BCR) knees were included. After bone resection and soft tissue balancing, the CG was measured and after the final implantation and capsule closure, JL under a maximum varus–valgus stress was recorded with navigation. JL evaluated by the CG (JLCG) was defined as CG minus selected thickness of the tibial component and JL under varus–valgus force (JLVV) was defined as difference between varus–valgus angles without stress and maximum varus–valgus angles under varus–valgus force. The evaluations were performed at flexions of 10°, 30°, 60° and 90°. ResultsAlthough JLCGs of lateral compartment of BCS were larger than those of BCR, no difference was found between JLVVs of BCS and BCR. Although JLCGs of lateral compartment did not change at each knee flexion angle in both BCS and BCR, JLVVs of lateral compartment increased by 3° from 10° to 90° knee flexion. ConclusionJLVVs of BCS and BCR were equivalent, whereas BCS showed larger JLCGs of lateral compartment. JLVVs of lateral compartment increased by 3° in the range from 10° to 90° knee flexion whereas JLCGs remained stable.

Both intraoperative medial and lateral soft tissue balances influence intraoperative rotational knee kinematics in bi-cruciate stabilized total knee arthroplasty: A retrospective investigation

BackgroundTibial internal rotation following total knee arthroplasty (TKA) is important in achieving favorable postoperative clinical outcomes. Studies have reported the effect of intraoperative soft tissue balance on tibial internal rotation in conventional TKA, no studies have evaluated the effects of soft tissue balance at medial or lateral compartments separately on tibial internal rotation in bi-cruciate stabilized (BCS) TKA. The purpose of this study was to clarify the relationship between medial or lateral component gaps and rotational knee kinematics in BCS TKA.MethodsOne hundred fifty-eight knees that underwent BCS TKA were included in this study. The intraoperative medial and lateral joint laxities which was defined as the value of component gap minus the thickness of the tibial component were firstly divided into two groups, respectively: Group M-stable (medial joint laxity, ≤ 2 mm) or Group M-loose (medial joint laxity, ≥ 3 mm) and Group L-stable (lateral joint laxity, ≤ 3 mm) or Group L-loose (lateral joint laxity, ≥ 4 mm). And finally, the knees enrolled in this study were divided into four groups based on the combination of Group M and Group L: Group A (M-stable and L-stable), Group B (M-stable and L-loose), Group C (M-loose and L-stable), and Group D (M-loose and L-loose). The intraoperative rotational knee kinematics were compared between the four Groups at 0°, 30°, 60°, and 90° flexion, respectively.ResultsThe rotational angular difference between 0° flexion and maximum flexion in Group B at 30° flexion was significantly larger than that in Group A at 30° flexion (*p < 0.05). The rotational angular difference between 30° flexion and maximum flexion in Group B at 30° flexion was significantly larger than that in Group D at 30° flexion (*p < 0.05). The rotational angular differences between 30° or 90° flexion and maximum flexion in Group B at 60° flexion were significantly larger than those in Group A at 60° flexion (*p < 0.05).ConclusionSurgeons should pay attention to the importance of medial joint stability at midflexion and lateral joint laxities at midflexion and 90° flexion on a good tibial internal rotation in BCS TKA.

Preoperative varus deformity of the knee affects the intraoperative joint gap in unicompartmental knee arthroplasty

BackgroundIt is generally believed that contraction of the soft tissue structures on the medial side may occur in the knee with severe varus deformity. However, the relationship between the severity of varus deformity of the knee and the intraoperative soft tissue balance in unicompartmental knee arthroplasty (UKA) has not been well reported thus far. MethodsOne hundred and three consecutive medial UKAs were enrolled. After the femoral trial prosthesis was placed, the component gap was measured at 10° (extension) and 120° (flexion) of flexion using a UKA tensor. The pre-osteotomy gap was then calculated from the thickness of the bone cut. Paired Student’s t-test was used to compare the component gap, as well as the pre-osteotomy gap, in extension and those in flexion. The relationship between the preoperative Hip-Knee-Ankle (HKA) angle and the pre-osteotomy gap was analysed using Pearson’s correlation coefficient and simple linear regression analysis. ResultsThe component gap in extension was significantly smaller than that in flexion while the pre-osteotomy gap in extension was significantly wider than that in flexion. There was a positive correlation between the severity of varus deformation in preoperative knee and the pre-osteotomy gap in extension, while there was no correlation between the preoperative HKA angle and the pre-osteotomy gap in flexion. ConclusionsThe tension of the medial tightness does not correlate with the degree of preoperative varus deformity in UKA.

Rotational Soft-Tissue Balance Is Highly Correlated with Rotational Kinematics in Total Knee Arthroplasty.

Recovery of normal knee kinematics is critical for improving functional outcomes and patient satisfaction after total knee arthroplasty (TKA). The kinematics pattern after TKA varies from case to case, and it remains unclear how to reproduce normal knee kinematics. The present study aimed to evaluate rotational knee kinematics and soft-tissue balance using a navigation system and to assess the influence of intraoperative soft-tissue balance on the rotational knee kinematics. We evaluated 81 osteoarthritic knees treated with TKA using a posterior stabilized (50 knees) or cruciate retaining (31 knees) prosthesis. Rotational kinematics were assessed at 0, 30, 45, 60, and 90 degrees flexion angles by using a computer-assisted navigation system. Correlation between femorotibial rotational position and measured soft tissue balance was assessed by using Spearman's rank correlation coefficient. Rotational soft-tissue balance (the median angle of rotational stress) was significantly correlated with rotational kinematics (rotational axis of the femur relative to the tibia throughout the range of motion) at all measured angles after TKA. The correlation coefficients between the median angle of rotational stress and rotational kinematics were 0.97, 0.80, 0.74, 0.71, and 0.70 at 0, 30, 45, 60, and 90 degrees of flexion, respectively (p-values <0.0001 in all measured angles). The correlation coefficient increased as the knee approached full extension. Our findings suggest that soft-tissue balance is a key factor for rotational kinematics, following both cruciate-retaining and posterior-stabilized TKA.

Functional alignment achieves soft-tissue balance in total knee arthroplasty as measured with quantitative sensor-guided technology.

Total knee arthroplasty (TKA) using functional alignment aims to implant the components with minimal compromise of the soft-tissue envelope by restoring the plane and obliquity of the non-arthritic joint. The objective of this study was to determine the effect of TKA with functional alignment on mediolateral soft-tissue balance as assessed using intraoperative sensor-guided technology. This prospective study included 30 consecutive patients undergoing robotic-assisted TKA using the Stryker PS Triathlon implant with functional alignment. Intraoperative soft-tissue balance was assessed using sensor-guided technology after definitive component implantation; soft-tissue balance was defined as intercompartmental pressure difference (ICPD) of < 15 psi. Medial and lateral compartment pressures were recorded at 10°, 45°, and 90° of knee flexion. This study included 18 females (60%) and 12 males (40%) with a mean age of 65.2 years (SD 9.3). Mean preoperative hip-knee-ankle deformity was 6.3° varus (SD 2.7°). TKA with functional alignment achieved balanced medial and lateral compartment pressures at 10° (25.0 psi (SD 6.1) vs 23.1 psi (SD 6.7), respectively; p = 0.140), 45° (21.4 psi (SD 5.9) vs 20.6 psi (SD 5.9), respectively; p = 0.510), and 90° (21.2 psi (SD 7.1) vs 21.6 psi (SD 9.0), respectively; p = 0.800) of knee flexion. Mean ICPD was 6.1 psi (SD 4.5; 0 to 14) at 10°, 5.4 psi (SD 3.9; 0 to 12) at 45°, and 4.9 psi (SD 4.45; 0 to 15) at 90° of knee flexion. Mean postoperative limb alignment was 2.2° varus (SD 1.0°). TKA using the functional alignment achieves balanced mediolateral soft-tissue tension through the arc of knee flexion as assessed using intraoperative pressure-sensor technology. Further clinical trials are required to determine if TKA with functional alignment translates to improvements in patient satisfaction and outcomes compared to conventional alignment techniques. Cite this article: Bone Joint J2021;103-B(3):507-514.

The medial gap is a reliable indicator for intraoperative soft tissue balancing in posterior-stabilized total knee arthroplasty

BackgroundAppropriate soft tissue balance and accurate alignment are important for successful total knee arthroplasty (TKA). However, the optimal technique for establishing and measuring soft tissue balancing remains unclear. The aim of this study was to analyze the intraoperative medial and lateral gap pattern using digital knee balancer in posterior-stabilized (PS) TKA. MethodsThis study involved 55 patients with medial osteoarthritis who underwent a primary TKA using an image-free navigation system. The extension gap and the flexion gap at 90° knee flexion were assessed using an offset seesaw-type digital balancer. Continuous joint distraction force from 10 lb to 60 lb was applied. Medial gap, lateral gap, and varus angle were measured. ResultsThe medial bone gap difference between extension and flexion was constant regardless of the distraction force from 20 lb to 60 lb. The lateral bone gap was significantly greater than the medial bone gap in extension and flexion from 30 lb to 60 lb (P < 0.05). The varus angle changed depending on the distraction force, especially in flexion. The varus angle in flexion was significantly greater than that in extension from 40 lb to 60 lb (P < 0.05). ConclusionsThe medial bone gap is a reliable indicator unaffected by the distraction force during surgery and is useful for adjusting the medial gap in extension and flexion appropriately to ensure medial stability in PS-TKA. The digital knee balancer and navigation system support both precise gap assessment and surgery.

Long-Term Follow up of Correction of Moderate to Severe Coronal Plane Deformity With the Star Ankle Prosthesis

Background: Addressing coronal plane deformity when performing a total ankle arthroplasty (TAA) remains a topic of controversy. While surgeons have become bolder in correcting deformity, long-term follow-up is sparse regarding maintenance of correction and viability of the prosthesis. The purpose of this study is to assess the long-term follow up of the correction of moderate to severe coronal plane deformity with the use of a mobile bearing prosthesis. Methods: Out of a consecutive series of 130 patients who underwent TAA between 2000 and 2009, 43 patients (44 ankles) had at least 100 of tibiotalar coronal plane deformity, with 25 having between 100 and 200 of deformity and 18 having greater than 200. Average age at time of the index surgery was 66 yrs (range 41-79). Initial deformity was 17.90 (range 10-290) in the entire cohort. All patients underwent intraarticular deformity correction with intraoperative soft-tissue balancing as indicated utilizing the STAR prosthesis. Patients requiring realignment osteotomies were performed in a staged fashion prior to undergoing TAA. Results: Seven patients (16%) were available for long-term follow up (avg 13 yrs; range 9-16 yrs) with retention of the original prosthesis, two of which had greater than 200 of initial deformity. Average final tibiotalar deformity was 4.90, with a mean correction of 130 (p = 0.0001). No additional procedures related to the prosthesis were performed. Eleven patients (12 ankles) were deceased at the time of the study due to unrelated conditions. Of the original cohort, five were deemed failures (2 converted to arthrodesis; 2 underwent component revision; 1 polyethylene fracture) and excluded from long-term follow up. The remaining 20 patients were lost to follow-up, had declined or were unable to participate due to health status. Conclusion: While the low follow-up rate limits the overall generalizability of the results, enduring correction of moderate and severe coronal plane deformity with a mobile bearing prosthesis can be achieved in a cohort of patients traditionally regarded as high-risk. One must be cautious when discussing with patients the utilization of TAA in the setting of moderate and severe coronal plane deformity given the risk of failure. However, provided a well-balanced ankle can be achieved intraoperatively, long-term mobile bearing prosthesis survivorship is achievable.

Long-Term Follow up of Correction of Moderate to Severe Deformity with the STAR Ankle Prosthesis

Category:Ankle ArthritisIntroduction/Purpose:Addressing coronal plane deformity when performing a total ankle arthroplasty (TAA) remains a topic of controversy. While surgeons have become bolder in correcting deformity, long-term follow-up is sparse regarding maintenance of correction and viability of the prosthesis. The purpose of this study is to assess the long-term follow up of the correction of moderate to severe coronal plane deformity with the use of a mobile bearing prosthesis.Methods:Out of a consecutive series of 130 patients who underwent TAA between 2000 and 2009, 43 patients (44 ankles) had at least 100 of tibiotalar coronal plane deformity, with 25 having between 100 and 200 of deformity and 18 having greater than 200. Average age at time of the index surgery was 66 yrs (range 41-79). Initial deformity was 17.90 (range 10-290) in the entire cohort. All patients underwent intraarticular deformity correction with intraoperative soft-tissue balancing as indicated utilizing the STAR prosthesis. Patients requiring realignment osteotomies were performed in a staged fashion prior to undergoing TAA.Results:Seven patients (16%) were available for long-term follow up (avg 13 yrs; range 9-16 yrs) with retention of the original prosthesis, two of which had greater than 200 of initial deformity. Average final tibiotalar deformity was 4.90, with a mean correction of 130(p=0.0001). No additional procedures related to the prosthesis were performed. Eleven patients (12 ankles) were deceased at the time of the study due to unrelated conditions. Of the original cohort, five were deemed failures (2 converted to arthrodesis; 2 underwent component revision; 1 polyethylene fracture) and excluded from long-term follow up. The remaining 20 patients were lost to follow-up, had declined or were unable to participate due to health status.Conclusion:While the low follow-up rate limits the overall generalizability of the results, enduring correction of moderate and severe coronal plane deformity with a mobile bearing prosthesis can be achieved in a cohort of patients traditionally regarded as high-risk. One must be cautious when discussing with patients the utilization of TAA in the setting of moderate and severe coronal plane deformity given the risk of failure. However, provided a well-balanced ankle can be achieved intraoperatively, long-term mobile bearing prosthesis survivorship is achievable.

Comparison of intraoperative soft tissue balance measurement between two tensor systems in total knee arthroplasty

BackgroundDifferences in measurement outcomes using different tensors in total knee arthroplasty (TKA) remain unknown. This study aimed to compare intraoperative soft tissue balance between two measurement systems in TKA. MethodsThis study included 24 cruciate-retaining (CR) and 27 posterior-stabilized (PS) TKAs for varus-type osteoarthritis. All TKAs were performed with the measured resection technique. Intraoperative soft tissue balance was assessed with femoral component placement and patellofemoral joint reduction throughout the range of motion. Measurements were performed using the Offset Repo-Tensor (Zimmer) and Ligament Sensor Tensor (Depuy). Joint component gaps and varus/valgus ligament balance were compared statistically in CR and PS TKAs. ResultsJoint component gaps with the Offset Repo-Tensor were significantly larger at 0°, 10°, 30°, and 60° of knee flexion in CR TKA and at all knee flexion angles, except 0° and 135°, in PS TKA than those with the Ligament Sensor Tensor (P < .05). Varus balance with the Offset Repo-Tensor was significantly larger at 0°, 10°, and 30° of knee flexion in CR TKA and at 10°, 30°, 60°, 90°, and 120° of knee flexion in PS TKA than that with the Ligament Sensor Tensor (P < .05). ConclusionSurgeons should consider the discrepancy in assessing intraoperative soft tissue balance depending on the tensor used. The Ligament Sensor Tensor tended to underestimate soft tissue balance in CR and PS TKAs compared with the Offset Repo-Tensor, especially in PS TKA. Thus, surgeons should know the difference in values between the offset-type tensor with consistent distraction force and a spring-loaded tensor.

Long-Term Follow up of Correction of Moderate to Severe Coronal Plane Deformity With the Star Ankle Prosthesis

Background: Addressing coronal plane deformity when performing a total ankle arthroplasty (TAA) remains a topic of controversy. While surgeons have become bolder in correcting deformity, long-term follow-up is sparse regarding maintenance of correction and viability of the prosthesis. The purpose of this study is to assess the long-term follow up of the correction of moderate to severe coronal plane deformity with the use of a mobile bearing prosthesis. Methods: Out of a consecutive series of 130 patients who underwent TAA between 2000 and 2009, 43 patients (44 ankles) had at least 100 of tibiotalar coronal plane deformity, with 25 having between 100 and 200 of deformity and 18 having greater than 200. Average age at time of the index surgery was 66 yrs (range 41-79). Initial deformity was 17.90 (range 10-290) in the entire cohort. All patients underwent intraarticular deformity correction with intraoperative soft-tissue balancing as indicated utilizing the STAR prosthesis. Patients requiring realignment osteotomies were performed in a staged fashion prior to undergoing TAA. Results: Seven patients (16%) were available for long-term follow up (avg 13 yrs; range 9-16 yrs) with retention of the original prosthesis, two of which had greater than 200 of initial deformity. Average final tibiotalar deformity was 4.90, with a mean correction of 130 (p = 0.0001). No additional procedures related to the prosthesis were performed. Eleven patients (12 ankles) were deceased at the time of the study due to unrelated conditions. Of the original cohort, five were deemed failures (2 converted to arthrodesis; 2 underwent component revision; 1 polyethylene fracture) and excluded from long-term follow up. The remaining 20 patients were lost to follow-up, had declined or were unable to participate due to health status. Conclusion: While the low follow-up rate limits the overall generalizability of the results, enduring correction of moderate and severe coronal plane deformity with a mobile bearing prosthesis can be achieved in a cohort of patients traditionally regarded as high-risk. One must be cautious when discussing with patients the utilization of TAA in the setting of moderate and severe coronal plane deformity given the risk of failure. However, provided a well-balanced ankle can be achieved intraoperatively, long-term mobile bearing prosthesis survivorship is achievable.

Effect of femoral component rotation 0° to intraoperative soft tissue balance in cruciate retaining TKA

Effect of femoral component rotation 0° to intraoperative soft tissue balance in cruciate retaining TKA

Influence of Narrow Femoral Implants on Intraoperative Soft Tissue Balance in Posterior-Stabilized Total Knee Arthroplasty

BackgroundNarrow femoral implants were developed to improve fit and prevent overhang in primary total knee arthroplasty (TKA). We compared intraoperative soft tissue balance between standard and narrow implants in posterior-stabilized (PS) TKA. MethodsWe enrolled 30 consecutive patients with varus osteoarthritis undergoing PS TKA using an image-free navigation system. Standard and narrow femoral trial implants were inserted, and their soft tissue balance was measured. Subgroup analysis, based on the actual implanted femoral implant, was performed to assess the influence of narrow implants on soft tissue balance. ResultsNarrow trial group had significantly larger joint component gaps than standard trial group at all measured flexion angles, except at 60° (P < .05). For the standard implant cohort, narrow trial group had significantly larger joint component gaps than standard trial group at 30°, 120°, and 135° flexion (P < .05). For the narrow implant cohort, narrow trial group had significantly larger joint component gaps than standard trial group at all measured flexion angles, except at 0° and 60° (P < .05). Narrow trial group had significantly larger varus ligament balance than standard trial group at 45° and 60° flexion (P < .05). The varus angles for standard implants were comparable between groups; however, narrow trial group had significantly larger varus angles for narrow implants than standard trial group at 45°, 60°, and 120° flexion (P < .05). ConclusionThe medial-lateral dimension and volume of the femoral component may influence intraoperative soft tissue balance in PS TKA. The effects may be greater when narrow implants are selected to avoid component overhang.