Joint Line Elevation Research Articles

Influence of Joint Line Level on Clinical Outcomes and Range of Motion in Total Ankle Arthroplasty.

Ankle arthritis leads to an elevated joint line compared to the nonarthritic ankle, as measured by the "joint line height ratio" (JLHR). Previous work has shown that the JLHR may remain elevated after total ankle arthroplasty (TAA). However, the clinical impact of this has yet to be determined. This study assessed the correlation between postoperative JLHR, post-TAA range of motion (ROM), and 1-year Patient-Reported Outcome Measurement Information System (PROMIS) scores. A retrospective review of 150 patients who underwent primary TAA was performed. Preoperative and postoperative JLHR, as well as postoperative dorsiflexion, plantarflexion, and total ROM, was calculated on weightbearing radiographs at a minimum of 1-year follow-up. Correlation between JLHR, post-TAA ROM, and 1-year PROMIS scores was investigated using Pearson correlation and multiple linear regression models. Interobserver reliability for the JLHR was also calculated. Interobserver reliability for the JLHR was excellent (r = 0.98). Mean (SD) JLHR changed from 1.66 (0.45) to 1.55 (0.26) after TAA (P < .001), indicating that the joint line was lowered after TAA. An elevated joint line was correlated with decreased post-TAA dorsiflexion (r = -0.26, P < .001), total ROM (r = -0.18, P = .025), and worse 1-year PROMIS physical function (r = -0.22, P = .046), pain intensity (r = 0.22, P = .042), and pain interference (r = 0.29, P = .007). There was no correlation between the JLHR and post-TAA plantarflexion (r = -0.025, P = .76). Regression analysis identified a 0.5-degree reduction in post-TAA dorsiflexion with each 0.1-unit increase in JLHR (Coeff. = -5.13, P = .005). In this patient cohort, we found that an elevated joint line modestly correlated with decreased postoperative dorsiflexion, total ROM, and worse 1-year PROMIS scores. These data suggest that effort likely should be made toward restoring the native joint line at the time of TAA. In addition, future studies investigating the clinical outcomes after TAA may consider including a measure of joint line height, such as the JLHR, because we found it was associated with patient-reported outcomes. Level III, retrospective review of prospectively collected data.

Influence of Joint Line Level on Clinical Outcomes and Range of Motion in Total Ankle Arthroplasty

Category: Ankle Arthritis; Ankle Introduction/Purpose: Restoring the native joint line correlates with better clinical outcomes in total knee arthroplasty. Yet, the effect of joint line elevation on clinical outcomes after total ankle arthroplasty (TAA) remains unclear. A previous study reported that pre- and post-TAA joint line heights, as measured by the joint line height ratio (JLHR), were elevated compared to non- arthritic ankles. However, the clinical impact of this has yet to be determined. Therefore, this study assessed the relationship between the TAA joint line level with post-TAA range of motion (ROM) and PROMIS scores. We hypothesized that an elevated joint line would be associated with restricted post-TAA dorsiflexion and worse postoperative PROMIS scores. Methods: This is a single-center review of 150 patients who underwent primary TAA. Patients with (1)fibular or medial malleolar osteotomy, (2) component subsidence, and (3) incomplete radiographs or outcome scores were excluded. Demographic data, surgical protocol, pre- and postoperative radiographs, and 1-year postoperative PROMIS scores were reviewed. Radiographic measurements included JLHR, pre- and post-TAA tibiotalar dorsiflexion and plantarflexion, and tibial component sagittal alignment. Two graders measured post-TAA JLHRs, and the average of the two graders was used for the analysis. Rater agreement was assessed using intraclass correlation coefficients (two-way random effects model). Relationships between JLHR, post-TAA tibiotalar ROM, and PROMIS scores were investigated using Pearson correlation. Multiple linear regression models were used to investigate the association of JLHR with post-TAA tibiotalar total ROM, dorsiflexion, and plantarflexion, after adjusting for pre- TAA ROM, tibial component sagittal alignment, gastrocnemius release (GR), Tendo-Achilles lengthening (TAL), and polyethylene size. Results: The interobserver reliability of the JLHR was excellent (r=0.98). Mean JLHR decreased from 1.66 pre-TAA to 1.55 post- TAA (P &lt; 0.001), indicating the joint line was significantly lowered postoperatively. Greater elevation of the post-TAA JLHR was associated with significantly decreased post-TAA dorsiflexion (r=-0.26, P&lt; 0.001) and worse 1-year PROMIS physical function (r=- 0.22, P=0.046), pain intensity (r=0.22,P=0.042), and pain interference scores (r=0.29,P=0.007). There was no correlation between JLHR and post-TAA plantarflexion (P=0.76). Regression analysis identified a 5º reduction in post-TAA dorsiflexion with each 1.0 unit increase in JLHR (Coef=-5.13, P=0.005). Post-TAA total ROM (Coef=-3.6,P=0.21) and plantarflexion (Coef=0.91, P=0.67) were not associated with JLHR. Additionally, there was no association between post-TAA total ROM and tibial component sagittal alignment, GR, TAL, or polyethylene size. Conclusion: In this study, the joint line of the ankle was lowered after TAA, and the JLHR was a reliable and clinically applicable method for assessing it. An elevated joint line significantly correlated with restricted post-TAA dorsiflexion, but this may only be clinically relevant for patients with significant (&gt;1.0 unit) changes in the joint line level. In addition, a higher joint line was correlated with worse 1-year PROMIS scores. These results suggest that surgeons should consider the joint line level during TAA preoperative planning to obtain improved clinical outcomes and ankle dorsiflexion.

Maintenance of the joint line and posterior condylar offset are the most notable variables for successful outcomes of revision total knee arthroplasty.

Controversy regarding which variables should be prioritized for better outcomes in revision total knee arthroplasty (RTKA) exists. This study aimed to comprehensively analyze the variables affecting RTKA outcomes. We retrospectively identified 87 RTKAs in 82 patients who were performed between March 2014 and February 2020. Range of motion (ROM), including flexion contracture (FC) and further flexion (FF), was analyzed according to the covariates. The covariates included mode of failure, joint line position, anteroposterior (AP) position, rotational alignment of the femoral component, and patellofemoral alignment. The differences between the final follow-up values of each RTKA variable and those of the native knee were evaluated. The clinical outcomes were evaluated. No significant differences were observed between the joint line positions of the RTKA and native knees. The patellar and AP positions of the femoral component were restored to pre-TKA values. The femoral component had an external rotation of 2.78° compared with the native knee. In multivariable stepwise regression analysis, restoration of the adductor tubercle joint line and posterior condylar offset (PCO) were significant variables affecting ROM. Septic RTKA (33 knees) resulted in poor FF outcomes (p = 0.030) and Western Ontario and McMaster Universities Osteoarthritis Index stiffness (WOMAC S) scores (p < 0.001), compared with aseptic RTKA (54 knees). Restoration of the joint line position and PCO are crucial factors for improved ROM in RTKA. Joint line elevation in RTKA resulted in worse ROM than joint line lowering. In addition, RTKA due to septic failure had inferior ROM and WOMAC S scores compared with RTKA due to aseptic failure. Level III, cohort study.

Differences in joint line level and posterior condylar offset during total knee replacement with use of gap-balancing and measured resection techniques—matched cohort study

BackgroundTotal knee replacement (TKR) is considered one of the most common elective orthopaedic procedures. The main focus of TKR is to offer patient's symptomatic relief from persistent knee pain. To achieve this it is crucial to restore joint biomechanics by performing proper bone cuts. Some surgeons favor the measured resection technique, others prefer gap balancing technique. The researchers of the presented study performed TKR using these two techniques. The aim of this study was to compare the postoperative change in joint line and posterior condylar offset after TKR with use of anatomic knee design implants between gap balancing and measured resection techniques.MethodsTwo hundred twenty-five X-rays of patients who underwent TKR performed by a single surgeon between 2020 and 2021 were analyzed. The first group of patients (101) was operated with the use of gap balancing technique and the second group (124) was operated with the use of measured resection technique. Patients included in the study were > 50 years of age, had confirmed primary knee osteoarthritis, underwent primary TKR with a PS (posterior stabilized) knee implants without patella resurfacing and had at least 15 degree flexion contracture. T-student test and U Mann–Whitney test were used in statistical analysis of results, according to the normality of distribution examined with the Shapiro–Wilk test. Post-hoc analysis was performed using the Dwass-Steel-Crichtlow-Fligner test (DSCF).ResultsThe postoperative analysis showed a significantly elevated joint line level in the gap balancing group (-2.6 ± 4.1 vs -0.7 ± 4.8, p < 0.0005). In the gap balancing group significantly more patients had joint lines elevated > 2 mm comparing to measured resection technique. The difference between pre- and postoperative PCO (posterior condylar offset) and PCOR (posterior condylar offset ratio) results had no significant differences (100.8 ± 11.8 vs 101 ± 12.5, p > 0.05) between the groups.ConclusionsThe results of the study suggest that when it comes to restoring joint line level measured resection technique seems to be superior in comparison to the gap balancing technique. What is more, results indicate measured resection is equal in terms of restoring posterior condylar offset to the gap balancing technique.Trial registrationNCT04164147, date of registration: November 14, 2019.

A Narrative Review of Patellar Resurfacing Versus Non-resurfacing in Total Knee Arthroplasty.

The number of individuals who experience the symptoms of gonarthrosis rises proportionally as life expectancy rises and the population becomes more active. The purpose of total knee arthroplasty (TKA) is to lessen pain and restore knee function, and it has a high success rate. The restoration of patellar tracking in addition to the proper alignment of the femoral and tibial components contributes to the success of the arthroplasty and the patient's happiness. Replacement of the knee is not an easy process. One of the major objectives of total knee replacement is to achieve the proper rotation of the femoral components. A critical step that affects postoperative outcomes in total knee arthroplasty is the correct alignment of the femoral component. The axial plane of the femoral component is to blame for flexion stability, knee joint kinematics, flexion alignment, and patellar tracking. The patella is the largest sesamoid bone in the human body, and its major role is to enhance the quadriceps' moment arm, which allows the knee to expand. The distribution of patellofemoral compressive pressures during knee flexion and the centralization of the quadriceps muscles' multidirectional pull during extension are both critical functions of the patella. After primary knee arthroplasty, there are 8% more cases of anterior knee discomfort than there were before. Whether or not the patella was resurfaced, patients with primary TKA experience anterior knee discomfort. Patella baja is caused by excessive joint line elevation, which causes persistent overload and discomfort. The design of the TKR might have an impact on postoperative patellofemoral problems. After TKR, patellofemoral maltracking and patellar dislocation are often caused by surgical mistakes.

Identification of the joint line in revision total knee arthroplasty using a multiple linear regression model: a cadaveric study.

The results of revision total knee arthroplasty (rTKA) may be compromised by excessive joint line (JL) elevation. It is critical but challenging in reestablishing the JL in rTKA. Previous studies have confirmed that, biomechanically and clinically, JL elevation should not exceed 4mm. Image-based studies described several approaches to locate the JL intraoperatively, however magnification errors could occur. In this cadaveric study, we aim to define an accurate and reliable method to determine the JL. Thirteen male and eleven female cadavers were used, with an average age of death being 48.3years. The transepicondylar width (TEW), the distance from the medial (MEJL) and lateral (LEJL) epicondyle, adductor tubercle (ATJL), fibular head (FHJL) and tibial tubercle (TTJL) to the JL were measured in 48 knees. Intra- and interobserver reliability and validity were tested prior to any additional analysis. Pearson correlation and linear regression analysis were used to examine the correlations between landmark-JL distances (LEJL, MEJL, ATJL, FHJL and TTJL) and the TEW, and to further derive models for intraoperative JL determination. The accuracy of different models, quantified by errors between estimated and measured landmark-JL distances, was compared using the Friedman and post hoc Dunn tests. The intra- and inter-observer measurements for TEW, MEJL, LEJL, ATJL, TTJL and FHJL did not differ significantly (p > 0.05). Between genders, significant differences were found on TEW, MEJL, LEJL, ATJL, FHJL and TTJL (p < 0.05). There was no association between TEW and either FHJL or TTJL (p > 0.05), while ATJL, MEJL, and LEJL were found to be correlated with TEW (p < 0.05). Six models were derived: (1) MEJL = 0.37*TEW (r = 0.384), (2) LEJL = 0.28*TEW (r = 0.380), (3) ATJL = 0.47*TEW (r = 0.608), (4) MEJL = 0.413*TEW-4.197 (R2 = 0.473), (5) LEJL = 0.236*TEW + 3.373 (R2 = 0.326), (6) ATJL = 0.455*TEW + 1.440 (R2 = 0.556). Errors were defined as deviations between estimated and actual landmark-JL distances. The mean absolute value of the errors, created by Model 1-6 was 3.18 ± 2.25, 2.53 ± 2.15, 2.64 ± 2.2, 1.85 ± 1.61, 1.60 ± 1.59 and 1.71 ± 1.5, respectively. The error could be limited to 4mm in 72.9%, 83.3%, 72.9%, 87.5%, 87.5%, and 93.8% of the cases by referencing Model 1-6, respectively. Compared to previous image-based measurements, the current cadaveric study most closely resembles a realistic view of intraoperative settings and could circumvents magnification errors. We recommend using Model 6, the JL can be best estimated by referencing the AT and the ATJL can be calculated as ATJL (mm) = 0.455*TEW (mm) + 1.440 (mm).

Preliminary outcomes following revision total knee arthroplasty using a new fixed-bearing revision knee system in Asians: a mean of 3-year follow-up

PurposeThe purpose of this study was to investigate the early outcomes of the new semi-constrained revision total knee arthroplasty (TKA) system by performing subgroup analysis according to the revision cause.Materials and methodsFrom August 2019 to July 2020, 83 revision TKAs using the fixed-bearing Attune® revision knee system with a minimum follow-up of 2 years were retrospectively reviewed. Clinically, the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, the Western Ontario and McMaster Universities Osteoarthritis Index, and range of motion (ROM) were evaluated. The incidence of systemic and specific postoperative complications was investigated. Each cohort was divided into septic (group A, 34 patients) and aseptic mode (group B, 41 patients), and compared to assess the outcomes.ResultsThe mean age at the time of revision was 73.3 years (range 59.0 to 84.0 years), and the follow-up duration was 36.1 months (range 30.0 to 40.0 months). Clinical outcomes and ROM significantly improved at last follow-up (p < 0.001). Group A showed statistically inferior clinical outcomes in the last follow-up compared to group B. Four knees (5.3%) had a postoperative femoral joint line elevation of more than 5 mm. There were no serious systemic complications. One patient underwent re-revision TKA due to recurrence of infection. No stem tip impingement or cortical erosion was observed in all patients.ConclusionsRevision TKAs using a new semi-constrained revision system showed favorable short-term follow-up outcomes, with improvement in clinical scores and ROM. Moreover, by using stem offsets, no postoperative stem tip impingement or cortical erosion was found.Level of evidenceLevel IV, Retrospective Case Series.

The Effect of Tibiotalar Joint Line Level Alterations on Tibiotalar Range of Motion Following Total Ankle Arthroplasty

Category: Ankle; Ankle Arthritis Introduction/ Purpose: With the increased utilization of total ankle arthroplasty (TAA) for the treatment of end-stage ankle arthritis, the effect of joint line level on patient outcomes remains unclear. It has previously been demonstrated that patients with end-stage ankle arthritis have an elevated joint line level compared with nonarthritic ankles, and the joint line post-TAA remains elevated compared with nonarthritic ankles. The objectives of this study were to (1) Propose a reliable radiographic method to measure the ankle joint line level that can be applied both pre- and postoperatively following TAA and (2) Determine the effect of joint line level alterations in relation to tibiotalar range of motion (ROM) following TAA. Methods: A retrospective review was performed on patients who underwent a TAA at a single institution between January 2018 to April 2021. Inclusion criteria required patients to have a minimum of one-year postoperative follow-up with preoperative weight-bearing anteroposterior (AP) radiographs and postoperative weight-bearing AP and lateral flexion-extension ROM radiographs. Patients with concomitant procedures affecting ROM were excluded. Radiographic joint line and ROM measurements were performed by two observers. The proposed joint line measuring technique computes four joint line measurements for each AP radiograph- high, low, center of the talus, and center of the axis (Figure 1). Paired T-tests, Student T-tests, Chi-Square tests, univariable and multivariable regression models, and Spearman Correlation Coefficients were computed. The ankles were divided into two cohorts for subanalyses- lowered versus elevated joint line. Intra-class correlation coefficients (ICC) were calculated to assess inter-observer reliability. A probability of 0.05 or less was considered significant for all analyses. Results: A total of 33 patients were included with 17(51.5%) valgus-aligned ankles and 16(48.5%) varus ankles. The average postoperative tibiotalar ROM was 6.7°(±7.1°) dorsiflexion to 21.7°(±8.3°) plantarflexion. 22 patients had a lowered joint line compared to 11 patients with an elevated joint line (2.2±1.25mm lowered versus 1.9±1.2mm elevated; p&lt; 0.0001). Of the four joint line measurements, three(high, center, axis) demonstrated a significant positive correlation between lowering the joint line and improved tibiotalar dorsiflexion and total ROM (all p&lt; 0.05). Plantarflexion was not significantly affected by joint line alterations. Compared to patients with an elevated joint, patients with a lowered joint line had improved tibiotalar dorsiflexion (8.8° versus 2.5°; p=0.0015) and total ROM (31.0° versus 22.9°; p=0.0191), respectively. The inter-rater reliability was nearly perfect, ranging from ICC=0.96-0.99. Conclusion: Lowering the tibiotalar joint line level may more closely reestablish the native tibiotalar joint line and results in improved tibiotalar dorsiflexion and total ROM following TAA. This evidence may refute the concern that “overstuffing” the joint decreases postoperative ROM.

The influence of joint line restoration on functional outcome after primary total knee arthroplasty: A prospective study

ObjectiveRestoration of proper joint line position after primary total knee arthroplasty (TKA) is important for improved knee function and kinematics. We reviewed the magnitude of joint line alteration and the resulting effect on post-operative knee outcomes scores at one year follow-up. Materials and methods120 patients who underwent TKA for primary osteoarthritis knee were included. Assessment of joint line position before and after surgery was performed with the help of bony landmarks (excluding osteophytes): Medial Epicondyle Joint Line distance (MEJL), Lateral Epicondyle Joint Line distance (LEJL) and Fibula Head Joint Line distance (FHJL) were calculated. Post-operative knee function was assessed using ‘The Western Ontario and McMaster Universities Arthritis Index’ (WOMAC) and ‘Knee Society Score’ (KSS) at one year follow-up. ResultsJoint line elevation was observed in 104/120 (86.7%) patients and 16/120 (13.3%) patients had no joint line elevation. The mean joint line elevation was 3.00 (±2.13) mm. The patients were sub-classified into two study groups: Group A- Joint line elevation <5 mm and Group B- Joint line elevation ≥ 5 mm. The mean post-op one-year KSS score was significantly higher in patients in Group A compared to Group B (52.82 ± 7.564 vs. 40.73 ± 7.146; p < 0.001). The mean post-op one-year WOMAC score was lower in patients in Group A compared to Group B (65.51 ± 14.762 vs.75.64 ± 8.203) and the difference was statistically significant (p = 0.002). ConclusionElevation of joint line ≥5 mm from the pre-operative value has a negative impact on post-operative functional outcome in primary TKA.

Up to 4 millimeters excessive distal femoral resection in total knee arthroplasty has no significant effect on patellar height and functional score in patient with severe flexion contracture: a retrospective study

Background: Excessive distal femoral resection in patients with severe preoperative flexion contracture has been previously attributed to the joint line elevation after performing total knee arthroplasty (TKA). In this study, the authors investigated the effects of excessive distal femoral cut on the patellar height as well as the outcome of TKA. Methods: This retrospective study included patients with severe flexion contracture (&gt;30°) who underwent TKA. They were divided into two groups according to the size of distal femoral cut: group A (≤9 mm, n=27) and group B (&gt;9 mm, n=22). The functional and radiographic outcomes as well as radiographic indices of patellar height, including adductor ratio, Insall-Salvati index, Blackburne-Peel index, Caton-Deschamps index, and fibular height, were compared between these two study groups. Results: The baseline characteristics of the participants were comparable. The mean femoral cut was 8.3±0.8 in group A and 12.6±0.9 in group B. The mean changes of the adductor ratio, Insall-Salvati index, Caton-Deschamps index, Blackburne-Peel index, and fibular height were not significantly different between the two study groups. As well, the functional and radiographic outcomes of TKA were comparable. No revision surgery was required during the mean follow-up of 51.7±32.4 mo. No genu recurvatum was recorded, and no patient complained of knee instability. Conclusions: Excessive distal femoral cut does not seem to change patellar height in TKA patients, so it could be used safely for patients with a severe preoperative flexion deformity. Level of Evidence: Level IV.

The Effect of Joint Line Elevation on Patient-Reported Outcomes After Contemporary Revision Total Knee Arthroplasty.

Joint line elevation in revision total knee arthroplasty (rTKA) is considered a risk factor for inferior outcomes, engendering a dogmatic protocol of joint line restoration. However, this precedent is based on historical data using rudimentary revision systems and unvalidated outcome measures. This study's purpose was to evaluate the effect of joint line height elevation on validated patient-reported outcome measures (PROMs) using modern revision implants. A total of 327 rTKAs performed at a single institution were reviewed. Surgical technique prioritized flexion-extension gap balancing and accepted joint line elevation if necessary to achieve a balanced flexion space. Radiographic measurements included changes in joint line height (from preoperative and calculated "intended" anatomic/native) and change in posterior condylar offset. Prospectively collected PROMs were evaluated using multivariate regression. The mean joint line elevation from preoperative and "intended" to postoperative joint line was 4.9±5.7 mm and 7.2±6.6 mm, respectively. The mean increase in posterior condylar offset was 1.0±4.6 mm. Patients within ±5 mm of preoperative joint line height were 3.88× more likely to achieve the substantial clinical benefit for Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (P= .004). An increase from intended joint line height >5 mm was not associated with differences in any other PROMs (P ≥ .165). In contemporary rTKA, recreating the joint line within 5 mm of preoperative improves knee-specific health outcomes. These data support approximating native joint line height as a viable technique to optimize flexion gap balance and subsequent patient outcomes in rTKA. Level III retrospective cohort study.

A Mid-Level Constrained Insert Reduces Coupled Axial Rotation but Not Coronal Mid-Flexion Laxity Induced by Joint Line Elevation in Posterior-Stabilized Total Knee Arthroplasty: A Computational Study.

Surgeons may resect additional distal femur during primary posterior-stabilized (PS) total knee arthroplasty (TKA) to correct a flexion contracture. However, the resultant joint line elevation (JLE) increases mid-flexion laxity. We determined whether a mid-level constraint (MLC) insert reduced mid-flexion laxity after JLE. Six computational knee models were developed using computed tomography scans and average soft tissue properties yielding balanced extension gaps but with a 10° flexion contracture. Distal femoral resections of+2 and+4 mm were simulated with PS and MLC inserts. Varus-valgus ±10 Nm moments were applied at 30°, 45°, and 60° of flexion. Coronal laxity (the sum of varus-valgus angulation) and coupled axial rotation (the sum of internal/external rotation) were measured and compared between insert models. At 30° of flexion, coronal laxities with the PS insert at the+2 and+4 mm resections averaged 7.9° ± 0.6° and 11.3° ± 0.6°, respectively, and decreased by 0.8° (P= .06) and 1.0° (P= .07), respectively, with the MLC insert. PS rotational laxities at the+2 and+4 mm resections averaged 11.1° ± 3.9° and 12.5° ± 4.6°, respectively, and decreased by 5.6° (P= .01) and 7.1° (P= .02), respectively, with the MLC insert. Similar patterns were observed at 45° and 60° of flexion. With additional distal femoral resections to alleviate a flexion contracture, utilizing an MLC insert substantially reduced coupled axial rotation but had a minimal impact on coronal laxity compared to a PS insert. Efforts should be taken to avoid JLE in primary total knee arthroplasty as even MLC inserts may not mitigate coronal laxity.

Restricted kinematic alignment achieves similar relative lateral laxity and greater joint line obliquitycompared to gap balancing TKA.

The purpose of this study was to compare ligament balance and laxity profiles achieved throughout flexion in restricted kinematic alignment (rKA) and gap balancing (GB). rKA and GB both aim to improve soft tissue balance and reduce ligament releases in total knee arthroplasty (TKA). One surgeon performed 68 rKA, another performed 73GB TKAs using the same CR implant and robotic system. rKA limited femoral valgus and tibial varus to 6°, with tibial recuts performed to achieve balance. GB limited tibial varus and femoral valgus to 2°, with femoral resections adjusted to achieve mediolateral balance throughout flexion using predictive-gap planning software. Final joint laxity was measured using a robotic ligament tensioner. Statistical analyses were performed to compare differences in mediolateral balance and joint laxity throughout flexion. Further analyses compared alignment, joint line elevation and orientation (JLO), and frequency of ligament releases and bone recuts. Both techniques reported greater lateral laxity throughout flexion, with GB reporting improved mediolateral balance from 10° to 45° flexion. GB resected 1.7mm more distal femur (p ≤ 0.001) and had greater overall laxity than rKA throughout flexion (p ≤ 0.01). rKA increased JLO by 2.5° and 3° on the femur and tibia (p ≤ 0.001). Pre-operative and post-operative coronal alignment were similar across both techniques. rKA had a higher tibial recut rate: 26.5% vs 1.4%, p < 0.001. rKA and GB both report lateral laxity but with different JLO and elevation. Use of a predictive-gap GB workflow resulted in greater mediolateral gap symmetry with fewer recuts. III, retrospective cohort study.

The effect of restored medial knee anatomy in total knee arthroplasty with the flexion first balancer technique on mid-flexion laxity and functional outcome

BackgroundThe Flexion First Balancer (FFB) technique for total knee arthroplasty (TKA) was developed to maintain the isometry of the medial collateral ligament (MCL) by restoring the medial anatomy of the knee. Inability to correct MCL isometry could hypothetically result in an increased mid-flexion laxity. The aim of the current study was to evaluate if the FFB technique results in improved functional outcome and less mid-flexion laxity compared to Measured Resection (MR).MethodsA cross-sectional study was performed comparing 27 FFB patients with 28 MR patients. Groups were matched for age, gender, BMI and ASA classification. All patient received the cruciate retained type, Vanguard Complete Knee System (Biomet Orthopedics, Warsaw, IN, USA). Stress X-rays of the knee with 30 degrees of flexion were made to assess varus-valgus laxity. Furthermore, three tests were conducted to asses functional outcome: a 6 min walk test, a stair climb test and quadriceps peak force measurements. Mean follow-up was respectively 2.6 (SD 0.4) and 3.9 years (SD 0.2).ResultsThe MR group showed a postoperative elevation in joint line in contrast to the FFB group, the mean difference between the two groups was 3 mm (p < 0.001). No differences in total laxity between the two groups was found. The FFB group showed a higher quadriceps peak force (1.67 (SD 0.55) N/BMI) in comparison with the MR group (1.38 (SD 0.48) N/BMI) (p < 0.05). All other outcome parameters were comparable between the two groups (p: n.s.). Correlation analysis showed a moderate negative correlation between joint line elevation and quadriceps peak force (r = − 0.29, p < 0.05).ConclusionThe FFB technique did not lead to less coronal laxity in the mid-flexion range compared to MR. Although peak quadriceps force was significantly higher for the FFB group no clinically relevant benefits could be identified for the patients with regards to functional outcome. Therefore, minor deviations in joint line seems to have no effect on functional outcome after TKA.Trial registrationISRCTN, ISRCTN85351296. Registered 23 april 2021 - Retrospectively registered, https://www.isrctn.com/ISRCTN85351296

Factors Affecting Squatting Ability in Total Knee Arthroplasty Using High Flexion Prosthesis.

PurposeTotal knee arthroplasty (TKA) is widely used as a treatment for knee osteoarthritis. Few studies have analysed the factors affecting the squatting ability of patients after TKA. The purpose of this study was to comprehensively analyse the factors affecting squatting ability after TKA and to determine which ones are important.Patients and MethodsThree hundred primary TKA cases with a minimum 3-year follow-up were retrospectively analysed. All patients received a conventional posterior-stabilized TKA implant and underwent a standard perioperative care pathway. The patients were divided into two groups according to the squatting position and knee flexion angle while weight-bearing (Group I – inability to squat group, Group II – ability to squat group). Demographic, operative, and clinical data were collected. Radiographic assessment included joint line elevation, patellar position, posterior condylar offset (PCO), etc. Statistical analysis of the effect of all the above factors on squatting ability was performed.ResultsThe preoperative range of motion and joint line of Group I were 82.9±12.6 and 3.24±1.07, respectively, and those of Group II were 107±9.6 and 1.83±0.89 respectively. The univariate analysis showed that age, prosthesis size, preoperative ROM and joint line position were correlated with squatting ability. But in the final multivariate analysis, joint line position and preoperative ROM were independent influencing factors that affected squatting ability after TKA (p value < 0.01).ConclusionPreoperative ROM and joint line position were independent influencing factors affecting squatting ability after TKA. Patients should be counseled accordingly and be made to understand these factors. To ensure that patients can squat postoperatively, we should improve surgical techniques to control joint line elevation.

Radiographic Findings in Flexion Instability after Total Knee Arthroplasty.

Flexion instability (FI) is one of the leading causes of knee pain and revision surgery. Generally, the biomechanical etiology is considered to be a larger flexion than extension gap. This may be due to mismatch of components sizes to the bone or malalignment. Other factors such as muscle weakness may also play a role, and the diagnosis of FI after total knee arthroplasty (TKA) relies on a combination of patient's complaints during stair descent or walking and physical examination findings. Our study examines the role of implant positioning and sizes in the diagnosis of FI. A retrospective review of 20 subjects without perceived FI and 13 patients diagnosed with FI after TKA was conducted. Knee injury and osteoarthritis outcome scores (KOOS) were documented, and postoperative radiographs were examined. Measurements including included tibial slope, condylar offset, femoral joint line elevation along with surrogate soft-tissue measures for girth and were compared between groups. The FI group was found to have a significantly lower KOOS score compared with the non-FI group (55.6 vs. 73.5; p = 0.009) as well as smaller soft-tissue measurements over the pretubercle region (6.0 mm vs. 10.6 mm; p = 0.007). Tibial slope, condylar offset ratios, and femoral joint line elevation were not significantly different between the FI and non-FI groups. We noted a significant difference in tibial slope in posterior-stabilized implants in subjects with and without FI (6.4° vs. 1.5°; p = 0.003). Radiographic measurements consistent with malalignment were not indicative of FI. X-ray measurements alone are not sufficient to conclude FI as patient symptoms, and clinical examinations remain the key indicators for diagnosis. Radiographic findings may aid in surgeon determination of an underlying cause for an already identified FI situation and help in planning revision surgery.

Changes in the patellar height following open wedge high tibial osteotomy

Genu varum of the knee is a predisposing factor for osteoarthritis of the medial femoro-tibial compartment. High tibial osteotomy is the surgery of choice for such patients. Patello-femoral abnormalities have a negative effect on the prognosis of high tibial osteotomy. The aim of this study is to assess the changes in patellar height after medial open wedge high tibial osteotomy.Our study was performed in kafr el sheikh university hospital, orthopedic department during the period 2018-2019 on 30 patients.All patients were subjected to thorough clinical and radiological examination and follow up of all patients with Modified Hospital for Special Surgery knee scoring scale (modified HSS), was utilized and compared with its pre-operative valuesThere was significant decrease of patellar height from preoperatively postoperatively; this difference was statistically highly significant.The conclusion was that the High tibial osteotomy using the medial opening wedge technique causes reduction in patellar height due to relative joint line elevation and obliquity and it may be almost inevitable after this type of osteotomy.

Additional distal femoral resection increases mid-flexion coronal laxity in posterior-stabilized total knee arthroplasty with flexion contracture : a computational study.

Surgeons commonly resect additional distal femur during primary total knee arthroplasty (TKA) to correct a flexion contracture, which leads to femoral joint line elevation. There is a paucity of data describing the effect of joint line elevation on mid-flexion stability and knee kinematics. Thus, the goal of this study was to quantify the effect of joint line elevation on mid-flexion laxity. Six computational knee models with cadaver-specific capsular and collateral ligament properties were implanted with a posterior-stabilized (PS) TKA. A 10° flexion contracture was created in each model to simulate a capsular contracture. Distal femoral resections of + 2 mm and + 4 mm were then simulated for each knee. The knee models were then extended under a standard moment. Subsequently, varus and valgus moments of 10 Nm were applied as the knee was flexed from 0° to 90° at baseline and repeated after each of the two distal resections. Coronal laxity (the sum of varus and valgus angulation with respective maximum moments) was measured throughout flexion. With + 2 mm resection at 30° and 45° of flexion, mean coronal laxity increased by a mean of 3.1° (SD 0.18°) (p < 0.001) and 2.7° (SD 0.30°) (p < 0.001), respectively. With + 4 mm resection at 30° and 45° of flexion, mean coronal laxity increased by 6.5° (SD 0.56°) (p < 0.001) and 5.5° (SD 0.72°) (p < 0.001), respectively. Maximum increased coronal laxity for a + 4 mm resection occurred at a mean 15.7° (11° to 33°) of flexion with a mean increase of 7.8° (SD 0.2°) from baseline. With joint line elevation in primary PS TKA, coronal laxity peaks early (about 16°) with a maximum laxity of 8°. Surgeons should restore the joint line if possible; however, if joint line elevation is necessary, we recommend assessment of coronal laxity at 15° to 30° of knee flexion to assess for mid-flexion instability. Further in vivo studies are warranted to understand if this mid-flexion coronal laxity has negative clinical implications. Cite this article: Bone Joint J2021;103-B(6 Supple A):87-93.

The influence of joint line position on functional outcome in primary total knee arthroplasty

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; To find out the cut off for position of joint line which will provide a good functional outcome.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods:&lt;/strong&gt; 58 patients underwent total knee arthroplasty using standard medial parapatellar approach were included in this study. Pre-operative and post-operative radiological joint line were assessed. Pre-operative and post-operative functional assessment were done using oxford knee score and International knee society score. functional outcome was assessed at 1, 3 and 6 months. Influence of post-operative joint line change on functional outcome was assessed on follow up visit in 6&lt;sup&gt;th &lt;/sup&gt;month.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results:&lt;/strong&gt; Of 58 patients studied, mean age ± SD was 69.0±7.5 years. Joint line elevation of 36, 16, 8 and 2 patients were between 0-2, 2-4 4-8 and&amp;gt;8 mm respectively with mean ± SD of joint line elevation of 2.24±2.07 mm in the group. Mean OKS-knee score at 6 months follow-up of study group was 36.60 with mean IKSS-knee score of 38.17 at 6 months follow up of group&amp;lt;4 mm which was significant (p&amp;lt;0.05) when compared to mean IKSS-knee score at 6 months follow up of group&amp;gt;4 mm (28.40).&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; It was concluded that joint line restoration is necessary for getting a good functional outcome after primary total knee arthroplasty. The functional outcome of patients with joint line elevation between 4-8mm showed inferior outcomes in comparison to the patients with joint line elevation within 4 mm.&lt;/p&gt;

Extensor mechanism failure in total knee arthroplasty

Extensor mechanism failure in total knee arthroplasty (TKA) can present as quadriceps tendon rupture, patella fracture or patella tendon rupture.Component malrotation, excessive joint line elevation and previous lateral release are some of the risk factors contributing to extensor mechanism failure in TKA.Partial quadriceps tendon rupture and undisplaced patella fracture with intact extensor mechanism function can be treated conservatively.Extensor mechanism failure in TKA with disruption of the extensor mechanism function should be treated operatively as it is associated with poor function and extensor lag.It is recommended that acute repair of patella or quadriceps tendon rupture are augmented due to the high risk of re-rupture.Chronic ruptures of the extensor mechanism must be reconstructed as repair has a high failure rate. Reconstruction can be performed using autograft, allograft or synthetic graft.Cite this article: EFORT Open Rev 2021;6:181-188. DOI: 10.1302/2058-5241.6.200119