Instability In Total Knee Arthroplasty Research Articles

Functionally aligned total knee arthroplasty: A lateral flexion laxity up to 6 mm is safe!

Loose flexion gaps are associated with poor functional outcomes and instability in total knee arthroplasty (TKA). The effect of a trapezoidal flexion gap in a functionally aligned TKA remains unknown. The aim of this study was to investigate the effect of a larger lateral flexion gap in a robotic-assisted (RA), functionally aligned (FA) andcruciate-retaining (CR) TKA on clinical outcomes. Data from 527 TKA in 478 patients from 2018 to 2020 werecollected. All patients underwent an RA (MAKO, Stryker), FA andCR TKA. Gap measurements were collected intraoperatively. Patient-reported outcome measures (PROMs), pain Visual analogue score (VAS)and range of motion were collected postoperatively. Patients were also asked about the ease of stair ascent and descent and kneeling on a 5-point scale. The minimum follow-up was 2 years. Patients were stratified into three groups based on lateral flexion laxity. At 2 years postoperatively, the group with a looser gap (3-6 mm) had higher mean PROMs when compared with the group with a gap of 2-3 mm. There were no differences detected in any other outcomes at 2 years. A total of 70.9% of patients in the group with a 3-6 mm gap reported being able to walk down a flight of stairs 'easily', compared with 56.7% in the 2-3 mm group and 54% in the <2 mm group (p = 0.04). The study shows that a loose lateral flexion gap in functionally aligned CR TKA does not adversely affect outcomes in the short term. Level III, retrospective cohort study.

Treatment of Postoperative Instability Following Total Knee Arthroplasty in Patients With Parkinson’s Disease

Acute postoperative posterior total knee arthroplasty (TKA) dislocation is rare in primary surgery but has been associated with Parkinson’s disease (PD). We present a 77-year-old woman with knee arthritis and PD who sustained an acute, recurrent TKA posterior dislocation, recalcitrant to polyethylene upsizing. Transient stability was obtained for a period of 1 year after postoperative hamstring injection with botulinum toxin A and short-term immobilization. Spontaneous instability recurred after 1 year, and stability was obtained with revision to a more constrained construct and has been monitored over a period of 2 years. This is the first report demonstrating the use of botulinum toxin A for acute posterior TKA instability associated with PD. We endorse the necessity of increased constraint to maintain long-term stability in patients with Parkinson’s disease.

Isolated Liner Exchange Versus All-Component Revision for Instability After Total Knee Arthroplasty

BackgroundInstability is a common cause for revision total knee arthroplasty (TKA). The risks and benefits of polyethylene liner exchange (LE) as compared to full metal component revision continue to be debated. The purpose of this study was to investigate the success rate and complication profiles of revision TKA for instability based on surgical procedure. MethodsThis was a retrospective study of patients undergoing revision TKA for instability from 2015 to 2019. Patients with prior revisions were excluded. 42 patients undergoing isolated polyethylene LE without an increase in constraint were compared with 48 patients undergoing full component revision revision (FCR) of both tibial and femoral components. The primary outcome was differences in rerevision for instability. Noninstability reoperations, 90-day readmissions, and lengths-of-stay were also compared. ResultsLEs had a 10.1% higher rerevision for instability rate that approached statistical significance (LE 14.3% versus FCR 4.2%, P = .092). Additionally, FCR had a 4.2% rate of aseptic loosening and a 4.2% rate of periprosthetic-joint-infection, whereas LE had none (P = .181). FCR also had a longer length-of-stay (FCR 3.0 ± 1.3 versus LE: 1.8 ± 0.9 days, P < .001). No differences were found in 90-day readmissions (LE 7.1% versus FCR 4.2%, P = .661). ConclusionAll component revision may have a higher success rate than isolated LE in addressing instability but is associated with higher rates of surgical complications. With appropriate patient selection and risk-benefit discussion, isolated LE may be a reasonable surgical option for TKA instability with a lower complication profile and length-of-stay.

Balance and constraint in revision TKR: A classification for instability management

Instability is an increasingly common cause and symptom of failure of Total Knee Arthroplasty (TKA). Patients seek ‘Functional Stability’, which is the sum of both a balanced joint and, if necessary, mechanical constraint. The objective of this paper is to classify the different types of TKA instability and their causes. Based on this classification, the authors give methodical recommendations for instability management. Instability classificationInstability in revision TKA can be classified into 3 types based on the management of bone loss and ligamentous deficiency which directs the level of constraint required to achieve functional stability. Type 1Bone deficiency: Revision with restoration of joint line and rebuilding the bony anatomy results in a balanced joint. No increased constraint is needed. Type 2Ligament and soft tissue deficiency: Requires increased constraint to overcome instability Type 3Composite (Total) deficiency: (combined Type 1 and 2).The multiple causes of instability are outlined for each Instability type along with an algorithm for restoring the joint line and adding titrated constraint to restore functional stability.

Isolated Liner Revision for Total Knee Arthroplasty Instability: A Road That Should Remain Less Taken.

Isolated polyethylene liner exchange (IPLE) is infrequently selected as a treatment approach for patients with primary total knee arthroplasty (TKA) prosthetic joint instability. Potential advantages of less immediate surgical morbidity, faster recovery, and lower procedural cost need to be measured against reoperation and re-revision risk. Few published studies have directly compared IPLE with combined tibial and femoral component revision to treat patients with primary TKA instability. After obtaining institutional review board (IRB) approval, we performed a retrospective comparison of 20 patients treated with IPLE and 126 patients treated with tibial and femoral component revisions at a single institution between 2011 and 2018. Patient demographic characteristics, medical comorbidities, time to initial revision TKA, and reoperation (90 days, <2 years, and >2 years) were assessed using paired Student's t-test or Fisher's exact test with a p-value <0.01 used to determine significance. Patients undergoing IPLE were more likely to undergo reoperation (60.0 vs. 17.5%, p = 0.001), component revision surgery (45.0 vs. 8.7%, p = 0.002), and component revision within 2 years (30.0 vs. 1.6%, p < 0.0001). Differences in 90-day reoperation (p = 0.14) and revision >2 years (p = 0.19) were not significant. Reoperation for instability (30.0 vs. 4.0%, p < 0.001) and infection (20.0 vs. 1.6%, p < 0.01) were both higher in the IPLE group. IPLE does not provide consistent benefits for patients undergoing TKA revision for instability. Considerations for lower immediate postoperative morbidity and cost need to be carefully measured against long-term consequences of reoperation, delayed component revision, and increased long-term costs of multiple surgical procedures. This is a level III, case-control study.

The evaluation of the distance between the popliteus tendon and the lateral collateral ligament footprint and the implant in Total knee Arthroplasty using a 3-dimensional template

BackgroundThe popliteus tendon (PT) or lateral collateral ligament (LCL) stabilizes the postero-lateral aspects of the knees. When surgeons perform total knee arthroplasty (TKA), PT and LCL iatrogenic injuries are a risk because the femoral attachments are relatively close to the femoral bone resection area. The purpose of this study was to evaluate the distance between the PT or LCL footprint and the TKA implant using a 3D template system and to evaluate any significant differences according to the implant model.MethodsEighteen non-paired formalin fixed cadaveric lower limbs were used (average age: 80.3). Whole length lower limbs were resected from the pelvis. All the surrounding soft tissue except the PT, knee ligaments and meniscus were removed from the limb. Careful dissection of the PT and LCL was performed, and the femoral footprints were detected. Each footprint periphery was marked with a 1.5 mm K-wire. Computed tomography (CT) scanning of the whole lower limb was then performed. The CT data was analyzed with a 3D template system. This simulation models for TKA were the Journey II BCS and the Persona PS. The area of each footprint, and the length between the most distal and posterior point of the lateral femoral condyle and the edge of each footprint were measured. Matching the implant model to the CT image of the femur, the shortest length between each footprint and the bone resection area were calculated.ResultsPT and LCL footprint were detected in all knees. The area of the PT and LCL footprints was 38.7 ± 17.7 mm2 and 58.0 ± 24.6 mm2, respectively. The length between the most distal and posterior point of the lateral femoral condyle and the edge of the PT footprint was 10.3 ± 2.4 mm and 14.2 ± 2.8 mm, respectively. The length between most distal and most posterior point of the lateral femoral condyle and the edge of the LCL footprint was 16.3 ± 2.3 mm and 15.5 ± 3.3 mm, respectively. Under TKA simulation, the shortest length between the PT footprint and the femoral bone resection area for the Journey II BCS and the Persona PS was 4.3 ± 2.5 mm and 3.2 ± 2.9 mm, respectively. The shortest length between the LCL footprint and the femoral bone resection area for the Journey II BCS and the Persona PS was 7.2 ± 2.3 mm and 5.6 ± 2.1 mm, respectively. The PT attachment was damaged by the bone resection of the Journey II BCS and the Persona PS TKA in 3 and 9 knees, respectively.ConclusionThe PT and LCL femoral attachments existed close to the femoral bone resection area of the TKA. To prevent postero-lateral instability in TKA, careful attention is needed to avoid damage to the PT and LCL during surgical procedures.

Midflexion instability in total knee arthroplasty: a systematic review.

The aim of this systematic review was to evaluate the evidence on the existence of midflexion instability in primary total knee arthroplasty and which factors might contribute to this condition. A comprehensive search of PubMed, Medline, Cochrane, CINAHL, and Embase databases was conducted since the inception of the database to July 2019. All relevant articles were retrieved, and their bibliographies were hand searched for further references on midflexion instability in primary total knee arthroplasty. The search strategy yielded 28 articles. After duplicate removal titles, abstracts and full text were reviewed. Fifteen studies were assessed for eligibility, 8 studies were excluded because they did not fully comply with the inclusion criteria. Seven articles were finally included in this systematic review. Anteroposterior translation, total knee arthroplasty design such as posterior-stabilized or posterior-cruciate-retaining total knee arthroplasty, joint line position with posterior condylar offset and joint gaps were considered to significantly influence midflexion stability. Based on this systematic review anteroposterior translation of ≥ 7mm was an independent risk factor for midflexion instability at 30° knee flexion. Joint line position can be altered by up to 5mm without measurable changes in joint stability and both an increase and a decrease in posterior condylar offset led to 30° midflexion instability. Midflexion instability in primary total knee arthroplasty remains to be not entirely understood. Due to the low quality of available evidence, it is difficult to make any definitive conclusions. The factors which can lead to this condition were analyzed in this review, furthermore, we did not find exhaustive evidence on midflexion instability existence as an isolated entity. Nonetheless, this review will form a baseline for future research and creates awareness for the routine assessment of midflexion instability in primary total knee arthroplasty. IV.

Bone resection for mechanically aligned total knee arthroplasty creates frequent gap modifications and imbalances.

The objective of this study was to calculate bone resection thicknesses and resulting gap sizes, simulating a measured resection mechanical alignment (MA) technique for total knee arthroplasty (TKA). MA bone resections were simulated on 1000 consecutive lower limb CT scans from patients undergoing TKA. Femoral rotation was aligned with either the surgical trans-epicondylar axis (TEA) or with 3° of external rotation to the posterior condyles (PC). Imbalances in the extension space, flexion space, medial compartment and lateral compartment were calculated. Extension space imbalances (≥ 3mm) occurred in 25% of varus and 54% of valgus knees and severe imbalances (≥ 5mm) were present in up to 8% of varus and 19% of valgus knees. Higher flexion space imbalance rates were created with TEA versus PC (p < 0.001). Using TEA, only 49% of varus and 18% of valgus knees had < 3mm of imbalance throughout the extension and flexion spaces, and medial and lateral compartments. A systematic use of the simulated measured resection MA technique for TKA leads to many cases with imbalance. Some imbalances may not be correctable surgically and may result in TKA instability. Modified versions of the MA technique or other alignment methods that better reproduce knee anatomies should be explored. 2.

Revision knee arthroplasty with rotating hinge systems in patients with gross ligament instability.

The clinical and radiographic outcomes after revision total knee arthroplasty (TKA) for instability with two rotating hinge knee prostheses were compared. Fifty-one patients revised for TKA instability were prospectively randomized to either the Link Endo-Model (N = 26) or the EnduRo (N = 25). Clinical and radiographic outcome scores were compared pre-operatively and at 12months' follow-up. Failure mechanisms were recorded. Age, BMI, operation, and tourniquet-time did not differ significantly between groups. Radiographic evaluation demonstrated correct implant alignment. The Endo-Model was implanted with a higher slope (p = 0.0001) and the mechanical lower extremity axis was straighter (p = 0.0323). Except for the patient function Knee Society Score and the Physical Health Component Summary Score in the EnduRo group, all clinical scores (range of motion/knee function Knee Society Score/Oxford Knee Score/Visual Analog Scale/Mental Health Component Summary Score) improved significantly for both prosthesis designs during the follow-up period. The Visual Analog Scale and Mental Health Component Summary score were significantly better (p = 0.045 and p = 0.0148) in the Endo-Model group at the 12months' follow-up. In the EnduRo group 2 patients (8%) and in the Endo-Model group 1 patient(3.8%) had to be revisedfor infection. Both prosthetic designs provide significant improvement in pain and function scores after TKA revision for gross instability. We found slight advantages in favor of the Endo-Model; however, no design yielded superior results throughout the study.

Increased risk of early and medium-term revision after post-fracture total knee arthroplasty

Background and purpose — Total knee arthroplasty (TKA) due to posttraumatic fracture osteoarthritis (PTFA) may be associated with inferior prosthesis survival. This study is the first registry-based study solely addressing this issue. Both indications and predictors for revision were identified.Patients and methods — 52,518 primary TKAs performed between 1997 and 2013 were retrieved from the Danish Knee Arthroplasty Register (DKR). 1,421 TKAs were inserted due to PTFA and 51,097 due to primary osteoarthritis (OA). Short-term (< 1 year), medium-term (1–5 years), and long-term (> 5 years) implant survival were analyzed using Kaplan-Meier analysis and Cox regression after age stratification (< 50, 50–70, and >70 years). In addition, indications for revision and characteristics of TKA patients with subsequent revision were determined.Results — During the first 5 years, TKAs inserted due to PTFA had a higher risk of revision than OA (with adjusted hazard ratio ranging from 1.5 to 2.4 between age categories). After 5 years, no significant differences in the risk of revision were seen between the groups. Infection and aseptic loosening were the most common causes of revision in both groups, but TKA instability was a more frequent indication for revision in the PTFA group. In both groups, the revision rates were higher with younger age and extended duration of primary surgery.Interpretation — We found an increased risk of early and medium-term revision of TKAs inserted due to previous fractures in the distal femur and/or proximal tibia. Predictors of revision such as age <50 years and extended duration of primary surgery were identified, and revision due to instability occurred more frequently in TKAs performed due to previous fractures.

The Evolution of Implant Design Decreases the Incidence of Lateral Release in Primary Total Knee Arthroplasty

BackgroundAppropriate balancing of the patellofemoral joint (PFJ) using a lateral release can help to prevent patellar instability in total knee arthroplasty (TKA). Contemporary total knee implant designs are characterized by enhanced trochlear geometry more similar to native knee anatomy to minimize instability and reduce utilization of a lateral release. MethodsWe retrospectively reviewed consecutive TKA cases from a single senior surgeon's practice with 3 successive total knee designs: the Press-Fit Condylar (PFC), the Sigma, and the ATTUNE (DePuy, Warsaw, IN). We evaluated the use of lateral release with each implant type to determine if design changes have improved patellar stability, reducing the need for lateral release. We used multivariate analysis to determine the association between implant type and lateral release, adjusting for age, sex, preoperative alignment, and bearing type. ResultsWe evaluated 1991 records of primary TKAs performed from 1980-2015. As compared with the ATTUNE, the adjusted odds of lateral release were greater for patients receiving PFC implants (Odds ratio [OR] 6.35, 95% confidence interval [CI] 3.85,10.49) and Sigma implants (OR 2.02, 95% CI 1.26, 3.23). In addition, fixed bearing implants were associated with greater adjusted odds of lateral release (OR 1.80, 95% CI 1.24, 2.62). ConclusionWe found that older knee implants were associated with higher use of lateral release, with successive designs the need for lateral release to balance the PFJ decreased. Continued design improvements to match the native knee anatomy may further improve the stability of the PFJ in future designs.

Instability in total knee arthroplasty : assessment and solutions.

Instability is a common indication for early revision after both primary and revision total knee arthroplasty (TKA), accounting for up to 20% in the literature. The number of TKAs performed annually continues to climb exponentially, thus having an effective algorithm for treatment is essential. This relies on a thorough pre- and intra-operative assessment of the patient. The underlying cause of the instability must be identified initially and subsequently, the surgeon must be able to balance the flexion and extension gaps and be comfortable using a variety of constrained implants. This review describes the assessment of the unstable TKA, and the authors' preferred form of treatment for these difficult cases where the source of instability is often multifactorial.

The reversed gap technique produces anatomical alignment with less midflexion instability in total knee arthroplasty: a prospective randomized trial.

No surgical technique is capable of controlling the stability of the joint in midflexion. The purpose of the present study was to present and evaluate a surgical technique that aims to reduce the need for soft-tissue release and optimize stability in midflexion. Sixty knee joints were included in this prospective randomized study. Surgery was performed either according to a classical gap (GT) technique or using the reversed gap (RG) technique. In the RG, the femoral component was positioned parallel to the surgical transepicondylar axis using a preoperative MRI and a navigation system. The frontal alignment of the tibia was then selected to produce a symmetric flexion gap. Then, the frontal alignment of the femoral component was adjusted to produce a symmetric extension gap. Soft-tissue release was defined to be extensive if more than two steps or stabilizing structures were involved. Joint stability was measured at different flexion angles (-5° to 120°) using a gap tensioning device and the trial femoral implant. In the GT group, 16 knee joints (53%) showed an instability of more than 2mm at 5°, 30° or 60°, compared with 8 knee joints (27%) in the RG group (p=0.035). The RG did not lead to a reduction in the number of soft-tissue releases, but they were less extensive. RG reduced midflexion instability and the number of extensive soft-tissue releases. It may simplify the operation by reducing the extent of soft-tissue releases and avoid instability-related problems of knee arthroplasty. Nevertheless, it should only be performed under controlled conditions until long-term clinical data are available. I.

Revision of the Unstable Total Knee Arthroplasty: Outcome Predictors

Revision arthroplasty is often required for confirmed cases of symptomatic tibiofemoral instability after total knee arthroplasty (TKA). We evaluated the results of revision for TKA instability in a consecutive series of 67 patients (68 knees) between 2000 and 2006. Outcome measures were surgeon-based assessment of knee stability, Knee Society Score, and Short Form Health Survey 36. At an average of 39 months of follow-up, the mean Knee Society Score and Short Form Health Survey 36 physical and mental scores were 76, 53, and 67 points, respectively. Knee instability persisted in 14 patients (22%). Data at the 95% confidence level revealed that revising both the femoral and tibial components, the use of femoral augments, and smaller joint line elevation as measured on radiographs correlated significantly with achieving a stable knee. In revision surgery for TKA instability, revision of both components and the use of femoral augments seem to offer the most predictable outcome.

Robotic testing of proximal tibio‐fibular joint kinematics for measuring instability following total knee arthroplasty

Pain secondary to instability in total knee arthroplasty (TKA) has been shown to be major cause of early failure. In this study, we focused on the effect of instability in TKA on the proximal tibio-fibular joint (PTFJ). We used a robotics model to compare the biomechanics of the PTFJ in the native knee, an appropriately balanced TKA, and an unbalanced TKA. The tibia (n = 5) was mounted to a six-degree-of-freedom force/torque sensor and the femur was moved by a robotic manipulator. Motion at the PTFJ was recorded with a high-resolution digital camera system. After establishing a neutral position, loading conditions were applied at varying flexion angles (0°, 30°, and 60°). These included: internal/external rotation (0 Nm, ±5 Nm), varus/valgus (0 Nm, ±10 Nm), compression (100 N, 700 N), and posterior drawer (0 N, 100 N). With respect to anterior displacement, external rotation had the largest effect (coefficient = 0.650; p < 0.0001). Polyethylene size as well as the interaction between polyethylene size and flexion consistently showed substantial anterior motion. Flexion and mid-flexion instability in TKA have been difficult to quantify. While tibio-femoral kinematics is the main aspect of TKA performance, the effects on adjacent tissues should not be overlooked. Our data show that PTFJ kinematics are affected by the balancing of the TKA.

How Precise is the Determination of Rotational Alignment of the Femoral Prosthesis in Total Knee Arthroplasty: An In Vivo Study

Correct rotation of the femoral component is critical in avoiding patellar instability in total knee arthroplasty. This study attempted to compare the precision of 4 commonly used methods (transepicondylar axis [TEA], 3° external rotation [ER] from posterior condylar line [PCL], perpendicular cut to Leo Whiteside line [WSL], and balanced flexion gap [GAP]) in determining the rotational alignment of the femoral prosthesis in an in vivo setting. The ranges of error were as follows: (1) TEA, 28° (17° internal rotation [IR] to 11° ER); (2) PCL, 27° (13° IR to 14° ER); (3) WSL, 32° (17° IR to 15° ER); (4) GAP, 26° (14° IR to 12° ER). If an error of more than 5° from neutral alignment is defined as an outlier, 56% in TEA, 72% in PCL, 60% in WSL, and 20% in GAP methods would fall in the outlier zone.

Instability in total knee arthroplasty: Loose as a goose

As total knee arthroplasties last longer and are used in younger patients, as well as for a variety of other reasons, greater interest in postoperative tibiofemoral instability has developed. Initial evaluation emphasizing correlation of symptoms and findings together with elucidation of the specifics of the instability are mandatory. Gap inequality, gap asymmetry, and the causes of each are noted. Soft tissue repair or reconstruction alone has not been very successful for such instabilities. Some aspect of revision with component change is generally necessary, and some correction of alignment, gap features, and other issues, with advancement to a higher order of constraint, will generally be necessary. © 2003 Elsevier Inc. All rights reserved.

Preoperative planning to prevent instability in total knee arthroplasty

Several factors can lead to persistent instability after total knee arthroplasty, including bone and soft tissue loss, preexisting ligamentous laxity, and poor operative technique. Achieving stability should not be equated with making the knee extremely tight, without any natural laxity.

Patellofemoral instability in total knee arthroplasty

Patellofemoral instability following total knee arthroplasty remains one of the major complications requiring operative intervention. In spite of recent advances in technique and instrumentation, the rate of this complication remains disturbingly high. A comprehensive analysis of cause reveals malalignment of any of the components to be potentially responsible, particularly valgus or internal rotation malalignment of either femoral or tibial component, as well as lateral displacement of the patellar component. Underresection of the patella or oversizing the femoral component may also contribute to excessive lateral retinacular tightness. When confronted with patellofemoral instability, the surgeon must first look for and correct the cause. Component malalignment requires component revision. Extensor mechanism imbalance requires either proximal or distal realignment. Lateral release alone invites recurrence of the problem.