Abstract:Purpose: Kinematic alignment (KA) for primary total knee arthroplasty (TKA) has been shown to provide equivalent or better results to mechanical alignment (MA). The use of KA in revision TKA to restore the individual knee anatomy, kinematics, and soft-tissue balance, has not been documented yet. The purpose of this study is to describe the technique for performing TKA revision using the restricted KA (rKA) protocol and to report (1) rerevision rate and adverse events, (2) patient-reported outcome measures (PRO… Show more
“…In the present study, we investigated whether use of the pre-arthritic alignment angle would lead to favorable outcomes following UKA. Because of the general lack of agreement in the literature regarding the optimal postoperative alignment strategy in UKA, we retrospectively assessed patient data to find the pre-arthritic/kinematic alignment angle, as measured on 3-foot (1-m)-long standing radiographs with use of a simple arithmetic method 26,27 . We then assessed whether knees that had postoperative alignment within 3° of their pre-arthritic alignment showed superior results compared with knees that had postoperative alignment outside this range.…”
Background: The optimal alignment strategy in unicompartmental knee arthroplasty (UKA) is debated. Recent studies have suggested that kinematic alignment may lead to improved biomechanics and outcomes. The aim of the present study was to determine if pre-arthritic/kinematic alignment of knees would result in sustained long-term restoration of function, without conversion to total knee arthroplasty (TKA), following non-robotically assisted, fixed-bearing medial UKA.Methods: A total of 236 UKAs were performed from 2000 to 2015. Of these, a total of 150 medial UKAs met the inclusion criteria and were included in the study. There were 76 UKAs performed in female patients. The mean age was 65 ± 10 years and the mean body mass index was 28.6 ± 5 kg/m 2 . Patients with ‡15°of varus alignment preoperatively were excluded. Varus deformity was evaluated with use of the hip-knee-ankle angle (HKAA). Pre-arthritic/kinematic alignment was estimated with use of an arithmetic HKAA (aHKA, calculated as the medial proximal tibial angle minus the lateral distal femoral angle). We defined pre-arthritic/kinematic alignment as a postoperative HKAA within 3°of the aHKA. The primary outcome measures were the Knee Injury and Osteoarthritis Outcome Score (KOOS) Activities of Daily Living and Sport subscales, including the percentage of patients who met the patient acceptable symptom state (PASS) for these measures. Failure was defined as conversion to TKA.
Results:The mean follow-up was 10 years (range, 4 to 20 years), with a mean survival time estimate of 18.3 years (95% confidence interval [CI], 17.8 to 18.8). The rate of conversion to TKA was 3% (5 of 150 UKAs). Postoperatively, 127 (85%) of 150 knees were pre-arthritic/kinematically aligned, and 23 knees (15%) were not. Patients with compared to those without pre-arthritic/kinematically aligned knees had significantly longer mean survival (18.6 years; 95% CI, 18.2 to 19) compared with 15.4 years; 95% CI, 13.4 to 17.5, respectively; p = 0.008) and higher KOOS Activities of Daily Living (92 compared with 74; p < 0.001) and Sport subscale scores (74 compared with 36; p < 0.001). A greater proportion of knees in the pre-arthritic/kinematically aligned cohort met the PASS for the KOOS Activities of Daily Living (85%, 106 of 125 knees) and Sport subscales (109 of 125, 87%) compared with the non-pre-arthritic/kinematically aligned cohort (28% and 57%, respectively; p < 0.01).Conclusions: Pre-arthritic/kinematically aligned knees in this non-robotically assisted fixed-bearing medial UKA cohort had superior outcomes, including the KOOS Activities of Daily Living and Sport subscales and achievement of the PASS for these measures, compared with non-pre-arthritic/kinematically aligned at an average of 10 years after UKA. Knees that fell within 3°of a simple aHKA measurement on a 3-foot (1-m)-long standing radiograph had greater longevity and return to activities.Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Optimal alignmen...
“…In the present study, we investigated whether use of the pre-arthritic alignment angle would lead to favorable outcomes following UKA. Because of the general lack of agreement in the literature regarding the optimal postoperative alignment strategy in UKA, we retrospectively assessed patient data to find the pre-arthritic/kinematic alignment angle, as measured on 3-foot (1-m)-long standing radiographs with use of a simple arithmetic method 26,27 . We then assessed whether knees that had postoperative alignment within 3° of their pre-arthritic alignment showed superior results compared with knees that had postoperative alignment outside this range.…”
Background: The optimal alignment strategy in unicompartmental knee arthroplasty (UKA) is debated. Recent studies have suggested that kinematic alignment may lead to improved biomechanics and outcomes. The aim of the present study was to determine if pre-arthritic/kinematic alignment of knees would result in sustained long-term restoration of function, without conversion to total knee arthroplasty (TKA), following non-robotically assisted, fixed-bearing medial UKA.Methods: A total of 236 UKAs were performed from 2000 to 2015. Of these, a total of 150 medial UKAs met the inclusion criteria and were included in the study. There were 76 UKAs performed in female patients. The mean age was 65 ± 10 years and the mean body mass index was 28.6 ± 5 kg/m 2 . Patients with ‡15°of varus alignment preoperatively were excluded. Varus deformity was evaluated with use of the hip-knee-ankle angle (HKAA). Pre-arthritic/kinematic alignment was estimated with use of an arithmetic HKAA (aHKA, calculated as the medial proximal tibial angle minus the lateral distal femoral angle). We defined pre-arthritic/kinematic alignment as a postoperative HKAA within 3°of the aHKA. The primary outcome measures were the Knee Injury and Osteoarthritis Outcome Score (KOOS) Activities of Daily Living and Sport subscales, including the percentage of patients who met the patient acceptable symptom state (PASS) for these measures. Failure was defined as conversion to TKA.
Results:The mean follow-up was 10 years (range, 4 to 20 years), with a mean survival time estimate of 18.3 years (95% confidence interval [CI], 17.8 to 18.8). The rate of conversion to TKA was 3% (5 of 150 UKAs). Postoperatively, 127 (85%) of 150 knees were pre-arthritic/kinematically aligned, and 23 knees (15%) were not. Patients with compared to those without pre-arthritic/kinematically aligned knees had significantly longer mean survival (18.6 years; 95% CI, 18.2 to 19) compared with 15.4 years; 95% CI, 13.4 to 17.5, respectively; p = 0.008) and higher KOOS Activities of Daily Living (92 compared with 74; p < 0.001) and Sport subscale scores (74 compared with 36; p < 0.001). A greater proportion of knees in the pre-arthritic/kinematically aligned cohort met the PASS for the KOOS Activities of Daily Living (85%, 106 of 125 knees) and Sport subscales (109 of 125, 87%) compared with the non-pre-arthritic/kinematically aligned cohort (28% and 57%, respectively; p < 0.01).Conclusions: Pre-arthritic/kinematically aligned knees in this non-robotically assisted fixed-bearing medial UKA cohort had superior outcomes, including the KOOS Activities of Daily Living and Sport subscales and achievement of the PASS for these measures, compared with non-pre-arthritic/kinematically aligned at an average of 10 years after UKA. Knees that fell within 3°of a simple aHKA measurement on a 3-foot (1-m)-long standing radiograph had greater longevity and return to activities.Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Optimal alignmen...
“…We report being able to restore balance without the use of semi constrained inserts in all knees. Kostretzis et al reporting results after rTKA using restricted KA [14] found that in contrast to other studies using the Triathlon TS revision Knee System where TS inserts were used almost systematically in MA rTKA, the restricted KA rTKA protocol they used allowed most of the cases to be balanced with a standard PS insert (72%).…”
Section: Discussionmentioning
confidence: 91%
“…One study reported applying restricted KA principles to rTKA [14]. The authors allowed a limited amount of constitutional varus (<4 • ) in the reconstruction.…”
Background: Stiffness and mid-flexion instability (MFI) is a recognized complication of mechanically aligned (MA) total knee arthroplasty (TKA). Kinematic alignment (KA) has been proposed as a means by which to restore normal joint motion following TKA and potentially avoid stiffness and MFI. Several studies have documented improved function with KA when compared to MA. The aim of this study was to determine if revising MA TKAs failed for either MFI or stiffness into KA resolves MFI, achieves better range of motion, and improves clinical outcomes. Methods: A retrospective, single surgeon review was performed. All consecutive TKAs revised from MA into KA for MFI (def: >5 mm opening between 10° and 45° of flexion) or stiffness (def: flexion ≤90°) between January 2017 and May 2021 were included. The constitutional limb alignment of the operated knee was “reverse engineered” by measuring the coronal alignment of the contralateral healthy knee or pre-operative x-rays. Femoral Rotation was set at 3 degrees internal to the trans epicondylar axis. All coronal and sagittal angles were digitally measured on pre- and post-operative long leg and maximum flexion radiographs (minimum 12 month follow-up). The Knee Society Score (KSS) and range of motion assessments were collected preoperatively and at final follow-up. Comparisons between groups were done with a paired T test. Significance was set at p < 0.05. Results: Seven patients were included. Two were male, the mean age was 70.1 years (±9.3), mean follow-up was 32 months (±26). Three patients were revised for MFI and 4 for stiffness. Constitutional limb alignment was restored within 2 degrees for all patients. The mean total KSS gain was 65.9 (±18.1). The total KSS was significantly improved in all patients (p < 0.001). The mean maximum flexion gain was 30 deg (±23°) (p = 0.01). MFI was absent in all patients. Conclusion: In a limited series of patients, revision of stiff or unstable TKA from MA to KA resulted in improved range of motion by 30° on averages, resolved instability without the use of constrained liners, improved clinical outcomes with a mean gain of 75 points on the KSS, and restored constitutional limb alignment within 2 degrees in all patients. As these short term results are promising, further study is warranted.
“…In certain cases, intra-articular correction of the extra-articular deformity while simultaneously maintaining knee joint stability and soft tissue balance, is unattainable. For older and sedentary patients in that situation, a varus–valgus semi-constrained implant with supplemental short, cemented stems will be the simplest solution ( 51 ). If the patient is young and active, or a satisfactory result cannot be obtained with the above method, and/or a hinged implant is necessary, the authors’ preferred alternative would be to combine a correction osteotomy with a KA-TKA.…”
Section: Hybrid Techniquementioning
confidence: 99%
“…Then, the ideal option might be restoring the lower limb anatomy by addressing the extra-articular deformity through an osteotomy combined with KA-TKA ( Figs. 9 and 10 ) ( 51 , 52 ). Figure 9 Combined KA-TKA and femoral osteotomy at the level of the CORA for varus femoral deformity with associated sagittal and/or rotational deformity.…”
Over the years, with a better understanding of knee anatomy and biomechanics, superior implant designs, advanced surgical techniques, and the availability of precision tools such as robotics and navigation, a more personalized approach to total knee arthroplasty (TKA) has emerged.
In the presence of extra-articular deformities, performing personalized TKA can be more challenging and specific considerations are required, since one has to deal with an acquired pathological anatomy.
Performing personalized TKA surgery in patients with extra-articular deformities, the surgeon can: (1) resurface the joint, omitting the extra-articular deformity; (2) partially compensate the extra-articular deformity with intra-articular correction (hybrid technique), or (3) correct the extra-articular deformity combined with a joint resurfacing TKA (single stage or two-stage procedure).
Omitting the acquired lower limb malalignment by resurfacing the knee has the advantages of respecting the joint surface anatomy and preserving soft tissue laxities. On the other hand, it maintains pathological joint load and lower limb kinematics with potentially detrimental outcomes.
The hybrid technique can be performed in most cases. It circumvents complications associated with osteotomies and brings lower limb axes closer to native alignment. On the other hand, it creates some intra-articular imbalances, which may require soft tissue releases and/or constrained implants.
Correcting the extra-articular deformity (through an osteotomy) in conjunction with joint resurfacing TKA represents the only true kinematic alignment technique, as it aims to reproduce native knee laxity and overall lower limb axis.
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