| The Surgical Technologist | AUGUST 2022 356 Kostretzis et al. Kinematic Alignment Total Knee Revision Case 2 A 75-year-old female was unsatisfied with the clinical results of her left TKA, 5 years after the surgery. There was a mid-flexion instability at clinical examination with a medial opening of 5 mm at 45◦ of flexion and a total ROM of 0–90◦. On radiographic examination (Figures 5A–D), there was an oversized tibia (lateral overhang), a lateral patellar retinaculum calcification, and, compared to the intact contralateral lower limb, the prosthetic knee was implanted with increased femoral varus (+4.0◦), decreased tibial varus (–5.5◦), and increased tibial posterior slope (+6◦). During revision surgery and after implant removal, to correct the mDFA by 5◦ and lower the elevated joint line, a 10mm distal medial femoral augment was used in combination with a 5-mm augment on the lateral side after a 2-mm refreshing cut. Posterior augments (5 mm) were used medially and laterally. The tibial bone surface was cut by removing 5 mm of anterior bone (none posteriorly, reducing the slope) and 5 mm medially to adjust varus/valgus orientation. With trial implants in place, the observed laxities (MCL 2 mm and LCL 3 mm) at 10◦ of flexion confirmed that we achieved our goals. With the patient’s bone anatomy, a 50 ×12-mm femoral stem and a short tibial stubby were cemented. A standard PS insert (13 mm) was selected (Figures 6A,B). At 53 months follow-up, the patient reported no pain and significantly improved with a WOMAC score of 13 and a ROM of 0–115◦. Case 3 A 76-year-old male with a painful left TKA 4 years after the surgery. At clinical examination, the knee had a flexion contracture of 15◦ and reached 90◦ of flexion. There was profound medial femoral and patellar pain upon palpation. On radiographic examination, compared to the intact contralateral lower limb, the right operated side was implanted with increased femoral valgus (+2◦), decreased tibial varus (−2.0◦), and reduced tibial posterior slope (−9.5◦, Figures 7A–D). In addition, the unresurfaced patella was subluxed and severely worn. Posterior femoral offset was estimated to be 5–7 mm shorter, and the femoral implant translated anteriorly. After implant removal, in addition to a refreshing cut, a supplemental 2-mm resection on the distal lateral condyle was performed to correct the mDFA by 2◦. To maintain the joint line, 5-mm distal augments were used on both condyles. To compensate for the posterior femoral condyles’ asymmetry of the implant in place (Genesis femur from Smith and Nephew has a thicker medial condyle), and to increase posterior femoral offset, we used a 10-mm posterior augment on the medial side and a 5-mm augment on the lateral side. Tibial bone surface was cut by removing 5 mm of anterior bone (none posteriorly, reducing the slope) and 2 mm medially to adjust varus/valgus orientation. With trial implants in place, the MCL laxity was 5 mm larger than LCL at 10◦ of flexion. This difference was hypothesized to be secondary to long-term tension on the MCL and subsequent stretching. In such a situation, we preferred to use a semi-constrained implant (Figures 8A–C). At 16 months follow-up, the patient reported having minimal pain and a ROM of 0–125◦. DISCUSSION The most important finding of the present study was that rKA principles can be safely used in revision TKA in the short- to midterm, thus supporting our hypothesis. At a mean 4 years’ followup, only one (2.3%) subject in our study required a reoperation for a polyethylene exchange. Most revision TKA cases included in this study had unsuccessful clinical results of the primary joint replacement (persisting pain, stiffness, instability, etc.). To improve patients’ function and satisfaction, the rKA protocol was used for revision TKA. In contrast to the studies listed in Table 7 where TS inserts were used almost systematically, the rKA protocol allowed most of our cases to be balanced with a standard PS insert (72%) and we obtained one of the lowest reoperation rates. The PROMs of revision knee arthroplasty using rKA in our study showed a WOMAC score of 34.4 (0–80, ±21.7) at the last follow-up. We also found that 14 (33%) patients reported persisting anterior knee pain after their revision surgery, even though we did not use a pain scale to quantify this finding. PROMs and satisfaction rates differ between primary and revision TKAs, with revision surgeries showing less improvement (4, 22). It is very difficult to evaluate the functional results of patients with revision TKA because of the high heterogeneity of the causes of failure. The primary operation has a substantial influence on the postoperative outcome of the revision. Baker et al. (4), analyzing data from the National Joint Registry for England and Wales (NJR) found the highest improvements in PROMs and satisfaction in cases where aseptic loosening was the cause and the lowest improvements when stiffness was the cause for revision. Greidanus et al. (22) studied 60 TKA revision surgeries and found a total WOMAC score of 30.9 at 2 years after surgery. Kasmire et al. (23) followed 175 patients who underwent revision TKA for aseptic failure and reported a total WOMAC score of 28.1 at 2 years’ follow-up. Notably, there is a paucity of literature regarding WOMAC scores for revision TKA at more than 2 years, and even though our scores do not show a superiority over the MA technique, we can assume that our WOMAC results would be at least comparable to projecting the results of the previous studies to a longer follow-up. Radiographic analysis in the present study showed no radiolucencies or signs of loose components. Therefore, standing coronal alignment was changed from 1.8◦ to 0.8◦ of aHKA varus to recreate the native knee anatomy set within the limits of rKA protocol. Our findings suggest that rKA used in revision TKA does not preclude good outcomes for revision arthroplasty. This study and the proposed rKA technique for revision TKA are not without limitations. First, to be eligible for a revision with the rKA protocol, a patient must be eligible to be revised with a short-cemented stem. If a longer stem with diaphyseal fixation is required, the longer stem may not be compatible with the patient’s anatomy and its restoration. Therefore, it is plausible that some of the more complicated revision cases with severe Frontiers in Surgery | www.frontiersin.org 8 August 2021 | Volume 8 | Article 721379
RkJQdWJsaXNoZXIy MTExMDc1