Is simultaneous bilateral unicompartmental knee arthroplasty and total knee arthroplasty better than simultaneous bilateral total knee arthroplasty?

INTRODUCTION: This retrospective study aims to clarify if there are benefits of performing unicompartmental knee arthroplasty (UKA) on just one indicated side in patients who undergo simultaneous bilateral knee arthroplasty. MATERIALS AND METHODS: We compared 33 cases of simultaneous bilateral UKA/total knee arthroplasty (TKA) (S-UT) with 99 cases of simultaneous bilateral TKA (S-TT). Comparison included blood tests [C-reactive protein (CRP), albumin, and D-dimer], the incidence of deep vein thrombosis (DVT), range of motion (ROM), and clinical scores before and 1 year after surgery. RESULTS: Clinical scores were not significantly different between the groups. The postoperative flexion angle was significantly better in UKA sides. Blood tests showed that the S-UT had a significantly higher albumin value at 4 and 7 days after surgery. The CRP value at 4 and 7 days, and the D-dimer value at 7 and 14 days after surgery were significantly lower in the S-UT. The S-UT had significantly lower incidence of DVT. CONCLUSIONS: In cases of bilateral arthroplasty, if there is an indication on only one side, a better flexion angle can be obtained by UKA on that side, and with less surgical invasion. Moreover, the incidence of DVT is low, which is considered to be a benefit of performing UKA on just one side.

Trans patellar tendon sagittal tibial cut for lateral unicompartmental knee arthroplasty-location of the split- CT simulation study.

BACKGROUND: In lateral unicompartmental knee arthroplasty (UKA), a sagittal cut is often performed through the patellar tendon (PT). Although the approach is likely widely used, it has not been described in detail, especially regarding the site of the split. This study aimed to clarify where the split should be made. METHODS: This single-center retrospective cohort study included 49 consecutive patients and 51 knees with lateral osteoarthritis. Using preoperative computed tomography, we measured the distance from the medial edge of the PT to the intersection of the PT and the sagittal cutting line, defined as a line parallel to the Akagi's line and passing the tip of the lateral tibial spine. RESULTS: The sagittal cut line passed a mean of 45 ± 11% of the patellar tendon width from the PT medial edge. CONCLUSIONS: The tendon split should be made just medial to the center of the PT because it is where the sagittal cut line for lateral UKA passes.

Is postoperative flexion angle genuinely better in unicompartmental knee arthroplasty than in total knee arthroplasty? A comparison between the knees in the same patients.

BACKGROUND: The aim of this retrospective study was to clarify if unicompartmental knee arthroplasty (UKA) can acquire a greater postoperative flexion angle than total knee arthroplasty (TKA) in the same individuals after adjusting for the preoperative flexion angle and if the preoperative flexion angle correlates with the change in flexion postoperatively. METHODS: Thirty-five patients between 2011 and 2017 who had undergone simultaneous TKA on one knee and UKA on the other knee were included in the study. Range of motion was measured preoperatively and at one year after the surgery. The relationship between the pre- and postoperative flexion angles was evaluated. RESULTS: UKA can acquire approximately 10° greater flexion postoperatively when compared to TKA, even after adjustment for the preoperative flexion angle. The preoperative flexion angle is strongly and negatively correlated with the change in flexion angle in both the TKA and UKA knees. A preoperative knee with a smaller flexion angle will gain greater flexion postoperatively, whereas a preoperative knee with a greater flexion angle tends to lose flexion angle. The thresholds of gain/loss are estimated as 123° and 135° in TKA and UKA knees, respectively. CONCLUSIONS: These results provide an evidence that the UKA can acquire a greater postoperative flexion angle than the TKA and valuable information for patients who demand a deep postoperative flexion angle.

The tibial lateral axis is a novel extraarticular landmark for detection of the tibial anteroposterior axis.

PURPOSE: Although the tibial rotation axis is significant in knee arthroplasty, no reliable extraarticular landmark has been proposed. We hypothesized that the tibial lateral axis (TLA), a tangential line of the lateral tibial surface, is perpendicular to the surgical epicondylar axis (SEA) and compared it to other existing landmarks by 3D-CT. METHODS: Fifty legs in 25 consecutive patients were studied. Using their preoperative CT, the TLAs were identified on slices at 10-50% of the total length of the tibia and the measured differences of angles against the line perpendicular to the SEA (the tibial AP axis) were calculated. The differences between the SEA and the femoral and tibial posterior condylar axis, Akagi's line and the line between the medial intercondylar spine and the medial border of the patellar tendon (sAP line)(intraarticular), the ankle axis, and the transmalleolar axis (extraarticular) were also calculated and compared. RESULTS: The mean values of TLA at 10%, 20%, 30% were virtually parallel to the SEA (0.97° ± 4.84°, 0.02° ± 4.61°, 1.10° ± 4.97°, respectively). They were equivalent to existing intraarticular landmarks and superior to existing extraarticular landmarks, and these levels corresponded to the tip to the lower end of the tibial tubercle (at 10.8% and 17.0% of total tibial length). CONCLUSION: The proximal TLAs can be an extraarticular bony landmark that indicates the line perpendicular to the SEA. A prospective study is needed to prove the validity and accuracy of the axes clinically.

A subcutaneous arthroscopic portal closure technique without thread exposure.

We present a simple new suture technique for an arthroscopic portal that enables a secured subcutaneous suture without thread exposure. A curved suture needle is inserted through the skin at approximately 1 cm from the wound edge. The needle penetrates the subcutaneous tissue and exits through the skin on the opposite side of the wound edge. The needle and suture are pulled from just underneath the skin layer. The thread is collected within the wound, and the other end of the thread is pulled from the wound. The needle is inserted at just beneath the skin layer, penetrates the subcutaneous tissue, and pierces the opposite side of the skin. The needle is retrieved along with the thread at approximately 1 cm from the other side of the wound edge. After removing the needle from the thread, the thread passing in the wound is located and the needle side of the thread is retrieved from the wound. The ends of the thread are tied under the appropriate tension. From our findings, we recommend this method for suturing of all arthroscopic portals, as well as other small incisions that need water-tight suture.

A Modified Under-Vastus Approach for Knee Arthroplasty with Anatomical Repair of Soft Tissue.

The under-vastus approach (UVA) is a modification of the conventional subvastus approach for knee arthroplasty. Our modified UVA allows the muscles to be spared while offering good exposure of the operative field and facilitating anatomical repair of the capsule and fascia. A medial parapatellar incision is made and the vastus medialis fascia is incised along the same line. The muscle belly is not incised but detached from the surrounding fascia and retracted laterally. The suprapatellar pouch capsule is then laterally incised under the vastus muscles. The patella can then be easily retracted laterally and adequate exposure is possible. After the procedure, both capsule and fascia can be anatomically repaired. We use this approach for all primary arthroplasties in our practice. There has been no case in which an additional muscle incision was required, and there were no intraoperative complications. The modified UVA allows for excellent exposure of the operative field as well as muscle retention in both primary total and unicompartmental knee arthroplasties.