Onlay Patellar Resurfacing in a Posterior-Stabilized Total Knee Arthroplasty Increases Patellar Crepitus Complication: A Randomized, Controlled Trial

BACKGROUND

Patellar crepitus (PC) is a potentially problematic complication after total knee arthroplasty (TKA) more commonly occurring with a posterior-stabilized (PS) prosthesis. Patellar resurfacing has been reported to reduce PC complications; however, no study has compared the PC complication rates between 2 different resurfacing techniques, namely inlay and onlay.

METHODS

A prospective, randomized controlled trial was conducted to compare the PC complication between inlay and onlay patellar resurfacing techniques. A total of 222 patients who underwent unilateral TKA using a Legion PS Total Knee System were randomized into 2 groups. PC incidence, time of PC presentation, radiographic parameters associated with PC development, and clinical outcomes were evaluated at 3, 6, 9, 12, 18, and 24 months postoperatively.

RESULTS

PC occurred significantly more in the onlay group (17.9% vs 6.5%, P = .009). Time of PC presentation in both groups was not different. Anterior knee pain was found in 11.5% of PC patients, and none required any surgical procedure. Postoperative radiographic parameters, range of motion, Knee Society score, Oxford score, patellar score, incidence and intensity of anterior knee pain, and visual analog scale of overall knee pain were not significantly different between the 2 groups during the follow-up period.

CONCLUSION

To reduce the chance of PC development, we suggest an inlay patellar resurfacing technique during PS-TKA with this knee system.

Comparison of clinical and radiographic results between total knee arthroplasties using medial pivot and posterior-stabilized prosthesis: A meta-analysis

OBJECTIVE

To evaluate the clinical and radiographic outcomes of total knee arthroplasties (TKA) between using medial-pivot (MP) and posterior-stabilized (PS) prosthesis. Does MP prosthesis and PS prosthesis influence the clinical results of a TKA?

METHODS

An electronic literature search of PubMed Medline and the Cochrane Library was performed from inception to October 1, 2019. A meta-analysis to compare postoperative outcomes of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Knee Society Score (KSS), range of motion (ROM), complications, and radiographic results between MP and PS prosthesis were conducted.

RESULTS

Seven eligible studies involving 934 adult patients (MP group, n = 461; PS group, n = 473) were identified for analysis. This study showed no significant difference between the 2 groups in the WOMAC scores, KSS, ROM, and complications (P > .05). The differences of the femorotibial angle, position of implant, and patellar tilt were also not significant between the 2 groups (P > .05).

CONCLUSION

The present meta-analysis has shown that patients with the MP prosthesis have similar clinical results as patients with PS prosthesis. Furthermore, the radiographic results, especially patella tilt angle, were also similar between the 2 groups. Therefore, surgeons should be aware that the types of prostheses are not a decisive factor to ensure successful operation.

Anterior Tibial Post Impingement During Stair Climbing: A Kinematic Analysis and Clinical Outcomes

BACKGROUND

Anterior tibial post impingement during gait and stair ambulation was reported in knees with posterior-stabilized prostheses. However, the link between anterior post impingement and knee kinematics and between anterior post impingement and the clinical outcome has not been well investigated. Therefore, the purpose of this study was to assess the anterior impingement to clarify the relevant kinematics and clinical results including patient-reported outcomes.

METHODS

We analyzed 40 well-functioning knees in 20 patients with a posterior-stabilized prosthesis due to osteoarthritis and who were followed up for 2 years or more. Dynamic lateral radiographs during stair-climbing activity were analyzed using a shape-matching technique, and anterior post impingement and the clinical outcome were assessed.

RESULTS

Anterior impingement of the tibial post was observed in 13 knees (33%) during the latter half of the stance phase and at the beginning of the swing phase with the average implant flexion angle of -2.4°. Implant flexion was significantly smaller, while the femoral component was located more posterior in the impingement knees. The posterior tibial slope was significantly greater in the impingement group (6.7° ± 2.0°, 5.3° ± 1.9°, respectively; P = .041); however, no significant differences were demonstrated in anteroposterior laxity and patient-derived assessments.

CONCLUSION

To avoid anterior post impingement, the posterior tibial slope should be made at 5° or less. Femoral notch-anterior post articulation should be designed to have good congruency in order to act as an anterior stabilizer in the case of impingement at knee extension.

The Effectiveness of Medial Femoral Epicondyle Up-Sliding Osteotomy to Correct Severe Valgus Deformity in Primary Total Knee Arthroplasty

BACKGROUND

While many surgical techniques can achieve neutral limb alignment and soft tissue balance in severe valgus deformity during total knee arthroplasty (TKA), few published reports concern medial femoral epicondyle up-sliding osteotomy.

METHODS

A prospective investigation was conducted of patients with severe valgus deformities who underwent medial femoral epicondyle up-sliding osteotomy. Clinical measurements, radiological evaluation, and complication data were recorded.

RESULTS

Using posterior-stabilized prostheses, 26 patients underwent 28 TKAs performed by the same surgeon using medial femoral epicondyle up-sliding osteotomy to balance the soft tissue. On average, the follow-up was 54 ± 18 months, and the patient age was 63 ± 11 years. All knees were type II according to Krackow's classification. Varus-valgus knee motion was prohibited with the protection of long-leg knee brace for 3 months. At the last follow-up, the Knee Society function score, Hospital for Special Surgery knee-rating scale, and range of motion were 94 ± 6, 91 ± 4, and 116° ± 8°, respectively. All knees were stable laterally, whereas 2 knees had mild medial laxity and the others were stable. The hip-knee-ankle angle, femorotibial angle, condylar-hip angle, plateau-ankle angle, and valgus angle were 179.9° ± 3.4°, 172.9° ± 3.6°, 89.8° ± 2.5°, 90.2° ± 1.1°, and 7.3° ± 3.5°, respectively.

CONCLUSION

Medial femoral epicondyle up-sliding osteotomy during TKA in patients with severe valgus deformities facilitates the restoration of lower limb alignment, soft tissue balance, and knee stability.