Is Mobile-Bearing Medial Unicompartmental Knee Arthroplasty Appropriate for Asian Patients With the Risk of Bearing Dislocation?

BACKGROUND: Mobile-bearing unicompartmental knee arthroplasty (UKA) is an attractive operation for medial unicompartmental knee arthritis, but unexpected bearing dislocation is a drawback. Bearing dislocation occurs more frequently in Asians, whose lifestyle involves deeper knee flexion than Westerners. This study investigated whether mobile-bearing medial UKA is appropriate for Asians by analyzing (1) the rate of bearing dislocation and (2) the results of patients with bearing dislocation. METHODS: We retrospectively reviewed 531 consecutive mobile-bearing medial UKA in the previous 15 years, including 22 patients with bearing dislocation who had at least 2 years of follow-up. The entire patient cohort was divided into 2 groups: the symmetrical bearing (187 knees) and the anatomic bearing (344 knees) groups. In the anatomic bearing group, patients who underwent surgery using the conventional phase III (283 knees) vs the Microplasty (61 knees) instrumentation systems were compared. RESULTS: The overall incidence of bearing dislocation was 4.1% (22/531). Patients with the symmetrical bearing displayed a relatively high dislocation rate of 9.6% (18/187), which significantly decreased to 1.1% (4/344) after changing to the anatomic bearing (P < .001). In the anatomic bearing group, the dislocation rate with the conventional phase III system was 1.4% (4/283). There were no bearing dislocations in the Microplasty system group (0%, 0/61) after at least 2 years of follow-up. CONCLUSION: Although mobile-bearing medial UKA was reported to have a high incidence of bearing dislocation in Asians, this frequency of dislocation is drastically decreased by bearing design and implantation system improvements. We consider mobile-bearing medial UKA appropriate for Asians.

Late Mobile-Bearing Dislocation in Unicompartmental Knee Arthroplasty.

The authors present 2 cases of late mobile-bearing dislocation after unicompartmental knee arthroplasty with long-term follow-up. Patients had anterior bearing dislocation more than 10 years after primary unicompartmental knee arthroplasty. Retrieved mobile bearings showed severe erosion on the posterior lip, suggesting frequent deep knee flexion as the cause of wear. Bearing dislocation is known to occur in the early postoperative phase. However, for Asians with a lifestyle that requires high knee flexion, dislocation might occur in the late postoperative phase. Such late bearing dislocation has a mechanism different from those reported in previous studies. Loss of bump in the posterior lip was found to be the cause. After late bearing dislocation, conversion to total knee arthroplasty is unnecessary because a simple bearing exchange will suffice. [Orthopedics. 2019; 42(1):e124-e127.].

Mid-Term Results of Oxford Medial Unicompartmental Knee Arthroplasty in Young Asian Patients Less than 60 Years of Age: A Minimum 5-Year Follow-up.

PURPOSE: The purpose of this study was to evaluate the efficacy of unicompartmental knee arthroplasty (UKA) in young active Asian patients by analyzing clinical outcomes, complications and survival rates. MATERIALS AND METHODS: Eighty-two knees were evaluated with a minimum follow-up of 5 years after Oxford phase 3 UKA in patients less than 60 years of age at the time of surgery. Their mean age was 54.7 years (range, 44 to 59 years). The mean follow-up period was 8.9 years (range, 5.3 to 12 years). Kaplan-Meier survivorship analysis was used to estimate implant survival. RESULTS: Including 3 bearing dislocations, 1 medial tibial collapse and 1 lateral osteoarthritis, the total complication rate was 6.1% (5/82). Of the 3 cases of bearing dislocation, 2 cases were resolved by replacing with a thicker bearing and 1 case was converted to total knee arthroplasty (TKA) due to repeated dislocation. The two knees with a medial tibial collapse and a lateral osteoarthritis were converted to TKA. The 10-year cumulative survival rate using Kaplan-Meier survival method was 94.7% (95% confidence interval: 88.7%-100%). CONCLUSIONS: Oxford medial UKA was reliable and effective in young active Asian patients providing good clinical results and survival rate in the mid-term follow-up.

Peri-articular injections of local anaesthesia can replace patient-controlled analgesia after total knee arthroplasty: a randomised controlled study.

PURPOSE: In recent years, there has been an increasing interest in peri-articular injections (PAI) to control post-operative pain after total knee arthroplasty (TKA). Previous studies have evaluated the effect of PAI using multimodal analgaesic protocols, but the concomitant use of patient-controlled analgesia (PCA) may has masked the genuine effects of PAI. We investigated the efficacy of PAI compared with PCA and determined whether conventional PCA can be effectively replaced with PAI after TKA. METHODS: Eighty patients undergoing unilateral TKA were randomised into two groups. The PCA group consisted of patients who used PCA after surgery, while the PAI group included patients who did not use PCA post-operatively but were given PAI during surgery. We measured changes in visual analogue scale (VAS) scores, straight leg raising (SLR), range of motion (ROM) and consumption of antiemetics or analgaesics. RESULTS: Pain levels in the PAI group were significantly lower than in the PCA group during two weeks post-operatively (p < 0.05).; functional recovery in the SLR test showed no difference between groups (p > 0.05).; mean ROM showed no difference; (p > 0.05) and there was no difference in the number of patients who needed additional analgaesics. However, antiemetic use was significantly lower for the PAI group (p < 0.05). CONCLUSIONS: PAI offered improved pain control and minimal side effects compared with PCA. Thus, PAI can replace conventional PCA for controlling post-operative pain after TKA.

Errata to "Coronal Alignment of the Lower Limb and the Incidence of Constitutional Varus Knee in Korean Females".

[This corrects the article on p. 49 in vol. 27, PMID: 25750894.].

Coronal alignment of the lower limb and the incidence of constitutional varus knee in korean females.

PURPOSE: In total knee arthroplasty (TKA), it is important to restore neutral mechanical alignment. The purpose of this study was to assess whether the lower limb alignment is neutral in healthy Korean females and investigate the incidence of constitutional varus knees among them. MATERIALS AND METHODS: Weight-bearing full-leg standing radiographs were obtained from 118 healthy females between the ages of 20 to 39 years. One radiologist and two orthopaedic surgeons measured the hip-knee-ankle angle (HKAA), medial proximal tibial angle (MPTA), and femoral anatomic mechanical angle (FAMA) on the radiographs and compared with the traditional gold standard HKAA of 0°, MPTA of 3° varus, and FAMA of 6°. RESULTS: The interobserver reliability of the three independent observers was high (p<0.001). The HKAA of the study subjects (1.35°±2.04°) was significantly different from the standard HKAA of 0° (p<0.001), but no statistically significant difference was observed in the MPTA (-3.18°±1.61°) and FAMA (5.99°±0.70°) from the standard values (p=0.083 and p=0.887, respectively). The incidence of constitutional varus alignment was 20.34%. CONCLUSIONS: In Korean females, the mechanical axis of the lower limb was not neutral and the incidence of constitutional varus alignment was slightly higher than that in Western females. We believe that these findings should be taken into consideration in planning reconstructive surgery of the knee, such as TKA, unicompartmental knee arthroplasty, and high tibial osteotomy.

Does the appearance of the patellofemoral joint at surgery influence the clinical result in medial unicompartmental knee arthroplasty?

The purpose of this study is to investigate the likelihood of unicompartmental knee arthroplasty (UKA) in patients with chondrosis in the patellofemoral joint. We evaluated the pain and functional changes in the patellofemoral joint of 62 patients who underwent medial UKA for medial compartmental osteoarthritis with symptoms in the patellofemoral joint. They were analyzed by the patellofemoral score of Lonner at postoperative 3months, 6months, 1year, and 2years prospectively. Preoperatively, the grade by total score was poor in all 62 cases, but it was improved to 36 excellent (58%), 16 good (26%), and 10 fair (16%), and there were no poor cases at 2years. The last follow-up showed satisfactory results in pain score, function score, and total score (p<0.05). Regarding this result, we believe chondrosis in the patellofemoral joint is not a contraindication to UKA, even in patients with patellofemoral joint symptoms.

Preventing lateral skin numbness after medial unicompartmental knee arthroplasty.

BACKGROUND: The authors report the results of preserving the infrapatellar branch of the saphenous nerve during unicompartmental knee arthroplasty to prevent lateral skin numbness. METHODS: All 100 cases had medial compartmental osteoarthritis and a minimally invasive technique had been used. The mean follow-up duration was two years and eight months (range, 24 to 42 months). RESULTS: The classification according to the location of this nerve was observed as either Mochida Type I with 76 cases (76%), Type II with 16 cases (16%), and unclassified type with 8 cases (8%). In Type I, the nerve was saved in 62 cases (82%), but could not be preserved in Type II because of the surgical procedure. These results showed that the mean distance from the joint line to the nerve of Type I was 9.13 mm (range, 4 to 15 mm) and the nerve passed inferiorly. CONCLUSIONS: This study showed the location of this nerve can be predicted ahead of the procedure, which will help preserve it during the surgery.

Early complications after minimally invasive mobile-bearing medial unicompartmental knee arthroplasty.

The purpose of this article is to review the early complications of minimally invasive mobile-bearing unicompartmental knee arthroplasty by analyzing the first 100 consecutive cases. All cases were medial unicompartmental arthroplasties with a follow-up of at least 24 months (range, 24-51 months). Seven revision procedures were performed due to 2 fractures of the medial tibial plateau, 1 loosening of the femoral component, and 4 dislocations of the meniscal bearing. The early results as determined by The Knee Society scores, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores and postoperative range of motion were satisfactory. However, there exists a high rate of early failures, which occurred during the initial learning curve. Therefore, surgeons must be aware that in order to minimize these complications, attention to detail is mandatory.

The role of hedgehog signaling during gastric regeneration.

BACKGROUND: Hedgehog signaling plays critical roles during embryonic development. It is also involved in tissue regeneration and carcinogenesis in various adult tissues. Moreover, it regulates the maintenance of cancer stem cells and adult stem cells. Although hedgehog signaling is important in gastric carcinogenesis, its role in gastric regeneration has not been previously examined. In the present study, we evaluated the expression and roles of hedgehog signaling during gastric regeneration. METHODS: Gastric ulcers were induced by serosal application of an acetic acid solution in mice. Sham-operated mice served as controls. The proliferation of gastric progenitor cells was studied using bromodeoxyuridine (BrdU). The expression of hedgehog signaling molecules and the differentiation of gastric progenitor cells were examined by immunohistochemical staining and Western blotting. RESULTS: One day after the induction of gastric ulcer, the proliferation of gastric progenitor cells increased; however, the expression of hedgehog signaling molecules, including sonic hedgehog (Shh), Indian hedgehog (Ihh), desert hedgehog (Dhh), and patched (Ptch1) decreased at the ulcer margin. From 5 days after the induction of gastric ulcer, newly generated gastric glands and their differentiation were observed at the ulcer margin. The expression of hedgehog signaling molecules gradually increased in the newly generated gastric glands of the ulcer margin. Cyclopamine, a specific inhibitor of hedgehog signaling, significantly inhibited the differentiation of mucous cells and parietal cells during the gastric regeneration process. CONCLUSION: The above results suggest that hedgehog signaling is involved in the differentiation of gastric progenitor cells during the gastric ulcer repair process.