Intra-operative findings in varus osteoarthritis of the knee. An analysis of pre-operative alignment in potential candidates for unicompartmental arthroplasty

Interest in unicompartmental knee arthroplasty (UKA) for the treatment of medial compartment osteoarthritis has increased in recent years with apparent improvement in the long-term results. This is a result of improved surgical technique, patient selection, and implant design. In an effort further to improve patient selection we analysed the relationship between the pre-operative alignment of the knee and the anatomical findings at the time of surgery. We compared these findings with the indications for UKA. From 4021 total knee arthroplasties we compared intra-operative observations with the pre-operative clinical data in order to identify knees with isolated, medial, compartment changes, which would have been ideal candidates for UKA. We found that only 247 of the knees (6.1%) met anatomical qualifications for isolated, medial, unicompartmental osteoarthritis, and of these, only 168 (4.3%) met clinical standards ideal for UKA. Preoperative alignment showed a significant relationship with patterns of disease. Logistic regression revealed a relationship between pre-operative alignment and intraoperative findings resembling a Gaussian distribution. Patients with a pre-operative varus alignment of 7 degrees were slightly more likely to be selected for UKA. But the further the anatomical alignment in either direction varies from 7 degrees of varus, the more unlikely it is for the knee to exhibit a disease pattern of isolated, medial, unicompartmental osteoarthritis.     

Minimally invasive surgical technique for unicondylar knee arthroplasty

Between August 1992 and December 1996, more than 700 unicondylar knee arthroplasty (UKA) procedures were done by the senior author (JA.R.), using well-defined patient selection criteria, which is paramount to the outcome of the procedure. The UKA procedure described is done through a smaller incision than that required for total knee arthroplasty (TKA) (3 inches versus 8 inches), thus minimizing blood loss (less than 200 mL), avoiding normal tissue sacrifice (opposite compartment, patellar bone, and cruciate ligaments), and decreasing morbidity (no patellofemoral disruption). The UKA costs less because it is done as an outpatient procedure in 80% of cases; since postoperative physical therapy is minimal or unnecessary, recovery time is shorter (90% independent function at 2 weeks after operation). Whereas TKA can have universal application, UKA is patient specific and cannot replace TKA in all circumstances. Likewise, the techniques for TKA and UKA are not interchangeable. However, with the use of well-defined patient populations and surgical techniques, the intermediate results of UKA have paralleled reported outcomes of TKA.     

Unicompartmental knee arthroplasty: a controversial history and a rationale for contemporary resurgence

Treatment of isolated compartment osteoarthritis with unicompartmental knee arthroplasty (UKA) has had mixed reported results and still remains a controversial procedure. More recently, adherence to more stringent patient selection criteria and refined surgical technique has resulted in improved clinical outcomes and survivorship. The popularization of UKA as a more tissue-sparing procedure and minimally invasive alternative to total knee arthroplasty has also played an integral role in its recent resurgence. This review details the history, evolution, and varied results of UKA. Many different prostheses have emerged, some with exceptional long-term results. Long-term prospective analyses will be critical in determining the role of UKA as a mainstay in the treatment of single compartment knee degenerative joint disease.     

The clinical outcome of revision knee replacement after unicompartmental knee arthroplasty versus primary total knee arthroplasty: 8–17 years follow-up study of 49 patients

When unicompartmental knee arthroplasty (UKA) failure occurs, a revision procedure to total knee arthroplasty (TKA) is often necessary. We compared the long-term results of this procedure to primary TKA and evaluated whether they are clinically comparable. Twenty-one patients underwent UKA conversion to TKA between 1991 and 2000. The results of these patients were compared to the group of 28 primary TKA patients with the same age, sex and operation time point. The long-term outcomes were evaluated using clinical and radiological analysis. The mean follow-up period of the patients was 10.5 years. The UKA revision patients were more dissatisfied, as measured by the WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) scale (0–100 mm) compared to the primary TKA patients (pain 18.1/7.8; p = 0.014; stiffness 25.7/14.4, p = 0.024; physical function 19.0/14.8, p = 0.62). Two patients were revised twice in the UKA revision group. There was one revision in the primary TKA group (p = 0.39). Improvement in range of motion (ROM) was better in the TKA patients compared to the UKA revision patients (8.2°/–2.6°, p = 0.0001). We suggest that UKA conversion to TKA is associated with poorer clinical outcome as compared to primary TKA.     

Lateral unicompartmental knee arthroplasty: A review

Isolated lateral compartment osteoarthritis of the knee is a rare condition affecting approximately 1% of the population, which is ten times less common than osteoarthritis affecting only the medial compartment. Unicompartmental knee arthroplasty(UKA) has many potential advantages over total knee arthroplasty. The benefits of UKA include a smaller incision, preservation of more native tissue(including cruciate ligaments and bone), decreased blood loss, and better overall proprioception. When UKA was first introduced in the 1970 s, the outcomes of medial UKA(MUKA) were poor, but the few cases of lateral UKA(LUKA) showed promise. Since that time, there has been a relative paucity of literature focused specifically on LUKA given it is a rare procedure. Refinements in patient selection criteria, implant design, and surgical technique have been made leading to increased popularity. A review of the recent literature reveals that LUKA is associated with excellent long-term clinical outcomes and implant survivorship when performed in properly selected patients. Implant design options include fixed vs mobile bearing as well as metal backed vs all polyethylene tibial component, with improved outcomes noted with fixed bearing designs. Three reasons cited for revision(i.e., fracture of the femoral component, fracture of the tibial component, and valgus malalignment) had been reported in past literature but not recently. Presently, while rare, the most common cause of failure and need for revision are osteoarthritis progression and aseptic loosening. Despite the need for an occasional revision procedure, the survivorship of LUKA is comparable to MUKA, although it should be noted that outcomes of MUKA have been notably varied. Continued pursuit of improved techniques and implant designs will continue to show LUKA to be an excellent procedure for appropriately indicatedpatients.     

Lateral unicondylar knee arthroplasty (UKA): Contemporary indications,surgical technique,and results

Unicompartmental femoro-tibial osteoarthritis usually affects the medial compartment of the knee, but in 10 %, the lateral compartment is primarily involved. Femoral osteotomy is attractive to avoid TKA in younger patients with low-grade unicompartmental osteoarthritis and a valgus deformity. However, only limited functional results can be expected for patients with Ahlback grade 2 or greater osteoarthritis. Moreover, because of previous skin incisions and hardware removal, TKA after femoral osteotomy remains a complex procedure with poor functional results. Unicompartmental knee arthroplasty for both the medial and the lateral compartments has been performed since the 1970s. In a patient with involvement of only one compartment, a medial or a lateral UKA can provide a quicker recovery and enhanced function when compared to TKA. In addition, it preserves bone stock and can be “easily” revised by a TKA. Technical improvements, combined with strict patient selection, have resulted in ten year survivorships greater than 90 %. However, lateral UKA is technically more challenging than medial UKA due to the lower number of indications, as well as the functional anatomy of the lateral compartment. The goals of this article are to present up-to-date information concerning indications, patients’ selection, surgical technique and results of lateral compartment UKA.     

The Repicci II<Superscript>®</Superscript> Unicondylar Knee Arthroplasty: 9-year Survivorship and Function

Background  

Unicompartmental knee arthroplasty (UKA) is a recognized procedure for treatment of medial compartment osteoarthritis. UKA using minimally invasive surgery (MIS) has the theoretical advantage of less bone resection and quicker rehabilitation. Whether the function of patients with UKA compares with that of patients with conventional TKA is unclear.     

Unicompartmental Knee Arthroplasty: More Conversions,Fewer Complications Than Proximal Tibial Osteotomy in a Young Population

BackgroundPatients with isolated medial compartment osteoarthritis requiring surgical intervention generally have two surgical options: unicompartmental knee arthroplasty (UKA) and proximal tibial osteotomy (PTO). Outcomes of reoperation rates and survivorship are important for counseling patients on treatment options.MethodsA retrospective, comparative cohort study was performed for a consecutive series of patients in the Military Health System who underwent either UKA or PTO between 2003 and 2018. All patients were between 18 and 55 years old and diagnosed with isolated medial compartmental arthritis. Cases with concurrent meniscal or cartilage procedures were included, while cases with concurrent ligament reconstruction were excluded. A minimum 2-year follow-up was required. The primary outcome was conversion to total knee arthroplasty, and the secondary outcome was reoperation for any reason.ResultsA total of 383 procedures were performed for isolated medial compartment arthritis in 303 patients (UKA 270, PTO 113). A multivariate analysis showed that PTO was associated with decreased risk of conversion to TKA compared to UKA (P = .0364). However, the reoperation due to complications was significantly higher in the PTO group (21.2% vs 2.2%; P ≤ .01). The 5-year conversion rate was 13.7% for UKA and 3.5% for PTO (P = .0033) with an average time to conversion of 3.1 years for UKA and 2.9 years for PTO (P = .7805).ConclusionsIn young patients with isolated medial compartment arthritis, conversion rates to TKA are higher with UKA compared to PTO. However, overall reoperation rate is higher with PTO, secondary to complications and revision procedures. Overall survivorship is acceptable for both procedures.     

Minimally invasive unicondylar arthroplasty: eight-year follow-up

This retrospective study reports the senior author's (J.A.R.) results with minimally invasive unicondylar knee arthroplasty (UKA). A total of 136 UKAs were performed in 1992 for the treatment of unicondylar osteoarthrosis. The surgical technique involves a limited medial parapatellar incision that reduces perioperative morbidity and bone preparation techniques that emphasize preservation of bone for future arthroplasty procedures. At 8 years, 4% of Ahlback stage 2 and 3 patients had undergone revision. Minimally invasive UKA provides a low morbidity alternative treatment for symptomatic medial compartment osteoarthritis.     

Two Year Follow-up of the Preservation Unicompartmental Knee Implant

Reported results of unicondylar knee arthroplasty (UKA) have mixed reviews in comparison with results of tri-compartmental knee arthroplasty (TKA). We prospectively evaluated the short-term results (2 years) of a newer design of a UKA implant (Preservation UKA) with a cobalt–chromium femoral component and an all polyethylene tibial component. Seventy-two patients with intact ligaments and loss of only medial articular cartilage received the Preservation prosthesis. Data were obtained using WOMAC, Knee Society score (KSS), and standard radiographs. WOMAC scores improved by 24 points and KSS improved by 33 points at 2-year follow-up. Mean flexion increased by 4° to126° at 2 years. On X-ray, only one patient had a radiolucency. No fractures occurred. Two knees were revised due to clinical symptoms of medial compartment pain. This 2-year follow-up study of the Preservation UKA shows promising early results. Long-term data would be necessary to compare results with TKA or other unicompartmental replacements.     

The mid-term clinical results of the phase 3 Oxford unicompartmental knee arthroplasty: a 6- to 8-year follow-up

Unicompartmental knee arthroplasty (UKA) is widely performed in the United Kingdom for the management of patients with symptomatic osteoarthritis of the medial compartment of the tibiofemoral joint. A limited number of papers have presented the findings of mid-term clinical and survival data with sufficiently large patient numbers following mobile-bearing UKA. The purpose of this study was to present the 6- to 8-year follow-up data on a series of 230 minimally invasive medial Oxford Phase 3 mobile-bearing UKAs in our institution. Data on surgical procedure, postoperative rehabilitation requirement, complications, revision procedures and Oxford Knee Score (OKS), Short Form-12 (SF-12) and visual analogue scale (VAS) pain scores were analysed. The results indicated that the majority of patient’s recoveries were uneventful, with 96% experiencing no postoperative complications. The mean OKS, VAS pain and SF-12 scores indicated good functional outcomes and acceptable perceived general health for this age group. Twenty-one patients underwent revision surgery, indicating a survival rate of 85% (95% CI: 0.76–0.91) during the 6- to 8-year follow-up period. The most frequently cited indication for revision was due to progression of osteoarthritis to the lateral component. To conclude, this series indicated that the mobile-bearing Oxford UKA provides good clinical outcomes at 6- to 8-year follow-up, with minimal requirement for postoperative rehabilitation, few complications and an acceptable survivorship in the mid-term.     

Which do patients prefer,unicompartmental or total knee arthroplasty?

Objective

Unicompartmental knee arthroplasty (UKA) is a viable option for relieving pain and improving function in patients with isolated compartment knee osteoarthritis (OA). Certain surgeons prefer total knee arthroplasty (TKA) over UKA even when patients are candidates for UKA. Therefore, the decision to perform a UKA or a TKA when both are indicated is not straightforward. The goal of this study was to compare pre-operative and post-operative patient-reported outcome (PRO) scores for patients who underwent both a UKA and a contralateral TKA.

5- to 16-year follow-up of 54 consecutive lateral unicondylar knee arthroplasties with a fixed-all polyethylene bearing

The clinical and radiographic results of 54 knees (52 patients) with a unicondylar knee arthroplasty (UKA) with fixed-all polyethylene bearing implanted for lateral osteoarthritis were studied at 5- to 16-year follow-up (mean, 100.9 months). Four underwent second surgery: 1 conversion to total knee arthroplasty and 3 received UKA in the medial compartment. The mean International Knee Society knee score was 94.9 points, with a mean range of motion of 132.6° and a mean International Knee Society function score totaling 81.8 points. Implant survival was 98.08% at 10 years. These excellent results suggest that UKA with fixed-all polyethylene bearing is a reliable option for management of isolated lateral knee osteoarthritis.     

混合型单髁与全膝关节置换治疗膝内侧间室骨关节炎的疗效比较

目的：探讨Oxford第3代混合型单髁置换（unicompartmental knee arthroplasty,UKA）与全膝关节置换（total knee arthroplasty,TKA）治疗膝关节内侧间室骨关节炎的疗效。方法：回顾性分析2017年10月至2019年10月行膝关节置换术的156例患者,男44例,女112例,年龄50~75（58.76±4.97）岁。根据不同治疗方式分为单侧TKA组和单侧Oxford第3代混合型UKA组。单侧TKA 81例（81膝）,男23例,女58例,年龄51~75（58.60±5.01）岁;单侧Oxford第3代混合型UKA 75例（75膝）,男21例,女54例,年龄50~72（58.92±4.95）岁。比较两组临床评估指标,包括手术一般情况、相关并发症、美国膝关节协会评分（American Knee Society score,AKSS）临床评分和功能评分;影像评估指标包括髋膝踝角（hip-knee-ankle angle,HKA）、股骨假体内外翻角（femoral component valgus/varus angle,FCVA）、股骨假体后倾角（femoral component posterior slope angle,FCPSA）、胫骨假体内外翻角（tibial component valgus/varus angle,TCVA）、胫骨假体后倾角（tibial component posterior slope angle,TCPSA）,是否发生膝关节外侧间室进展、衬垫脱位、假体下沉、松动。结果：UKA组术中出血量、手术时间、住院天数均显著优于TKA组（P<0.05）,两组术后均未出现并发症。两组患者均获随访,时间24~54（38.01±8.90）个月。末次随访两组AKSS临床评分、功能评分、HKA均优于术前（P<0.05）。末次随访UKA组AKSS临床评分、功能评分均优于TKA组（P<0.05）,TKA组HKA优于UKA组（P<0.05）。末次随访两组TCVA、FCVA差异无统计学意义（P>0.05）,UKA组TCPSA、FCPSA大于TKA组（P<0.05）,UKA组未出现外侧室进展。结论：Oxford第3代混合型UKA治疗膝关节内侧间室骨关节炎,较TKA具有手术创伤小、失血量少、手术时间短、住院时间短、术后快速康复、膝关节功能恢复更好等优势,疗效满意。     

固定平台单髁置换术治疗膝关节内侧骨关节炎

目的：探讨采用固定平台假体膝关节单髁置换术治疗膝关节内侧单间室骨性关节炎的早期临床疗效。方法：自2015年1月至2017年12月,采用固定平台单髁置换术治疗62例膝关节内侧间室骨性关节炎患者,其中男19例,女43例;年龄47~83（65.3±8.2）岁;病程5~72（19.4±14.3）个月。观察术后并发症情况,并采用VAS评分评价疼痛缓解程度,HSS膝关节评分评价临床疗效。结果：62例患者均获得随访,时间4~40（19.9±10.2）个月。所有患者切口愈合良好,无须术后输血,住院时间2~10（3.5±1.6） d。术后未发生脱位、感染、松动或假体周围骨折等并发症,1例患者术后1个月并发胫后静脉血栓。HSS评分由术前的69.9±7.2提高至末次随访时的90.1±7.4;其中优51例,良9例,可2例;VAS评分由术前的3.8±0.9降至末次随访时的1.1±0.9。结论：固定平台单髁关节置换术治疗膝关节内侧单间室骨性关节炎术后住院时间短,并发症低,可以获得较好的早期临床疗效。     

Posterior dislocation of meniscal bearing insert in mobile bearing unicompartmental knee arthroplasty mimicking a Baker cyst

Unicompartmental knee arthroplasty (UKA) is a well-established procedure for isolated medial compartment osteoarthritis. Meniscal dislocation is a well-recognized complication in mobile bearing UKA especially when performed for the lateral compartment. Dislocation in medial UKA is relatively uncommon and is usually anterior when encountered. We would like to report a case of posterior dislocation of the bearing insert in a mobile bearing medial UKA presenting as a Baker cyst, which was subsequently revised to total knee arthroplasty.     

Patterns of Compartment Involvement in End‐stage Knee Osteoarthritis in a Chinese Orthopedic Center: Implications for Implant Choice

Objectives

Knee osteoarthritis (OA) is a prevalent disease in the elderly, causing pain and contributing to poor quality of life. Surgical intervention, such as knee arthroplasty, can be used in those with end‐stage knee OA. Total knee arthroplasty (TKA) is one of the most common surgical procedures for end‐stage knee OA, with promising clinical outcomes. However, a large proportion of patients with isolated compartment OA can be treated with unicompartmental knee arthroplasty (UKA) instead. UKA has shown better patient‐reported functional outcomes, and lower mortality and major complication rates than TKA. The percentage of UKA in knee arthroplasty varied in different orthopedic centers, and we believed that the requirement for UKA was underestimated in many centers. A retrospective study was carried out on our Chinese patient population presenting for knee arthroplasty; it aimed to identify the proportion of patients that might be suitable for UKA.

Methods

A retrospective cross‐sectional study of 155 consecutive patients (168 knees) awaiting TKA for end‐stage primary OA was performed. The pattern and grade of OA was recorded from preoperative weight‐bearing anteroposterior and non‐weight‐bearing lateral radiographs. The medial, lateral, patellofemoral compartment was given an individual Kellgren–Lawrence grade on the radiographs, and those grade ≥3 were defined as end‐stage OA. The compartments involvement was established then. The integrity of the anterior cruciate ligament (ACL) was determined by the modified Keyes classification on lateral radiographs. The applicability for total or partial knee arthroplasty was determined according to the compartments involvement.

Results

Medial compartment involvement was found in 154 (91.7%) knees, while the involvement of the lateral compartment and patellofemoral joint was found in 54 (32.1%) and 57 (33.9%) knees, respectively. Eighty‐one (48.2%) of the knees showed medial compartment OA with or without patellofemoral joint involvement, and modified Keyes classification grade 1, indicating an intact ACL, and, hence, potential suitability for medial UKA. Isolated lateral OA indicating possible suitability for lateral UKA was identified in 11 knees (6.5%). No patients showed isolated patellofemoral joint OA. The other 76 (45.2%) knees could be treated by TKA.

Conclusions

The medial compartment was the most commonly affected in our Chinese patients indicated for knee arthroplasty. More than half of the patients in this group could be treated by either medial or lateral UKA.

     

Unicompartmental Knee Arthroplasty Provides Significantly Greater Improvement in Function than Total Knee Arthroplasty Despite Equivalent Satisfaction for Isolated Medial Compartment Osteoarthritis

BackgroundWhile some advocate for unicompartmental knee arthroplasty (UKA) for isolated medial compartment osteoarthritis (OA), others favor total knee arthroplasty (TKA). The purpose of this study was to compare the functional outcomes of UKA and TKA performed for patients with unicompartmental arthritis (OA).MethodsA study was performed on 133 patients that met strict criteria for UKA, but who underwent either medial UKA or TKA for isolated medial compartment OA based upon physician equipoise. The primary outcome—New Knee Society Score (KSS)—was assessed preoperatively and at 2 years postoperatively. A propensity score weighted regression was used to balance the groups on several key covariates, including age, gender, body mass index, and baseline KSS.ResultsAfter propensity weighting, there were no significant differences between UKA and TKA in overall baseline KSS or KSS after 2 years postoperatively. While TKA patients had demonstrated a significantly greater improvement in the symptoms KSS subscale, UKA patients had a significantly greater improvement in the function subscale. Expectations were significantly more likely to be met after UKA, but there were no differences in patient satisfaction.ConclusionUKA and TKA are both highly successful options for treating patients with medial compartment OA, although functionality increased more, and expectations were more likely to be met, after UKA in this study. Given equivalent patient satisfaction after both TKA and UKA, surgeons should consider factors such as clinical experience, individual preference, cost of care, surgical risk, and recovery needs, when making treatment decisions regarding this clinical entity.     

单髁置换术与胫骨高位截骨术治疗膝关节内侧间室骨关节炎的Meta分析

目的:用Meta分析的方法对国内外已发表较高质量的有关比较胫骨高位截骨治疗(HTO)与单髁置换治疗(UKA)内侧间室骨关节炎患者的临床疗效进行综合定量分析,为内侧间室骨关节炎患者提供一种较好的外科选择方法。方法:计算机检索Cochrane图书馆(2017年6期)、PubMed、Ovid、ELSIVE、CNKI及万方等数据库。检索1970年1月1日至2017年6月30日有关胫骨高位截骨治疗(HTO)与单髁置换治疗(UKA)内侧间室骨关节炎患者包括并发症、膝关节评分、膝关节活动度、翻修率及优良率等文献,筛选出符合纳入标准的文献,并对其进行严格的质量评价。利用Cochrane协作网提供的RevMan 5.0软件对纳入研究结果进行Meta分析,并对数据进行异质性检验。结果:符合纳入标准的文献13篇,总样本量1 043例。其中HTO治疗组462例,UKA治疗组581例。HTO治疗组与UKA治疗组进行比较,两组在对侧间室关节退变率[WMD=3.21,95%CI (1.13,9.10)],膝关节活动度(ROM)[WMD=6.55,95%CI(1.44,11.66)],膝关节Lysholm评分[WMD=-3.15,95%CI(-4.77,-1.53)],并发症[WMD=2.78,95%CI(1.52,5.11)],翻修率[WMD=1.81,95%,CI (1.17,2.80)],优良率[WMD=0.49,95%CI (0.30,0.80)],胫股角度改变(FTA)[WMD=-2.37,95%CI(-3.63,-1.11)]有明显差异(P0.05);HTO治疗组与UKA治疗组在髌股关节退变率[WMD=1.59,95%CI(0.65,3.84)]及膝关节运动速度[WMD=-0.02,95%CI(-0.09,0.04)]中无明显差异(P0.05)。结论:基于有限的资料,在中短期临床效果比较中,胫骨高位截骨术治疗内侧间室骨关节炎患者是一种比较好的选择方式,而长期临床效果可能需进一步研究。