Stepwise treatment strategy for spontaneous osteonecrosis of the medial femoral condyle of the knee joint

doi:10.12307/2024.029

Abstract

Abstract: BACKGROUND: Currently, there have been a variety of conservative and surgical treatment plans for spontaneous osteonecrosis of the knee, achieving excellent results. However, a broad consensus on indication and guide of surgical treatment has not been announced. In clinical practice, there is still a misunderstanding that unicondylar replacement or total knee arthroplasty should be performed upon the discovery of spontaneous osteonecrosis of the knee, while an urgent need for universal access to the concept of stepwise therapy.
OBJECTIVE: To summarize and find the factors leading to the poor effect of conservative treatment in spontaneous osteonecrosis of the knee, which occurred on the medial femoral condyle, from the literature and clinical cases, at the same time, combined with the Koshino stage, to propose the strategy of stepwise spontaneous osteonecrosis of the knee treatment on the medial femoral condyle.
METHODS: A systematic search of the literature database was conducted to summarize the factors leading to poor outcomes of conservative treatment in spontaneous osteonecrosis of the medial femoral condyle. Meanwhile, according to the Clinical & Health Records for analytics & Sharing system, the cases receiving conservative and surgical treatment in spontaneous osteonecrosis of the medial femoral condyle in the Department of Orthopedics of Guangdong Provincial Hospital of Chinese Medicine from January 2017 to January 2023 were analyzed retrospectively, then the causes of success and failure in typical cases were summarized and analyzed.
RESULTS AND CONCLUSION: (1) Early diagnosis and treatment of spontaneous osteonecrosis of the knee were very important for prognosis. For sudden knee pain in some patients, if no obvious abnormality was found in the X-ray examination, and the symptoms persisted and could not be relieved for more than 1 week, an MRI examination was recommended to detect early spontaneous osteonecrosis of the knee. (2) The X-ray images of Koshino stage 1 and stage 2 of spontaneous osteonecrosis of the medial femoral condyle were difficult to be distinguished, which needed to be probed by MRI. MRI images of Koshino stage 1 were mainly characterized by bone marrow edema, and an osteonecrosis area with a clear boundary was not formed, while MR images of Koshino stage 2 showed a necrotic area with a clear boundary. (3) Five factors leading to the poor effect of conservative treatment on spontaneous osteonecrosis of the medial femoral condyle were summarized: a. The necrotic area was > 5 cm2; b. The necrotic area accounted for more than 40% of the condyle; c. relative compression percentage of medial meniscus ≥33% (with or without medial meniscus injury and subchondral bone marrow edema); d. MRI depth of necrotic area (anterior-posterior diameter of sagittal necrotic area) > 20 mm; e. varus deformity of lower limb >6°. (4) Conservative treatment of spontaneous osteonecrosis of the knee in Koshino stage 1 was good. For spontaneous osteonecrosis of the knee in Koshino stage 2, conservative treatment was preferred or combined with drilling decompression. If there was no relief or improvement of symptoms or in MRI after 3 months, while the patient had any of the previous five factors, then knee preservation surgery should be considered. For spontaneous osteonecrosis of the knee in Koshino stage 3 and stage 4, knee preservation surgery should be selected based on the previous five factors, including age, gender and activity level of the patient. Total knee arthroplasty was used for spontaneous osteonecrosis in Koshino stage 4, which was associated with symptomatic patellofemoral arthritis, valgus alignment, or necrotic area, which greatly affected the stability of unicondyle prosthesis.

Key words: spontaneous osteonecrosis of the knee, subchondral insufficiency fractures of the knee, medial meniscus protrusion, meniscus injury, stepwise treatment strategy

CLC Number:

Pan Jianke, Yang Meiping, Han Yanhong, Zhao Di, Huang Hetao, Cao Houran, Liu Jun, Luo Minghui, Li Xiang, Chen Hongyun, Yang Weiyi. Stepwise treatment strategy for spontaneous osteonecrosis of the medial femoral condyle of the knee joint[J]. Chinese Journal of Tissue Engineering Research, 2024, 28(12): 1907-1913.

Figures/Tables 12

(1)内侧半月板损伤：最早NORMAN等[3]于1978年利用关节造影检查 27个SONK膝关节中有21个 (78%) 半月板撕裂，提出内侧半月板碎片边缘的应力集中可能导致股骨髁缺血性坏死，老年患者通过关节造影早期发现内侧半月板撕裂并及时治疗，对于避免“自发性”骨坏死的晚期变化可能很重要。HUSSAIN等[6]纳入26篇关于SONK病因分析的文献，26 篇文献中有 21 篇(80.7%)涉及半月板在SONK发展中的作用，SONK与半月板撕裂或半月板切除术后的发展有关，以内侧半月板撕裂、后根撕裂最为常见。ROBERTSON等[5]通过MRI及关节镜检查，发现在SONK患者中常可合并内侧半月板后根部的撕裂，该发生率可达到80%(24/30)，15 例完全撕裂，9例部分撕裂，提出SONK可能与内侧半月板后根部撕裂后，导致股骨负重区的应力集中、软骨下骨髓水肿有关。FUJISAWA等[13]是对98例诊断为股骨内侧髁SONK患者的102膝进行了内侧开放楔形胫骨高位截骨术 (high tibial osteotomy，HTO)，发现所有病例均有内侧半月板撕裂，包括2个退化、2个水平撕裂、40个放射状撕裂、4个复杂撕裂和54个内侧半月板后根撕裂，99%(101/102)的膝关节内侧半月板突出超过3 mm；SONK病例半月板撕裂率较高，导致环向应变中断，如内侧半月板后根撕裂(52.9%)或放射状撕裂(39.2%)，内侧半月板突出的严重程度与SONK体积显著正相关(P < 0.001)。SUNG等[14]观察半月板损伤类型对SONK的影响：内侧半月板后根部撕裂组的半月板突出率为46.1%，平均坏死面积为423.1 mm2，内侧半月板后角水平裂组的半月板突出率为35.3%，平均坏死面积为175.8 mm2；与内侧半月板后角水平撕裂相比，后根撕裂将导致更大程度的突出和更广泛的骨坏死。 (2)内侧半月板突出：ODA等[15]发现100%(104)SONK患者中都存在内侧半月板突出，4 个SONK在发病前因膝关节疼痛体检发现内侧半月板突出，几个月后通过MRI检查显示存在SONK，提出内侧半月板突出是SONK的病因之一，内侧半月板突出的进展可能与SONK的发展有关。刘新光等[12]通过病例回顾发现SONK患者中内侧半月板突出(94.1%)和半脱位(52.9%)的发生率高，提出内侧半月板突出与 SONK 的发生有关，而且突出长度与骨坏死体积呈正相关。而膝内翻、内侧半月板根部撕裂是造成内侧半月板突出的主要危险因素[16]。HASHIMOTO等[17]随访78例SONK患者1年，其中48例行单髁置换术，30例保守治疗成功，通过患者发病3个月内的膝关节MR测量内侧半月板突出的绝对值(a)和内侧半月板突出相对百分比(挤压出胫骨平台半月板的宽度a与整个半月板宽度b相比的百分率，图2)，发现单髁置换组内侧半月板突出(P=0.001)、相对突出百分比(P=0.001)及放射状撕裂发生率(P=0.021)均高于保守组，相对突出百分比是SONK患者发病后1年内行单髁置换的预测因子，相对突出百分比33%的患者是SONK进展的高危人群，早期(发病3个月内)内侧半月板相对挤压百分比≥33%是SONK 发病1年后预后不良的预测指标。"

(3)下肢力线内翻畸形：AKAMATSU等[18]对分别进行保守和手术治疗的两组SONK患者(n=27膝)随访1年，发现手术组的股胫角明显大于保守组的股胫角，提出股胫角> 180°(下肢力线内翻> 6°)预示着该早期SONK患者保守治疗效果欠佳。GOSHIMA等[19]报道12例患者接受开放楔HTO治疗胫骨内侧平台SONK，其手术指佂为：①症状性骨关节炎和内侧间室的骨坏死；②存在内翻畸形(股胫角> 176°/下肢力线内翻> 2°)；③活跃患者(没有年龄限制)，其中11例仅胫骨内侧坏死，1例同时股骨和胫骨坏死，9例患者(75%)观察到有半月板后根撕裂，3例有水平撕裂，所有患者均有内侧半月板外突，术后所有患者膝关节活动度和临床评分皆获得显著改善，11例患者在取出钢板时接受二次关节镜检查时有9例(81.8%)观察到软骨再生。TSUKAMOTO等[4]分析Kellgren-Lawrence 1级或2级的SONK组(31膝)、骨关节炎组(32膝)病例资料，发现SONK组胫骨近端内侧角畸形(85.25±1.58)°比骨关节炎组(83.76±2.37)°更大(P=0.005)，SONK组关节线会聚角(2.50±1.67)°显著大于骨关节炎组(1.66±1.39)°，SONK软骨下坏死区域的大小受胫骨近端内翻畸形的影响(呈负相关)，胫骨近端内翻畸形和存在关节线会聚角有助于诱发SONK，提出胫骨近端内侧角小于84°伴有急性膝关节疼痛应尽快MRI检查。正常的膝关节线是平行的，关节线会聚角为0°，关节线会聚角的存在将引起间隙狭窄处间室的关节软骨过大的剪切应力。NAKAYAMA等[20]使用有限元模型分析发现，与正常膝关节线相比，如果关节线会聚角为5°，对关节软骨的剪切应力增加1.5倍，如果关节线会聚角为10°，剪切力增加2倍。 2.2 临床分期最常用的分期方法是1979年Koshino分期[21- 22]，见表1。Koshino分期基于临床和正位X射线影像学的结果，将SONK分为4个阶段。Koshino 1期和2期的影像在X射线片下较难区分，作者认为临床实际工作中可借助MR检查图像进行区分，Koshino1期MR图像主要以骨髓水肿为主，尚未形成边界清晰的骨坏死区(如Case1)，而Koshino 2期MR上可见边界清晰的坏死区(如Case2，Case3，Case4)。此外，AGLIETTI等[23]对Koshino分期法进行了修改，将Koshino分期法的3，4期进一步细分，共分为5期。一些学者还参考继发性骨坏死的分期方法Mont分期和改良股骨头坏死的分期方法Ficat分期来对SONK进行分期[24-25]。"

2.3 X射线检查对坏死区域的评估及对预后的影响 MUHEIM等[26]率先提出测量正位X射线片坏死区域长度A和侧位X射线片病变长度B，二者乘积为坏死区域面积大小，小于3.5 cm2的小病变区域可进行保守治疗，如果病变坏死面积大于5 cm2，应考虑胫骨截骨术和同时关节切开术移除软骨板并刮除软骨下的病灶[26]。LOTKE等[27]还进一步将病变面积分为小病变( < 3.5 cm2)、中等病变(3.5-5.0 cm2)和大病变( > 5 cm2)。AGLIETTI等[28]认为当坏死病灶面积大于5 cm2，保守治疗效果不佳。 LOTKE等[29]提出在正位X射线片上测算坏死区域的宽度占股骨髁的百分比以确定骨坏死病灶大小的方法，他们发现在累及32%的股骨内侧髁病变患者中，23个膝只有6个需要手术治疗，而超过50%股骨内侧髁坏死损伤的患者均需要人工关节置换术。AGLIETTI等[28]认为当坏死病灶宽度超过40%所累及的股骨髁时，保守治疗效果不佳。JURéUS等[30]使用LOTKE等[29]的测量方法对40例SONK患者研究发现当患者前后位X射线片病变坏死范围累及40%髁时，意味着存在骨关节炎，最终需行关节置换或截骨矫形术；提出病变范围很大(≥40%髁/前后位X射线片)或有早期骨关节炎的影像表现时，SONK保守治疗欠佳。SOUCACOS等[31]发现年龄< 65岁和病变小于股骨髁宽度50%的SONK患者行HTO治疗效果更好。此外，KERBOUL等[32]提出在正位和侧位X射线片上勾勒出骨坏死区的轮廓，并用测角仪测量坏死所涉及弧的角度，这两个角度加在一起就得到了合并坏死角，≤150°的区域归为小病变，151°-249°的区域归为中等病变，≥250°的区域归类为大病变。MONT等[24]将MUHEIM等[26]和LOTKE等[27]的方法进行了改良，在X射线片和磁共振图像冠状面上测量病变的宽度(A)和高度(C)，在矢状面上测量病变长度(B)，然后用A×B×C来近似计算病变体积，并分为小(0-10 cm3)、中(11-20 cm3)和大( > 20 cm3)。但这两种测量方法均未报道能预测SONK预后。 2.4 MR检查对病变区域的评估及对预后的影响 AKAMATSU等[18]对分别进行保守和手术治疗的两组SONK患者(n=27膝)随访1年，发现手术组的坏死区域MRI上深度(15.8-21.6 mm，平均18.7 mm)明显小于保守组的MRI上深度(21.8-26.5 mm，平均24.2 mm)，提出MRI上深度(矢状位坏死区域前后径，图3) > 20 mm预示该早期SONK患者保守治疗效果欠佳。"

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