关节镜下外侧支持带松解后的髌骨轨迹分析

doi:10.3969/j.issn.2095-4344.2014.51.025

摘要/Abstract

摘要：

背景：外侧支持带松解是治疗髌股关节紊乱症首选的治疗方法，然而有些文献报道部分病例的长期随访结果并不满意。

目的：分析关节镜下外侧支持带松解后的髌骨轨迹，以探讨外侧支持带松解后部分病例随访优良率下降的原因。

方法：临床采集符合纳入标准的57膝(34例)样本，松解前后分别行10°，20°，30°，40°屈膝位髌股关节CT扫描，测量髌股适合角、髌骨外移角和股骨远端内侧扭转角，比较松解前后髌骨轨迹的变化。

结果与结论：通过测量髌股适合角，髌骨外移角发现髌骨轨迹17膝松解后无改善，40膝明显改善。40膝的股骨远端内侧扭转角均大于9°，17膝的股骨远端内侧扭转角均小于9°。说明股骨远端内侧扭转角可能是影响外侧支持带松解后髌骨轨迹的一个重要因素。

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

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关键词: 组织构建, 肌肉肌腱韧带, 膝, 外侧松解, 髌骨, 髌股关节, 预后, 股骨, 力线

Abstract:

BACKGROUND: Lateral retinacular release is the preferred treatment for patellofemoral disorders, but the long-term follow-up results reported in some literatures are not satisfied.

OBJECTIVE: To analyze the improvement in patellar tracking after lateral patellar retinacular release and to determine the reasons for unsatisfactory outcomes during the follow-up.

METHODS: Fifty-seven consecutive knees (34 cases), which had undergone isolated lateral patellar retinacular release, were included in the study. CT scans of each knee were performed before and after surgery with the knee at different degrees of dynamic flexion: 10°, 20°, 30°, and 40°. The following parameters were evaluated: femoral distal medial torsion angle, patellar congruence angle, and patellar lateral translation angle. Preoperative and postoperative measures of patellar tracking were compared.

RESULTS AND CONCLUSION: There were 17 knees in which patellar tracking was not improved after surgery. Patellar tracking was improved in 40 knees after surgery. The improvement in patellar tracking did not reach the preoperative prediction when the femoral distal medial torsion angle was less than 9°. The femoral distal medial torsion angle is found to be an important factor influencing patellar maltracking recovery and may underlie unsatisfactory outcomes in some patients at a long-term follow-up.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

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Key words: biomechanics, ligaments, knee, patella

中图分类号:

R318

张建兵，郝建桥，申云龙，王合围，薛永安，刘斌. 关节镜下外侧支持带松解后的髌骨轨迹分析[J]. 中国组织工程研究, 2014, 18(51): 8330-8336.

Zhang Jian-bing, Hao Jian-qiao, Shen Yun-long, Wang He-wei, Xue Yong-an, Liu Bin. Analysis of patellar maltracking after arthroscopic lateral retinacular release[J]. Chinese Journal of Tissue Engineering Research, 2014, 18(51): 8330-8336.

图/表（结果） 3

Quantitative analysis of participants

Altogether, 43 cases met the inclusion, but 6 patients with external rotation of the femur were excluded. Three patients were lost to follow-up evaluation. At last, 34 patients (57 knees) were enrolled in the study. These 34 patients (57 knees) were located and the study was completed via follow-up.

The mean follow-up was (48.0±9.5) months (ranging 9-65 months), while the medical history range was from 1.0 to 5.5 years. Of the 57 knees (34 cases), 45 (78%) were from female patients and 12 (21%) from male patients.

Baseline comparison

Patellar maltracking unchanged group and patellar maltracking improved group were compared in baseline (Table 2).

Variation of patellar tracking after arthroscopic lateral retinacular release

According to previously published research^[8] and our experience, abnormal CA and PLTA values should be improved to nearly normal values (CA: -6°-6°, PLTA: 0°-5°) after LRR. Mean preoperative CA and PLTA values were (23.86±11.39)° and (43.59±10.88)° for 10° of knee flexion, (23.97±11.56)° and (43.70±11.67)° for 20° of knee flexion, (24.10±11.49)° and (43.73±11.53)° for 30° of knee flexion, and (23.51±11.91)° and (43.27±12.13)° for 40° of knee flexion, respectively. The overall mean preoperative FMTA was (10.14±6.45)°, which did not change markedly during the four knee flexion phases. Mean postoperative CA and PLTA values were (11.53± 9.12)° and (12.73± 10.63)° for 10° of knee flexion, (11.67±8.93)° and (12.85± 11.19)° for 20° of knee flexion, (11.97±9.31)° and (12.54± 10.19)° for 30° of knee flexion, and (10.97±8.45)° and (11.09±11.10)° for 40° of knee flexion, respectively. The mean postoperative FMTA was (10.14±6.45)°. Mean FMTA remained unchanged after LRR, regardless of the knee flexion phase. There were 17 knees in which patellar tracking (as indicated by CA and PLTA values) did not improve after surgery and 40 knees in which patellar tracking improved after surgery.

The quasi constant FMTA was further examined by comparison between the patellar maltracking unchanged group and patellar maltracking improved group using the Wilcoxon rank test (P > 0.05). Lysholm scores were not different between the two groups before and after LRR, nor were CA and PLTA values before LRR. After LRR, CA and PLTA values were significantly lower in the patellar maltracking changed group compared to the patellar maltracking unchanged group (P < 0.01; Table 1). As shown in Figure 2, FMTA influenced patellar-maltracking recovery after LRR. When FMTA was less than 9° or greater than 9°, postoperative CA and PLTA values were significantly different from preoperative values. Patellar tracking improvement did not meet preoperative expectations when the FMTA was less than 9°. Otherwise, we gathered from some patients that bilateral femoral distal ends presented a different extent of torsion, whose side of the larger FMTA had a better patellar tracking recovery than the lesser side (Figure 3). The evidence also substantiated the findings of the research.

参考文献

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引言

Arthroscopic lateral retinacular release (LRR) is the most effective technique for curing disorders of the patellofemoral joint. This technique has been used to treat a multitude of patellofemoral problems including instability, pain, and arthrosis^[1-5]. Described by Merchant and Mercer in 1974, lateral release is helpful for those who do not respond well to conservative therapy and whose symptoms and physical or radiographic findings do not require a more extensive patellar realignment procedure. Lateral release is also an option for adults with degenerative patellofemoral joints whose careers, athletic commitments, or personal lives force them to postpone total reconstructive knee surgery^[5]. Further, a large series of studies have demonstrated that LRR improves the rate of excellent to good patellofemoral joint outcomes^[2-4]. In contrast, findings from several other studies are inconsistent, showing that many patients having unsatisfactory outcomes at mid- to long-term follow-up after LRR^[6-7]. We have also observed this phenomenon of unsatisfactory outcomes at mid to long-term follow-up.

The mechanisms underlying unsatisfactory at outcomes mid to long-term follow-up after LRR are unclear. Several authors have stressed the relationship of preoperative diagnosis to the level of success after surgery. Better results are reported in those with lateral retinacular tightness and lateral patellar tilt with minimal subluxation and mild articular degeneration^[8-9]. Gecha and Torg stated that acceptable results can be expected in patients who have no evidence of patellar malalignment or hyperlaxity and who have tight lateral parapatellar soft tissue structures^[10]. Conversely, Handy and Miller in their review of patellar dislocation treatments noted that lateral retinaculum release is often an important part of restoring proper alignment^[11], and lateral retinacular release has been described as a treatment for recurrent patellar instability^[12]. Two studies have not found differences between patients with chondromalacia/osteoarthritis and those with subluxation/dislocation following lateral release^[13].

Improvement was reported in 95 of 102 knees in one 2-year follow-up study^[14]. There was a decrease in positive results between 1- to 2-year follow-up and 4-year follow-up studies^[15]. Follow-up from 2 to 9 years showed a 42% good or excellent rate. Similar results were found with follow-up from 1 to 8 years^[16-17]. Dandy et al examined patients 4 and 8 years after surgery and found that patellar stability improved^[18]. There was a decrease in excellent results from the 4- to 8-year period. Poor results were predicted in patients with hypermobility and dislocation. Recent studies have indicated that lateral release can make lateral subluxation morelikely or is not very effective for subluxators. Others stress the importance of the medial structures^[19-22]. These studies do not identify which patients had hyperlaxity as well as instability.

Eighty percent of patellofemoral pain cases can be relieved with physical therapy and quadriceps strengthening^[23]. Increasing quadriceps and hamstring strength by vigorous therapy has been shown to be directly proportional to postoperative success after lateral release, and postoperative radiographs after a lateral release do not show a resolution of tilt until after postoperative rehabilitation has begun.

Pathologic patellar alignment and tracking conditions that affect the patellofemoral joint start during the earliest portion of the range of motion of this joint, as the patella enters and moves within the femoral trochlear groove^[24]. With increasing increments of flexion, the patella is drawn deeper into the femoral trochlear groove and patellar displacement is less likely to occur^[21].

Current literature suggests the etiology of the disorders of petallofemoral joint is multi-factorial^[25], and closely related to static patellar malalignment and abnormal patellar tracking^[26-27]. While several factors are associated with patellofemoral pain, patellar maltracking is considered as an important contributor. Maltracking is typically characterized by excessive lateral alignment of the patella within the trochlear groove. Fewer studies have investigated the patellar tracking after the LRR. Hence, the purpose of this study was to investigate possible underlying mechanisms by examining preoperative and postoperative changes in patellar-tracking.

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材料方法

Design

A retrospective study.

Time and setting

The study was completed from May 2006 to December 2011 at the Department of Orthopaedics, Wenan Hospital, China.

Subjects

Patients who had undergone isolated LRR at Wenan Hospital from May 2006 to December 2012 were eligible for inclusion in this study. Attempts were made to contact all of the patients by messaging and phone. When a patient could not be contacted after three attempts, the patient was considered to be lost to follow-up. Patients were free to discontinue the study at any point. Patient characteristics are shown in Table 1.

The inclusion criteria were as follows: (1) a history of retro- or peri-patellar pain during physical activities including jumping, squatting, running, stair ambulation, or after prolonged sitting with flexed knees; (2) a history of nontraumatic knees, normal to nearly normal gait, good knee stability and normal alignment of lower extremities, knee flexion range from 90° to 135°, and a Q angle from 11° to 14°; (3) the presence of either pain or tenderness on palpation or compression of the patella or pain on patellar glide testing (sage sign); (4) malalignment of the patellofemoral joint; (5) an Insall-Salvati index ranging from 0.9 to 1.1 for males and 0.9-1.2 for females.

The study’s exclusion criteria were as follows: (1) any previous knee surgery; (2) a history of patellar dislocation; (3) isolated patellar tilt with subluxation; (4) metabolic or rheumatic diseases affecting the musculoskeletal system; (5) other systemic diseases that could affect the musculoskeletal system or sensorimotor performance; (6) femoral trochlear dysplasia, or medial or lateral compartment osteoarthritis; (7) positive findings on clinical examination of the knee ligaments, menisci, bursae, and tendons and tendon insertion points surrounding the knee.

All patients were known about the study before executing, and the subjects signed a consent form approved by the Administrative Regulations on Medical Institution^[28].

Methods

Dynamic CT scans of the patellofemoral joint

CT scans of each knee were performed before and after surgery with the knee at different degrees of dynamic flexion: 10°, 20°, 30°, and 40°. The following parameters were evaluated by examining CT images: femoral distal medial torsion angle (FMTA), patellar congruence angle (CA), and patellar lateral translation angle (PLTA; Figure 1). Lysholm scores were also determined.

All LRR procedures were performed by the same group of surgeons. In each case, the patella and trochlear cartilage showed degradation ranging from I to II type^[29]. All patients completed the same post-surgery rehabilitation program.

Data analysis

Knees were divided into two groups on the basis of whether patellar tracking remained patellar maltracking: unchanged group and patellar maltracking improved group.

Unchanged patellar tracking was indicated by a CA change of less than 12° and a PLTA change of less than 5° for at least three of the flexion positions assessed.

Main outcome measures

FMTA, CA, and PLTA were measured.

Statistical analysis

All statistical analyses were performed using SPSS 12.0 software (SPSS, Chicago, IL, USA). Preoperative and postoperative CA, PLTA, and FMTA values were compared by Student’s t-test and Wilcoxon rank test were used for comparison between patellar maltracking unchanged group and patellar maltracking improved group. Differences were considered statistically significant when P < 0.05.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

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讨论

In some patients after LRR, the good or excellent rate decreased in mid-long following-up, but no reports declared the reason. LRR can be successfully employed to cure disorders of patellofemoral joint. Many authors have reported that an excess of 80% of outcomes are excellent to good following LRR^[30-31]. Although this procedure has been readily accepted in clinical practice, we and others have found the rate of excellent to good outcome declines with increasing length of follow-up. Panni et al ^[32] reported that the average percent of satisfactory outcome in patients after more than 4 years of follow-up was only 63.5%, whereas 80% of the patients had satisfactory outcomes in the short-term (< 4 years). Other researchers have reported decreases in the percent of positive outcomes between 1 to 2 years follow-up and 4 years follow-up^[33]. Follow-up from 2-9 years has been reported to be associated with a 42% good to excellent rate, while similar results have been reported after 1-8 years of follow-up. The reason for this decrease in positive outcomes with increasing duration of follow-up is unclear; hence, we performed this study to examine changes in patellar tracking after LRR.

As we all known, patellar maltracking is the reason that leads to patellofemoral joint problems. Numerous studies have reported on patellar tracking in cases with suffering from the patellofemoral joint disorders^[34-35]. Few studies have applied patellar tracking investigation in the patients after surgery. So we try to find factors affecting the patellar tracking in patients after LRR. Knee flexed range of 0°-40°, the most unstable patella in this range, was taken as assessing extent; the daily motive range of knee spanned 0°-40°. The tracking pattern of the knee may be different when the knee is flexed from an extended position to when it is extended from a fixed position. In this study we performed evaluations during the phase of flexion because of the onset of symptoms during knee flexion.

It is not important factor that patellar maltracking still improved after LRR in the unsatisfied patients. Patellar malalignment may cause an aberrant dispersion of the patellofemoral joint reaction force and thus cause pain and/or structural progression. LRR relieves the symptoms of excessive lateral pressure. It has now been recognized that this condition is an acceptable indication for isolated LRR, which yields reproducible and predictably good results. However, as previously noted, in our experience, the rates of satisfactory outcome tend to decline at mid to long-term follow-up. We surmised that a lack of improvement in patellar tracking after LRR may underlie this decrease in satisfactory outcome. Indeed, patellar maltracking has been shown to be correlated with patellofemoral joint dysfunction^[36]. Therefore, patellar maltracking may lead to recurrent incipient symptoms in the patellofemoral joint at mid- to long-term follow-up. We studied many former patients to determine the relationship between the FMTA and alignment improvement after LRR. Femoral distal medial torsion affects alignment of the patella and stresses within the patellofemoral joint. Lee et al ^[37] showed that fixed femoral rotation of the femur can lead to nonlinear increases in patellofemoral contact pressures, with small increases in pressure with 0°-20°? of internal rotation and much greater increases in pressure with 20°-30° of internal rotation. Besier et al^[38]performed a modeling study examining the influence of internal and external femoral rotation on cartilage stresses within the patellofemoral joint and concluded that hydrostatic pressure and octahedral shear stresses within the cartilage of the patella and femur increase with internal rotation of the femur. An important finding from our study is that patellar maltracking improvement is not apparent when the FMTA is less than 9°. Nevertheless, the knees with patellar maltracking, the FMTA larger than 9°, has improved more satisfactorily than the knees of the FMTA lesser than 9°. The mechanism underlying this lack of improvement might stem from increasing the lateral part of the trochlear groove due to femoral distal medial torsion preventing patellar lateral translation. In contrast, normal patellar tracking is easily recovered with a synergistic reaction of the medial retinacular. Our findings suggest that the resistance of lateral translation is lost after LRR in patients with lower FMTA values. Furthermore, the ability to prevent patellar lateral translation of lateral component of trochlear groove decreased in comparison to preoperation. Christoforakis and colleagues have reported that patellar lateral subluxation is more likely to occur following LRR. We therefore demonstrated above reason leading to these results. The results of this research are important for an accurate prognostic assessment of the disorders of patellofemoral joint. This study has several limitations that must be acknowledged. Firstly, many factors are known to influence alignment of patellofemoral joint^[39]. Although we controlled for factors known to decrease bias, we were not able to control for all factors known to influence alignment of patellofemoral joint. Another issue that may affect our findings is the level of cartilage degeneration. Little is known about the effect of cartilage degeneration in this regard; hence we used inclusion criteria of I to III type^[29]. The area of cartilage degeneration is difficult to calculate arthroscopically. We found that only six patients had external rotational of the femur. The effect of external rotation of the femur may impact patellofemoral joint and this needs to be taken as a new research, we did not investigate in this study because the femur, external or internal rotational, impacted differently on the patellofemoral joint.

Lateral retinacular release performed in isolation for patellofemoral disorders remains controversial^[40]. A lack of well-designed studies with clearly defined inclusion, standardized methods of assessment and adequate follow-up hinders an informed opinion about the effectiveness of this procedure. It is important to appreciate what will be achieved by release of the lateral retinaculum. For example, in patellar instability it is unrealistic to expect a release of the lateral retinaculum to correct patellar maltracking and instability if there is also trochlear dysplasia, deficiency of the medial patellofemoral ligament, abnormal limb alignment or tibial torsion^[41]. Generally, none of those studies has reported the femoral torsion affected, and our study is the first to demonstrate which potentially affects the outcomes of LRR.

In this study, we have described our findings regarding the impact of FMTA on the prognosis of the patellofemoral joint after LRR. Our findings suggest that the FMTA may affect prognosis. Although further larger scale studies are needed to confirm our findings, we suggest that assessment of the FMTA may allow clinicians to determine which patients may benefit most from LRR and which patients may benefit from alternative treatment approaches.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

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