Computerized tomography of the patellofemoral joint before and after lateral release or realignment

Computerized tomography (CT) provides an accurate diagnostic tool for evaluating tilt and subluxation of the patella. Using a previously described technique, this study reviews 62 computerized tomograms, including those of 21 patients before and after lateral release or anteromedial tibial tubercle transfer. One patient was evaluated before and after soft-tissue realignment of the patella. Additional CT studies were evaluated to establish the most appropriate reference line for determining patellar tilt. Results show that lateral retinacular release effectively reduces abnormal patellar tilting as determined by CT. Anteromedial tibial tubercle transfer similarly reduces abnormal tilt. Patellar subluxation may improve substantially following either lateral release or anteromedial tibial tubercle transfer, but this study suggests that correction of subluxation is less consistent than reduction of abnormal tilt with tibial tubercle transfer or lateral release alone. Once articular degeneration has progressed to the point of facet collapse, lateral release fails to restore normal tilt.     

Evaluation of patients with persistent symptoms after lateral retinacular release by kinematic magnetic resonance imaging of the patellofemoral joint

The arthroscopic lateral retinacular release is typically performed to treat patellar pain and instability. This procedure was previously considered to be relatively benign with a low associated complication rate. However, a high incidence of medial subluxation of the patella was recently reported in patients with persistent symptoms after lateral retinacular release. Because the use of physical examination criteria may not always be sufficient to assess patellar alignment, 40 patients (43 knees) were evaluated by the newly developed technique of kinematic magnetic resonance imaging of the patellofemoral joint. One (2%) patellofemoral joint had normal patellar alignment, 10 (23%) had lateral subluxation of the patella, 1 (2%) had excessive lateral pressure syndrome, 27 (63%) had medial subluxation of the patella, and 4 (9%) had lateral-to-medial subluxation of the patella. Seventeen of 40 patients (43%) with unilateral arthroscopic lateral retinacular releases had medially subluxated patellae on the unoperated joints. Because patellar malalignment commonly affects bilateral joints, medial subluxation of the patella may have been present before the lateral retinacular release but was not recognized in these patients.     

Treatment of chondromalacia patellae by lateral retinacular release of the patella

A series of 59 knees in 58 patients were surgically treated from 1977 to 1982 for chondromalacia patellae, and were followed for an average of 1.2 to 4.6 years after the operation. The operative procedure was open lateral retinacular release in all knees. In knees with recurrent patellar subluxation, the number of poor results increased from 24% to 70%, and in knees with no subluxation from 21% to 24%. The difference after 4.6 years was statistically significant. No correlation between the severity or location of the cartilage changes and the operative effect was found. Open lateral retinacular release is an acceptable treatment of chondromalacia patellae without subluxation of the patella, whereas in the presence of recurrent subluxation, the release does not correct the basic biomechanical disturbance.     

Patellofemoral Pain Disorders: Evaluation and Management

Patellofemoral pain disorders can be difficult to diagnose. Careful attention to the history and physical examination is central to accurate diagnosis. Standardized office radiographs are sufficient in most cases. Computed tomography of the patellofemoral joint (precise midpatellar transverse images through the posterior femoral condyles with the knee at 15, 30, and 45 degrees of knee flexion) will provide valuable objective information regarding subtle abnormalities of patellar alignment. Magnetic resonance imaging and radionuclide scanning may be helpful in selected cases. By differentiating between rotational (tilt) and translational (subluxation) components of patellar malalignment, the clinician will be better able to prescribe appropriate treatment. It is also extremely important to localize and quantitate articular and retinacular abnormalities. While nonoperative treatment is usually successful, surgery is sometimes required. Lateral release will relieve tilt and associated pain in the lateral retinaculum. Realignment of the extensor mechanism, usually at the level of the tibial tubercle, is necessary to control lateral tracking (subluxation) of the patella. If there is lateral or distal medial articular damage related to chronic lateral tilt and/or subluxation, shift of the tibial tubercle will help to unload damaged cartilage while realigning the extensor mechanism.     

Long-term functional outcome after lateral patellar retinacular release in adolescents: an observational cohort study with minimum 5-year follow-up

BACKGROUND: Lateral patellar retinacular release has been recommended for patients with patellar tilt, tight lateral retinaculum, patellar subluxation, patellar dislocation, and patellofemoral pain. Studies of long-term outcomes after lateral release are limited, especially for differing indications. HYPOTHESIS: Adolescents do well after lateral retinacular release in the 5- to 22-year time frame. METHODS: Patients having undergone lateral retinacular release between the years of 1981 and 1999 were contacted. Evaluation was by the Cincinnati and Lysholm scales and by level of satisfaction and need for reoperation. RESULTS: One hundred forty knees were studied. Mean age at operation was 15.4 years (SD, 2.7 years). Average follow-up was 8.5 (SD, 4.1 years; range, 5.2-22.5 years). Twenty-five patients had needed reoperation, indicating failure of the index operation. Kaplan-Meier survivorship was 78% at 15 years. Cincinnati and Lysholm scores indicated well-functioning knees in those not requiring reoperation. Overall satisfaction improved as time from operation increased.Comparisons were made between the group requiring reoperation and those who did not. Focus was placed on knees with patellar maltracking or tilt versus patellar instability and between males and females. No differences were found among groups for reoperation rate, level of satisfaction, average Lysholm score, or average Cincinnati score. There were no differences in demographics or outcome measures between patients with patellar instability and those with tilt. Instability patients trended toward higher reoperation rates than did tilt patients, but the difference was not significant. There were no differences between males and females. CONCLUSION: The majority of patients are satisfied with their knee 5 to 22 years after lateral patellar retinacular release and scored well on questions rating knee health and function.     

股四头肌对髌股关节影响的临床和实验观察

目的　从临床和实验二个方面研究股四头肌对髌股关节运动的影响。方法　对一组 2 6例 5 2膝患者进行动力性CT检查 ,了解股四头肌收缩状态对髌股关节排列的影响 ;对一组标本进行生物力学实验 ,用压敏片技术直观地测得股四头肌肌力变化对髌股关节接触压力的影响。结果　静力性CT检查发现有 12膝髌骨半脱位和 14膝髌骨外倾 ,其余病例动力性CT检查又发现有 2 1膝在股四头肌收缩状态下髌骨半脱位 ,9膝髌骨外倾。力学实验中发现随股内侧肌肌力下降髌股接触面趋向外侧。结论　股四头肌各肌组的肌力不平衡对髌股关节的接触压力及髌骨位置有较大的影响 ,临床上应重视对股四头肌肌力的恢复。     

Lateral retinacular release of the patella

From October 1977 through January 1984, 2,330 arthroscopic procedures of the knee were performed by one of the authors (G.J.S.). Among these procedures, 35 lateral retinacular releases were performed through minimal, lateral incisions. Twenty-two knees in 22 patients were available for follow-up evaluation, and these cases were reviewed retrospectively. The average age of the patients at the time of surgery was 22.6 years. The average follow-up period was 48 months. The patients were divided into three subgroups on the basis of their preoperative diagnosis. Group I (eight knees) had a history of patellar dislocations; group II (seven knees) had recurrent patellar subluxation, identified by history and physical and radiographic examinations; and group III (seven knees) had patellar pain without a history of dislocations or subluxation and with no symptoms of instability. All of these patients underwent diagnostic arthroscopy and lateral retinacular release, as well as arthroscopic treatment of associated pathology. Postoperatively and at the time of followup, all patients were evaluated for pain, function and patellar instability. In 15 patients with a history of patellar dislocation or subluxation, 67% were found to have had significant improvement in their symptoms, which was borne out by the findings during physical examination. None was worse following treatment. Among the seven patients with no history of patellar dislocation or subluxation, only one of the seven had a satisfactory result. Based upon the findings of this study, it was concluded that arthroscopic lateral retinacular release is a reasonable, initial step in the surgical treatment of patellar dislocation or subluxation, resistant to conservative treatment. Its efficacy in cases of recalcitrant patellar pain without a history of instability is doubtful.     

Patellar retinacular peel: an alternative to lateral retinacular release in total knee arthroplasty

The need to perform a lateral retinacular release (LRR) during total knee arthroplasty (TKA) may be lessened or eliminated by performing a patellar retinacular peel (PRP). PRP involves peeling the extensor retinaculum off the dorsolateral border of the patella to the extent necessary to facilitate patellar eversion. Generally, a portion of the lateral patellar facet is removed to allow conformity with a round patellar prosthesis. The combination of retinacular peel and partial facetectomy decreases lateral retinacular tension, which reduces the tendency toward lateral subluxation. In the study reported here, a series of 50 TKAs that included a PRP in all cases was compared with an earlier series of 50 TKAs that included LRR for control of patellar tracking, as needed. The incidence of anterior knee pain was lower in the PRP group than in the LRR group, though this difference was not significant from a statistical perspective. The 2 groups were virtually identical on other comparison criteria. PRP seems to be a viable alternative to LRR.     

Indications for lateral retinacular release in total knee replacement

The rule of no thumb test was compared with the towel clip test in determining the need for lateral retinacular release in 200 consecutive primary total knee replacements. The towel clip test was positive in 13 knees (6.5%) and the rule of no thumb test was positive in 78 knees (39%). Using a positive towel clip test as the indication for lateral retinacular release, there was no radiographic evidence of patellar tilt, subluxation, or dislocation in any knee at 6 months postoperatively. Therefore, the rule of no thumb test falsely predicted the need for lateral release in 65 knees (32.5%). The authors advocate the towel clip test to determine the need for lateral retinacular release.     

关节镜下外侧支持带松解治疗髌骨外侧高压综合征

目的探讨关节镜下外侧支持带松解治疗髌骨外侧高压综合征的效果和临床意义.方法采用关节镜下外侧支持带松解术治疗39例(51膝)髌骨外侧高压综合征.男1例(1膝),女38例(50膝);单膝27例,双膝12例;平均年龄49.6岁(28～71岁).临床症状以髌股关节钝痛为特点,疼痛位置不易确定,髌股关节负荷过度的活动会使疼痛加重.物理检查见Q角增大(＞20°)45膝,髌软骨外侧小面抠触痛50膝,外侧支持带压痛39膝,被动髌骨倾斜试验阳性51膝,内外侧滑动试验阳性49膝,压髌试验阳性51膝.X线检查轴位片见髌股对合角异常32膝.术中在关节镜监视下,用射频汽化钩刀松解外侧支持带,必要时可向近端扩大松解范围,切断部分股外侧肌,达到完全松解.结果术后所有病例均得到随访,平均随访14.5个月(3～26个月).疗效评定参照改良Lysholm评分标准,优37膝,良12膝,可2膝.Lysholm评分从术前平均(62.04±5.98)分(49～75分)提高到术后平均(93.71±3.55)分(86～100分),有显著性差异(t=6.63,P＜0.001).髌股对合角异常的32膝中术后有30膝髌股对合角恢复正常(94%).术后5膝有血肿形成(10%).结论关节镜下外侧支持带松解是一种微创的软组织平衡手术,能够有效地缓解髌骨外侧高压综合征引起的髌股关节疼痛,且并发症较少.     

Scintigraphic determination of patellar viability after excision of infrapatellar fat pad and/or lateral retinacular release in total knee arthroplasty

A prospective study ascertained the effect of lateral retinacular release and/or excision of the infrapatellar fat pad on patellar vascularity after total knee arthroplasty. Fifty patients (70 knees) had postoperative technetium bone scans, which revealed a higher incidence of vascular compromise of the patella after lateral release than without lateral release. Excision of the infrapatellar fat pad, commonly performed to enhance exposure and simplify access to the proximal tibia, did not compromise patellar vascularity.     

Lateral release rates after total knee arthroplasty.

For a total knee replacement to function well, the patella must track centrally in the trochlear groove. A lateral release may be required to ensure such central tracking. During surgery, an evaluation was made of patellar tracking in 178 patients undergoing total knee replacement. The Genesis II prosthesis with a deep-dish tibial insert was used for all the patients. The evaluation was made using the nontouch technique and the axial traction (modified no-touch) technique before and after release of the tourniquet. With the tourniquet still inflated, there were 29 knees in which the patella tilted laterally and 11 additional knees in which the patella subluxed laterally. Using the modified no-touch technique, there were only 12 knees in which the patella tilted laterally and five in which it subluxed laterally. With the tourniquet deflated, only nine of the patellas tilted laterally and three subluxed laterally. It was only in this final group that a lateral release was done for an overall lateral release rate of 6%. Eleven of these 12 knees had a preoperative fixed valgus deformity greater than 10 degrees. Only one lateral release was required for a patient with a preoperative varus deformity. Four patients with a preoperative fixed valgus deformity and a laterally subluxed patella did not require a lateral release. Axial realignment and reconstitution of an anterior trochlear surface by the implant were sufficient to centralize the patella. Had only the no-touch test been used, there would have been 18 unnecessary lateral releases done. When the knees were evaluated radiographically, there was no statistical difference in patellar position between that group and the knees that required a lateral release. Overall in the entire group at 6 weeks after surgery, 105 knees (59%) had no patellar tilt. At 3 months, as quadriceps tone returned to normal, 138 knees (79%) had no patellar tilt. Thirty-three of the remaining 35 knees had a patellar tilt less than 10 degrees. None of the patients had lateral patellar subluxation at any time after surgery.     

Anatomy of the knee extensor mechanism: correlation with patellofemoral arthrosis

The patellofemoral articulation is a common and significant source of disability and discomfort in the aging population. This study examined the anatomy of the knee extensor mechanism in patients having primary total knee arthroplasties, characterized the anatomic variations of the extensor mechanism, and correlated these findings with the location and extent of osteoarthritic change of the patellar undersurface. Sixty-two knees (57 patients) were evaluated prospectively. Specific characteristics that were analyzed included the mean Outerbridge grade for rating patellar cartilage degeneration and anatomic patterns of the extensor mechanism. Knees with a quadriceps tendon width at 2 and 5 cm above the patella that differed by less than 1 cm had more statistically significant patellar degeneration in all patellar locations than knees with tendon width differences greater than 1 cm. Anatomic variations, such as tendons with minimal increments in width in the proximal-distal direction, may be associated with an increasing amount of patellar arthrosis at the lateral facet, central ridge, and, most significantly, medial facet.     

Subvastus and medial parapatellar approaches in total knee arthroplasty

This retrospective study compared the outcome of two consecutive groups of patients having primary total knee arthroplasty. The arthroplasties were performed in the first group (169 arthroplasties in 143 patients) from 1988 to 1992 using a medial parapatellar approach, and in the second group (167 arthroplasties in 148 patients) from 1992 to 1996 using a subvastus approach. The patient outcomes were evaluated at 6 months, and were based on clinical and radiographic measures, occurrence of intraoperative lateral retinacular release, and incidence of postoperative patellar subluxation. There were no significant differences between the two groups for range of motion, Knee Society knee and function scores, and stair climbing ability. The patella tracked centrally in significantly more knees with the subvastus approach (139 of 167 knees, 83%) than with the parapatellar approach (107 of 169 knees, 63%). There were significantly fewer knees in the subvastus group requiring a lateral retinacular release (62 of 167 knees, 37%), compared with the parapatellar group (113 of 169 knees, 67%). The authors concluded that the subvastus approach led to improved patellar tracking and stability. Although the surgical and rehabilitative protocols were identical for both groups, the results may have been affected by changing circumstances during the 9-year period of the study.     

Evaluation of patellar retinacular tension during total knee arthroplasty: Special emphasis on lateral retinacular release

Tension of a suture placed to the patella to close the medial capsule during 35 primary total knee arthroplasties was measured. The increase in tension with flexion after arthrotomy was significantly smaller in 10 knees with a subvastus incision (subvastus group) than in 25 knees with a standard medial parapatellar incision (standard group). With the prosthesis in place, the patella showed maltracking with the no-thumb technique in 1 knee (10%) of the subvastus group and in 9 knees (36%) of the standard group. A lateral retinacular release was performed in 5 of these 10 knees but not in the remaining 5 knees because the increase in tension was a minimum. There was no case of patellar maltracking at an average follow-up period of 2.1 years after surgery, suggesting that a lateral release is not always needed if retinacular tension shows no significant increase, even cases where the patella dislocates with the no-thumb technique.     

髌股关节排列异常的CT检查

对髌股关节进行ＣＴ测量,确定有无髌股排列异常。方法 对一组２０例４０侧膝关节进行ＣＴ检查,分别在股四头股收缩和松驰状况下扫描,对ＣＴ图像进行测量。结果４０膝中有１０膝为静力性骨外侧半脱位,另３０膝中有１６膝为动力性髌骨半脱位;４０膝中１１膝为性髌骨外倾,另有７膝为动力性髌骨外倾。     

Rotating platform knees did not improve patellar tracking: a prospective, randomized study of 240 primary total knee arthroplasties

Renewed interest in mobile-bearing total knee replacement designs has been generated by the concept of self alignment and the suggestion that those designs can accommodate small mismatches in the rotational position of the tibial and femoral components. Self alignment might improve patellar tracking, decrease the prevalence of lateral retinacular release and postoperative patellar tilt or subluxation, improve knee flexion, and improve patellofemoral function during daily activities such as stair climbing. This prospective randomized study of 240 patients used a single posterior-stabilized femoral component and included three groups of 80 patients: an all-polyethylene group, a modular metal-backed group, and a rotating platform tibia group. The prevalence of lateral retinacular release was 3.8% in each group. The prevalence of patellar tilt was 5% (all-polyethylene group), 7% (modular metal-backed group), and 11% (rotating platform group). Preoperative motion was not significantly different and both the 3-month flexion (112 degrees , 110 degrees , and 108 degrees ) and 1-year flexion (116 degrees , 117 degrees , and 115 degrees ) were not significantly different among the all-polyethylene, modular metal-backed, and rotating platform groups, respectively. Preoperative stair climbing scores were not significantly different and both the 3-month (38, 41, and 35 points) and 1-year (44, 46, and 42 points) scores were not significantly different. In this prospective randomized study, the rotating platform knee design did not decrease the prevalence of lateral retinacular release or patellar tilt or subluxation and did not increase knee flexion or improve stair climbing ability at 3 months or at 1 year postoperatively when compared with a posterior-stabilized, fixed-bearing knee.     

Assessment of Patellar Morphology in Trochlear Dysplasia on Computed Tomography Scans

ObjectiveTo evaluate the patellar morphology of trochlear dysplasia and normal knees in different genders and in different severities of trochlear dysplasia on CT scans.MethodsA total of 75 patients with trochlear dysplasia (110 knees) treated at the Third Hospital of Hebei Medical University from December 2013 to December 2018 were included in an experimental group, and an age‐matched and sex‐matched cohort of 46 patients with normal trochlear shape (61 knees) were randomly selected into a control group. The experimental group was divided into a female experimental group (Group FE, 47 patients, 72 knees) and a male experimental group (Group ME, 28 patients, 38 knees); the control group was divided into a female control group (Group FC, 31 knees, 24 female patients) and a male control group (Group MC, 30 knees, 22 male patients). Furthermore, according to the severity of trochlear dysplasia, Group FE was divided into a female low‐grade dysplasia group (Group FL, 20 knees) and a female high‐grade dysplasia group (Group FH, 52 knees); Group ME was divided into a male low‐grade dysplasia group (Group ML, 16 knees) and a male high‐grade dysplasia group (Group MH, 22 knees). All participants had undergone CT scans in the supine position; the patellar width and thickness, the lateral patellar facet angle, the Wiberg angle, and the Wiberg index were measured and compared.ResultsIn trochlear dysplasia knees, the mean patellar width and thickness and the lateral patellar facet angle were significantly smaller; the mean Wiberg index was significantly larger than in normal knees, regardless of gender (P < 0.05); and there was no statistically significant difference in the mean Wiberg angle (P > 0.05). In the female groups, the mean patellar width and thickness and the Wiberg angle were significantly smaller; the mean lateral patellar facet angle was significantly larger than those in the male groups (P < 0.05); and there was no significant difference in the mean Wiberg index (P > 0.05). In the low‐grade dysplasia group, the mean Wiberg index was smaller than that in the high‐grade dysplasia group (P < 0.05), regardless of gender; however, there was no significant difference in the mean patellar width and thickness, the lateral patellar facet angle, and the Wiberg angle in low‐grade and high‐grade dysplasia (P > 0.05).ConclusionOn CT scans, the patella in trochlear dysplasia had a smaller width, a thinner thickness, a lengthened lateral facet, and a more flattened articular facet. In addition, the patellar articular facet was more prominent in female patients. With the severity of trochlear dysplasia increased, the lateral patellar facet became longer. In addition, the abnormal stress distribution on the patella influenced the patellar morphology in trochlear dysaplasia.     

髌骨半脱位70例治疗分析

目的探讨髌骨半脱位的治疗方法及其预后。方法回顾性分析70例（130膝）髌骨半脱位患者的临床资料,其中男30例,女40例;年龄10～48岁,平均23岁。患者髌骨的形态均为WibergⅡ、Ⅲ型,其中伴有外侧髌股关节骨关节炎者58例108膝,高位髌骨23例46膝,外伤后股四头肌内侧头肌张力不良10例10膝。Q角20°～40°。全部行手术治疗,手术方式包括：髌外侧支持带充分松解（130膝）;髌内侧支持带紧缩、股内侧肌移位至髌骨前内侧（12膝）;髌骨外侧部分切除（17膝）;胫骨结节前、内侧移位（46膝）,平均内移1．0cm、前移1．2cm;缝匠肌前移（11膝）,半腱肌前移（13膝）;关节镜下髌外侧支持带松解,髌内侧支持带紧缩（31膝）。术中见全部病例髌外侧支持带均明显增厚。结果随访3～180个月,根据Insall等评分系统评估分析疗效,术后疗效优78膝,良33膝,可12膝,差7膝。患者术后疼痛、关节活动功能均得到明显改善,尤其是解除膝前痛效果显著。结论根据病因及病理改变选择恰当的手术方式治疗髌骨半脱位均可取得满意的效果,特别是关节镜手术具有创伤小、恢复快的特点,值得进一步推广应用。     

Factors affecting patellar tracking after total knee arthroplasty

This study examined factors that influence patellar tracking after total knee arthroplasty. A total of 62 knees were evaluated radiographically for postoperative patellar tracking. Six factors were examined regarding their influence on postoperative patellar tracking. This study showed the effects of patellar component position, patellar resection angle, and lateral retinacular release on postoperative patellar tracking. There was no significant effect of the remaining 3 factors: the thickness of the patellar resection, preoperative patellar tilt, and rotational alignment of the femoral component. A medialized patellar component and obliquity of resection of the patella are effective for obtaining proper patellar tracking, whereas the evaluation of the influence of the external rotation of the femoral component requires more clinical studies.