Predicting the Probability of Recurrence Based on Individualized Risk Factors After Primary Lateral Patellar Dislocation Treated Nonoperatively

PURPOSE

To develop a comprehensive and effective personalized scoring system on the basis of demographic and clinical characteristics for predicting recurrence probability in patients with primary lateral patellar dislocation (LPD).

METHODS

Participants included 261 primary patients with LPD with 2-year minimum follow-up from our hospital across 2013 to 2020. Demographic and clinical characteristics were collected retrospectively. The backward stepwise method was performed to identify independent predictors and construct a nomogram to predict the probability of recurrence. The predictive performance was assessed by receiver operating characteristic curves, calibration plots, and decision curve analysis.

RESULTS

After variables selection, 6 independent predictors of recurrence (skeletal maturity, trochlear dysplasia, tibial tuberosity-trochlear groove distance, mechanical axis deviation, Insall-Salvati index, and patellar tilt) were enrolled in our model. Validation of this nomogram in both training and validation cohort revealed powerful predictive ability, with an area under the curve of 0.962 and 0.977, respectively. The nomogram also showed great calibration and good clinical practicability.

CONCLUSIONS

Our study presented a nomogram that incorporates 6 independent risk factors (skeletal maturity, trochlear dysplasia, tibial tuberosity-trochlear groove distance, mechanical axis deviation, Insall-Salvati index, and patellar tilt), which can be conveniently used to accurately predicts the risk of recurrence after primary LPD in individual cases.

LEVEL OF EVIDENCE

Level III, retrospective comparative prognostic study.

Diagnosis and treatment of recurrent patellar dislocation with knee extensor device combined with rearrangement

OBJECTIVE

This study aimed to investigate the clinical effects of combining knee extension mechanism (EM) with rearrangement in the treatment of recurrent patellar dislocation (RPD).

PATIENTS AND METHODS

Eighty-four patients with RPD admitted to the First Affiliated Hospital of Kunming Medical University were included. In this work, all patients received routine computed tomography (CT) examinations. In addition, the evaluation factors of EM combined with rearrangement therapy in RPD patients were analyzed using logistic regression.

RESULTS

Lysholm and Kujula scores, femoral canal width, patellar canal width, patellar tilt angle (PTA), and lateral patellar displacement (LPD) were significantly increased at 1 and 3 years after treatment (p < 0.05). LPA was significantly decreased, while the tibial tuberosity trochlear groove of the femur (TT-TG) demonstrated no considerable differences (p > 0.05). The good rate of the short-term Insall-Salvati index was 78.6%, and that of the long-term Insall-Salvati index was 76.1%. The combination of the knee extension device and rearrangement therapy has a higher rate of short-term and long-term Insall-Salvati index (ISI) excellence. In addition, the range of motion of the knee joint increased significantly, and the Q Angle decreased significantly (p < 0.05). Logistic regression analysis showed that age and ISI were highly correlated with the evaluation of therapeutic effects in patients with RPD.

CONCLUSIONS

EM combined with rearrangement in the treatment of RPD had positive short-term and long-term efficacy, high application value, and age, which can be popularized in clinical applications and have positive diagnostic value.

Patellar instability: will my patella dislocate again?

PURPOSE OF REVIEW

The incidence of patellar instability in pediatric patients ranges is 50-100 in 100,000 patients per year. Risk of recurrent dislocations however has been cited from 8.6% to 88% depending on individual patient factors. This manuscript highlights the demographical, historical, and anatomic factors associated with recurrent patellar instability following a first-time patella dislocation in the pediatric population.

RECENT FINDINGS

In recent years, various studies have focused on identifying risk factors for recurrent patellar instability following a primary patellar dislocation. A mix of patient factors, including age of first dislocation, patella alta, elevated tibial tubercle to trochlear groove and trochlear dysplasia have all been noted in the literature, which have helped to develop various scoring tools to predict recurrent dislocation following nonoperative treatment.

SUMMARY

Risk of recurrent patellar instability in patients who have previously suffered a patellar dislocation can be due to many factors. These risk factors should be used and applied to a variety of risk scores in order to provide physicians and healthcare providers with a tool to counsel patients and families on their patellar redislocation risk and help guide further management.

Surgical versus nonsurgical treatment of primary acute patellar dislocation: A systematic review and meta-analysis

BACKGROUND

To systematically review the efficacy of surgical versus nonsurgical treatment for acute patellar dislocation.

MATERIALS AND METHODS

PubMed, Cochrane, and Embase were searched up to February 12, 2019. After removing duplicates, preliminary screening, and reading the full texts, we finally selected 16 articles, including 11 randomized controlled trials and 5 cohort studies. The quality of the enrolled studies was evaluated by Jadad score or Newcastle-Ottawa scale. Meta-analyses were performed using odds ratio (OR) and standardized mean difference (SMD) as effect variables. The clinical parameters assessed included mean Kujala score, rate of redislocation, incidence of patellar subluxation, patient satisfaction, and visual analog scale (VAS) for pain. Evidence levels were determined using GRADE profile.

RESULTS

The 16 included studies involved 918 cases, 418 in the surgical group and 500 in the nonsurgical group. The results of the meta-analysis showed higher mean Kujala score (SMD = 0.79, 95% confidence interval [CI] [0.3, 1.28], P = .002) and lower rate of redislocation (OR = 0.44, 95% CI [0.3, 0.63], P < .00001) in the surgical group than the nonsurgical group, but showed insignificant differences in the incidence of patellar subluxation (OR = 0.61, 95% CI [0.36, 1.03], P = .06), satisfaction of patients (OR = 1.44, 95% CI [0.64, 3.25], P = .38), and VAS (SMD = 0.84, 95% CI [-0.36, 9.03], P = .84).

CONCLUSION

For patients with primary acute patellar dislocation, surgical treatment produces a higher mean Kujala score and a lower rate of redislocation than nonsurgical treatment.

Evaluation of the utility of teaching joint relocations using cadaveric specimens

BACKGROUND

Like other procedural skills, the ability to relocate a joint is an important aspect of junior doctor education. Changes in the approach to teaching and learning from the traditional apprenticeship-style model have made the teaching of practical skills more difficult logistically. Workshops utilising cadaveric specimens offer a solution to this problem.

METHODS

One hundred forty-six fourth year medical students were randomly divided into 5 groups. Each group received a different teaching intervention based on ankle, patella and hip relocation. The interventions consisted of online learning modules, instructional cards and workshops using skeleton models and cadaveric dislocation models. Following the intervention students were given a test containing multiple choice and true/false style questions. A 13-item 5-point Likert scale questionnaire was also delivered before and after the intervention. The data was analysed using one-way analysis of variance (ANOVA) and the Bonferroni post-hoc test.

RESULTS

Compared to the instructional cards group, the other 4 groups showed a 10.8-19.2% improvement in total test score (p < 0.01) and an 18.4-25.3% improvement in self-reported understanding and confidence in performing joint relocations (P < 0.01). There was no significant difference in total test scores between groups exposed to cadaveric instruction on the relocation of one-, two- or all three- joints, nor any significant difference between all the cadaveric dislocation groups and the group receiving instruction on the skeleton model.

CONCLUSION

The results of the present study suggest that workshops utilising cadaveric dislocation models are effective in teaching joint relocation. In addition, the finding that lower fidelity models may be of equal utility may provide institutions with flexibility of delivery needed to meet financial and resource constraints.

[Patellar instability : diagnosis and treatment]

The aim of this paper is to present recent advances in surgical management of patellar instability. Several anatomical factors were reported to promote instability. We propose to classify them in two groups. Extra articular factors are valgus and torsion deformity. Articular factors include trochlea and patella dysplasia, tibial tubercle lateralization and medial patellofemoral ligament (MPFL) insufficiency. Acute patellar dislocations are treated conservatively, with exception for osteochondral and MPFL avulsion fractures that require acute reinsertion. Surgery is considered for recurrent instability. As we aim for a correction of all contributing elements, we prefer a two stages approach. Extra articular factors are treated first by osteotomy, followed by articular factors after 4-6 months. This allows separate rehabilitation protocols.

[Treatment of patellar instability]

First-time patellar luxation appears typically in teenagers and young adults below the age of 16 years, with a prevalence of 45/100,000/year. This luxation is treated with brief limited mobility in a bandage, and with a complementary physiotherapy if the mobility is influenced afterwards. Risk factors for patellar instability are patellofemoral dysplasia, hyperlaxity, patella alta and valgus malalignment in the knee joint. In case of repeated luxation the treatment is surgical, i.e. reconstruction of the medial patellofemoral ligament recreating the medial patella-stabilizing structures. If the dysplasia is severe, tuberositas tibiae-osteotomy and trochlea plastic can correct a lateral tracking of the knee joint. Generally, patella-stabilizing surgery is successful with a reluxation rate of only a few per cent.

Primary patellar dislocations without surgical stabilization or recurrence: how well are these patients really doing?

PURPOSE

While a significant research has gone into identifying patients at highest risk of recurrence following primary patellar dislocation, there has been little work exploring the outcomes of patients who do not have a recurrent patellar dislocation. We hypothesize that patients without recurrent dislocation episodes will exhibit significantly higher KOOSs than those who suffer recurrent dislocations, but lower scores than published age-matched normative data.

METHODS

A retrospective review of patients with nonoperatively treated primary lateral patellar dislocations was carried out, and patients were contacted at a mean of 3.4 years (range 1.3-5.5 years) post-injury. Information regarding subsequent treatment and recurrent dislocations along with patient-reported outcome scores and activity level was collected.

RESULTS

One hundred and eleven patients (29.8 %) of 373 eligible patients agreed to study participation, seven of whom were excluded because they underwent subsequent patellar stabilization surgery on the index knee. Seventy-six patients (73.1 %) reported no further dislocation events, and the mean KOOS subscales at follow-up were: symptoms-80.2 ± 18.8, pain-81.8 ± 16.2, ADL-88.7 ± 15.9, sport/recreation-72.1 ± 24.4, and QOL-63.9 ± 23.8 at a mean follow-up of 3.3 years (range 1.3-5.5 years). No significant differences in any of the KOOS subscales were noted between these patients and the group that reported recurrent patellar dislocations. Only 26.4 % of the patients without further dislocations reported they were able to return to desired sport activities without limitations following their dislocation.

CONCLUSION

Patients who do not report recurrent patellar dislocations following nonoperative treatment of primary patellar dislocations are in many cases limited by this injury 3 years following the initial dislocation event.

LEVEL OF EVIDENCE

Retrospective cohort study, Level III.

Predictors of Recurrent Patellar Instability in Children and Adolescents After First-time Dislocation

BACKGROUND

Patellar dislocations are one of the most common knee injuries in children and adolescents and are challenging to treat. Recurrence rates are relatively high and many patients have functional limitations, even in the absence of a recurrent instability episode. The purpose of this study was to examine the risk factors in patients with first-time patellofemoral dislocations to develop a prediction model of recurrence.

METHODS

A single institution retrospective review of all patients with a first-time patellofemoral dislocation from 2002 to 2013 was performed. Demographic risk factors (age, sex, laterality, mechanism of injury, and history of contralateral patellar dislocation) and radiographic risk factors (increased patella height, trochlear dysplasia, and skeletal immaturity) were examined. Patella height was measured using Caton-Deschamps index (CDI). Trochlear dysplasia was assessed using the 2-grade Dejour classification and skeletal immaturity was assessed based on the distal femur and proximal tibia physis (open, closing, or closed).

RESULTS

In total, 266 knees in 250 patients were included in the study. Of these, 222 (83.5%) were treated nonoperatively and 44 (16.5%) were treated surgically. Of the knees treated nonoperatively, 77 (34.7%) had a recurrence. Significant risk factors for recurrence on univariate analysis were age 14 years and below, history of contralateral patellar dislocation, trochlear dysplasia, skeletal immaturity, and a CDI>1.45. Multivariate analysis was performed and trochlear dysplasia and skeletal immaturity were the most significant factors with odds ratios of 3.56 and 2.23, respectively. The presence of all 4 multivariate risk factors (CDI>1.45, history of contralateral patellar dislocation, trochlear dysplasia, and skeletal immaturity) had a predicted risk of recurrence of 88%. The presence of any 3 risk factors had a predicted risk of about 75% and the presence of any 2 risk factors had a predicted risk of about 55%.

CONCLUSIONS

Trochlear dysplasia, skeletal immaturity, CDI>1.45, and a history of contralateral patellar dislocation were all significant risk factors for recurrence in patients with first-time patellar dislocations. A predictive model for calculation of recurrence risk was developed for any combination of the different risk factors. This information is useful when counseling patients and their families after first-time patellar dislocation about prognosis and potential outcomes.

LEVEL OF EVIDENCE

Level IV-retrospective case series.

Surgical versus conservative management of acute patellar dislocation in children and adolescents: a systematic review

PURPOSE

The goal of this study was to perform a comparative review to determine whether there is a significant difference in the rate of repeat dislocation and clinical outcome between surgical and conservative management of acute patellar dislocation in children and adolescents.

METHODS

A systematic review of the MEDLINE database was performed. English-language clinical outcome studies with a primary outcome/treatment specific to acute patella dislocation in a paediatric population were included. Eleven studies met inclusion criteria; Chi-square analysis, independent t tests and weighted mean pooled cohort statistics were performed where appropriate.

RESULTS

A total of 470 conservatively managed and 157 operatively treated knees were included. Conservatively managed patients were on average 17.0 years and had a mean follow-up of 3.9 years; surgically managed patients were on average 16.1 years and had a mean follow-up of 4.7 years. Conservatively managed knees had a 31% rate of recurrent dislocation rate compared to 22% in surgical knees (p = 0.04). Trochlear dysplasia and skeletal immaturity confer greater risk for recurrent instability. Surgical treatment may provide clinically important quality of life and sporting benefit.

CONCLUSIONS

Surgical treatment of first time patella dislocation in children and adolescents is associated with a lower risk of recurrent dislocation and higher health-related quality of life and sporting function. There is a paucity of evidence on MPFL reconstruction for first time traumatic patella dislocation in this population.

LEVEL OF EVIDENCE

IV.

Is surgical treatment better than conservative treatment for primary patellar dislocations? A meta-analysis of randomized controlled trials

BACKGROUND

Despite several randomized controlled trials comparing operative to nonoperative management of primary patellar dislocation, the optimal management of this condition remains a subject of controversy. The aim of this study was to compare surgical to conservative treatment of outcomes for primary patellar dislocation by meta-analysis all the relative randomized controlled trials.

STUDY DESIGN

Meta-analysis.

METHODS

After searching multiple online databases (MEDILINE, EMBASE, CLINICAL, OVID, BISOS and Cochrane registry of controlled clinical trials), eight randomized controlled trials including 430 patients were meta-analyzed in which operative treatment was compared with non-operative treatment for primary patellar dislocation. Outcomes evaluated were redislocation rate, Kujala score, episode of instability, Tegner activity score, Hughston visual analog score (VAS) and patient satisfaction.

RESULTS

Outcomes on recurrent patellar dislocation (P = 0.004) and Hughston VAS (P = 0.03) were statistically significant in favor of operative management. Tegner activity score (P < 0.00001) was significantly higher in favor of conservative treatment, though only a few studies were identified. There was no significant difference between the two treatments regarding episode of instability (P = 0.41), Kujala score (P = 0.32) or patient satisfaction (P = 0.49).

CONCLUSION

Surgical treatment may be better than conservative treatment for patients with primary patellar dislocation on incidence of redislocation. However, since these findings are built on a limited number of studies available, well-designed, multicenter clinical trials with long-term follow-up are required to provide more solid evidence concerning optimal strategies.

Medial patellar subluxation: diagnosis and treatment

Medial patellar subluxation is a poorly recognized clinical condition characterized by chronic anterior knee pain that is exacerbated with knee flexion. Additional symptoms include instability, limited knee motion, and pain with squatting and stair climbing. Full characterization of the patient's knee pain requires an accurate history and physical examination. Diagnosis is typically confirmed during diagnostic arthroscopy. When nonsurgical management (eg, physical rehabilitation, patella-stabilizing bracing) fails, surgery (eg, medial retinacular release, lateral retinacular imbrication, newer techniques to repair or reconstruct the lateral retinaculum/lateral patellofemoral ligament) can lead to good results. Further study is needed to confirm current understanding of medial patellar subluxation and to better define treatment options and prevention strategies.

Closed Reduction of Subacute Patellar Dislocation Using Saline Joint Insufflation: A Technical Trick

Patellar dislocations often spontaneously reduce or are reduced easily by experienced professionals. However, some dislocations can prove difficult to reduce and may require sedation or operative management. Our case report suggests an alternative method to facilitate reduction of patellar dislocations. Our technical trick involves insufflation of the knee joint with sterile normal saline, resulting in improved clearance of the patella over the femoral condyles. This low-risk technique can aid in the reduction of a dislocated patella and save the patient from unnecessary sedation or a surgical operation.

[Case-control study on therapeutic effects between arthroscopic medial retinaculum plication and plaster external fixation for the treatment of acute patella dislocation]

OBJECTIVE

To compare therapeutic effects between arthroscopic medial retinaculum plication and plaster external fixation for the treatment of acute patellar dislocation.

METHODS

From February 2006 to October 2012,29 patients with acute patellar dislocation were divided into two groups: operation group and non-operation group. The patellar dislocation duration was 2 weeks. In operation group, there were 7 males and 10 females, with an average age of (16.2 ± 6.2) years old, and the patients were treated with arthroscopic medial retinaculum plication. In non-operation group, there were 5 males and 7 females,with an average age of (16.3 ± 5.0) years old,and the patients were treated with plaster external fixation. The Kujala scores, patellar tilt angle measured on CT film, apprehension test and recurrence rate of patellar instability were observed before and 1 year after treatment.

RESULTS

In operation group, the pre-treatment and post-treatment patellar tilt angles had no statistical difference, but the post-treatment Kujala score was lower than that of pre-treatment; while in non-operation group, the post-treatment patellar tilt angle was larger than that of pre-treatment, and the post-treatment Kujala score was lower than that of pre-treatment. At 1 year after treatment, the patellar tilt angle (21.2 ± 5.3) of patients in non-operation group was larger than (13.5 ± 3.5) of operation group, and the Kujala score 73.3 ± 10.5 of patient in non-operation group was lower than 84.1 ± 5.6 of operation group.

CONCLUSION

During 1 year after operation, arthroscopic medical retinaculum plication is a more effective treatment for acute patellar dislocation compared with plaster external fixation.

Surgical versus non-surgical interventions for treating patellar dislocation

BACKGROUND

Patellar dislocation occurs when the patella disengages completely from the trochlear (femoral) groove. Following reduction of the dislocation, conservative (non-surgical) rehabilitation with physiotherapy may be used. Since recurrence of dislocation is common, some surgeons have advocated surgical intervention rather than non-surgical interventions. This is an update of a Cochrane review first published in 2011.

OBJECTIVES

To assess the effects (benefits and harms) of surgical versus non-surgical interventions for treating people with primary or recurrent patellar dislocation.

SEARCH METHODS

We searched the Cochrane Bone, Joint and Muscle Trauma Group's Specialised Register, the Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, AMED, CINAHL, ZETOC, Physiotherapy Evidence Database (PEDro) and a variety of other literature databases and trial registries. Corresponding authors were contacted to identify additional studies. The last search was carried out in October 2014.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled clinical trials evaluating surgical versus non-surgical interventions for treating lateral patellar dislocation.

DATA COLLECTION AND ANALYSIS

Two review authors independently examined titles and abstracts of each identified study to assess study eligibility, extract data and assess risk of bias. The primary outcomes we assessed were the frequency of recurrent dislocation, and validated patient-rated knee or physical function scores. We calculated risk ratios (RR) for dichotomous outcomes and mean differences MD) for continuous outcomes. When appropriate, we pooled data.

MAIN RESULTS

We included five randomised studies and one quasi-randomised study. These recruited a total of 344 people with primary (first-time) patellar dislocation. The mean ages in the individual studies ranged from 19.3 to 25.7 years, with four studies including children, mainly adolescents, as well as adults. Follow-up for the full study populations ranged from two to nine years across the six studies. The quality of the evidence is very low as assessed by GRADE (Grading of Recommendations Assessment, Development and Evaluation Working Group) criteria, with all studies being at high risk of performance and detection biases, relating to the lack of blinding.There was very low quality but consistent evidence that participants managed surgically had a significantly lower risk of recurrent dislocation following primary patellar dislocation at two to five years follow-up (21/162 versus 32/136; RR 0.53 favouring surgery, 95% confidence interval (CI) 0.33 to 0.87; five studies, 294 participants). Based on an illustrative risk of recurrent dislocation in 222 people per 1000 in the non-surgical group, these data equate to 104 fewer (95% CI 149 fewer to 28 fewer) people per 1000 having recurrent dislocation after surgery. Similarly, there is evidence of a lower risk of recurrent dislocation after surgery at six to nine years (RR 0.67 favouring surgery, 95% CI 0.42 to 1.08; two studies, 165 participants), but a small increase cannot be ruled out. Based on an illustrative risk of recurrent dislocation in 336 people per 1000 in the non-surgical group, these data equate to 110 fewer (95% CI 195 fewer to 27 more) people per 1000 having recurrent dislocation after surgery.The very low quality evidence available from single trials only for four validated patient-rated knee and physical function scores (the Tegner activity scale, KOOS, Lysholm and Hughston VAS (visual analogue scale) score) did not show significant differences between the two treatment groups.The results for the Kujala patellofemoral disorders score (0 to 100: best outcome) differed in direction of effect at two to five years follow-up, which favoured the surgery group (MD 13.93 points higher, 95% CI 5.33 points higher to 22.53 points higher; four studies, 171 participants) and the six to nine years follow-up, which favoured the non-surgical treatment group (MD 3.25 points lower, 95% CI 10.61 points lower to 4.11 points higher; two studies, 167 participants). However, only the two to five years follow-up included the clear possibility of a clinically important effect (putative minimal clinically important difference for this outcome is 10 points).Adverse effects of treatment were reported in one trial only; all four major complications were attributed to the surgical treatment group. Slightly more people in the surgery group had subsequent surgery six to nine years after their primary dislocation (20/87 versus 16/78; RR 1.06, 95% CI 0.59 to 1.89, two studies, 165 participants). Based on an illustrative risk of subsequent surgery in 186 people per 1000 in the non-surgical group, these data equate to 11 more (95% CI 76 fewer to 171 more) people per 1000 having subsequent surgery after primary surgery.

AUTHORS' CONCLUSIONS

Although there is some evidence to support surgical over non-surgical management of primary patellar dislocation in the short term, the quality of this evidence is very low because of the high risk of bias and the imprecision in the effect estimates. We are therefore very uncertain about the estimate of effect. No trials examined people with recurrent patellar dislocation. Adequately powered, multi-centre, randomised controlled trials, conducted and reported to contemporary standards, are needed. To inform the design and conduct of these trials, expert consensus should be achieved on the minimal description of both surgical and non-surgical interventions, and the anatomical or pathological variations that may be relevant to both choice of these interventions and the natural history of patellar instability. Furthermore, well-designed studies recording adverse events and long-term outcomes are needed.

Effectiveness of Fulkerson Osteotomy with Femoral Nerve Stimulation for Patients with Severe Femoral Trochlear Dysplasia

BACKGROUND

Patients with femoral trochlear dysplasia are at risk for chronic recurrent patellofemoral dislocations, with extreme cases often requiring a surgical procedure. Anteromedialization of the tibial tubercle with intraoperative femoral nerve stimulation and concurrent medial patella-femoral ligament (MPFL) reconstruction is a previously reported method of maximizing patello-femoral congruency. We hypothesize the Fulkerson osteotomy with intraoperative femoral nerve stimulation and concurrent MPFL reconstruction in patients with severe trochlear dysplasia provides equivalent postoperative clinical outcomes to the same procedure in patients with low level trochlear dysplasia.

METHODS

48 knees underwent Fulkerson osteotomy with intraoperative femoral nerve stimulation and concurrent MPFL reconstruction for recurrent lateral patellar dislocations. MRI, surgeon intraoperative assessment, and X-ray were used to assess degrees of trochlear dysplasia; inter-observer and intra-observer error were measured. The knees positive for severe dysplasia on MRI, intraoperative assessment, and X-ray were considered as a comparison cohort to the rest of the study population. We considered postoperative dislocation events and patellar tracking kinematics as outcome measures. Independent student t tests and Fisher exact tests were used to evaluate differences between groups. Significance was set at P<0.05.

RESULTS

11 knees were positive for severe dysplasia (SD) by combined MRI, surgeon intraoperative assessment, and X-ray with the remaining 37 knees categorized as low dysplasia (LD). No patients in either group exhibited apprehension or required re-operation. Mean sulcus angle in the SD group was 175.8 +-2.45 degrees (95% CI 171.0-180.6); the LD group mean sulcus angle was 154.3 +- 0.98 degrees (95% CI 152.4-156.2) (P<.001). Postoperatively there was no significant difference in dislocation events between the SD group (0/11) and the LD group (2/37) (P>0.999). Patellar maltracking decreased in both groups and there were no significant differences in estimates of patellofemoral congruency between the SD (2/11) and LD (8/37) (P>0.999) groups.

CONCLUSION

The Fulkerson osteotomy with femoral nerve stimulation aimed at maximizing patellofemoral congruency may be an equally effective procedure for patients with either severe or mild trochlear dysplasia.

LEVEL OF EVIDENCE

Level III, Retrospective comparative study.

Patellar instability

Patella instability can cause significant pain and functional limitations. Several factors can predispose to patella instability, such as ligamentous laxity, increased anterior TT-TG distance, patella alta, and trochlear dysplasia. Acquired factors include MPFL injury or abnormal quadriceps function. In many cases, first-time dislocation can successfully be managed with physical therapy and other nonoperative management; however, more than one dislocation significantly increases the chance of recurrence. Surgical management can improve stability, but should be tailored to the injuries and anatomic risk factors for recurrent dislocation. Isolated lateral release is not supported by current literature and increases the risk of iatrogenic medial instability. Medial repair is usually reserved for patients with largely normal anatomy. MPFL reconstruction can successfully stabilize patients with medial soft tissue injury but is a technically demanding procedure with a high complication rate and risks of pain and arthrosis. Tibial tubercle osteotomy can address bony malalignment and also unload certain articular cartilage lesions while improving stability. Trochleoplasty may be indicated in individuals with a severely dysplastic trochlea that cannot otherwise be stabilized. A combination of procedures may be necessary to fully address the multiple factors involved in causing pain, loss of function, and risk of recurrence in patients with patellar instability.

[Patella instability]

In respect to the risk of recurrent patella instability, new biomechanical factors have been ruled out, and among these trochlear dysplasia is the most important single factor. The algorithm for operative intervention should be based upon X-rays and MRI scans. Medial implication is considered obsolete and distal realignment as well as lateral release procedures should be minimized, based upon deteriorating results. Reconstruction of medial structures becomes increasingly frequent, based upon good results, however, in cases of higher degree of trochlear dysplasia, trochleoplasty should be considered.

[Clinical significance of Q-angle under different conditions in recurrent patellar dislocation]

OBJECTIVE

To investigate the clinical significance of Q-angle measuring under different conditions in female recurrent patellar dislocation female patients.

METHODS

Between August 2012 and March 2013, 10 female patients (11 knees) with recurrent patellar dislocation were collected as trial group; 20 female patients (20 knees) with simple meniscus injury were collected as control group at the same time. Q-angle was measured in extension, 30 degrees flexion, 30 degrees flexion with manual correction, and surgical correction in the trial group, and only in extension and 30 degrees flexion in the control group. Then the difference value of Q-angle between extension and 30 degrees flexion (Q-angle in extension subtracts Q-angle in 30 flexion) were calculated. Independent sample t-test was used to analyze Q-angle degrees in extension, 30 degrees flexion, and the changed degrees of 2 groups. The Q-angle between manual correction and surgical correction of the trial group was analyzed by paired t-test.

RESULTS

The Q-angle in extension, Q-angle in 30 degrees flexion, and difference value of Q-angle between extension and 30 degrees flexion were (17.2 +/- 3.6), (14.3 +/- 3.0), and (2.9 +/- 1.9) degrees in the trial group and were (15.2 +/- 3.4), (14.4 +/- 3.5), and (0.8 +/- 1.7) degrees in the control group. No significant difference was found in Q-angle of extension or Q-angle of 30 degrees flexion between 2 groups (P > 0.05), but the difference value of Q-angle between extension and 30 degrees flexion in the trial group was significantly larger than that in the control group (t = 3.253, P = 0.003). The Q-angle in 30 degrees flexion with manual correction and surgical correction in the trial group was (19.8 +/- 3.4) degrees and (18.9 +/- 3.8) degrees respectively, showing no significant difference (t = 2.193, P = 0.053).

CONCLUSION

When a female patient's Q-angle in 30 degrees flexion knee changes obviously compared with Q-angle in extension position, recurrent patellar dislocation should be considered. For female patients with recurrent patellar dislocation, the preoperative Q-angle in 30 degrees flexion with manual correction should be measured, which can help increasing the accuracy of evaluation whether rearrangement should be performed.

Patellar instability

Patellar instability is a complex pathoanatomical phenomenon that requires an intricate understanding in order to properly treat patients. Often, the etiology of this entity is multifactorial, combining a series of physiologic and anatomic variables. A thorough history and physical as well as correct radiographic examinations are critical in both establishing the diagnosis and instituting the correct treatment. Non-operative management of recurrent instability has a high failure rate. Current operative techniques have been shown to be instrumental in correcting anatomic abnormalities, reducing symptoms of instability, and giving patients an appropriate chance of returning to their previous level of activity.

Lateral patellar dislocation: mechanism of disease, radiographic presentation, and management

Lateral patellar dislocation is a common injury occurring in young active adults. The mechanism is that of twisting injury to the knee on a planted foot with valgus stress. Several predisposing factors, including femoral trochlear dysplasia, patella alta, and lateralization of the tibial tuberosity, contribute to patellar instability and lateral patellar dislocation. Magnetic resonance (MR) imaging of the knee is the modality of choice to evaluate underlying bone contusion patterns, associated soft-tissue injuries, and additional complex ligamentous and osteochondral injuries, many of which are not apparent on conventional radiographs.

Cartilage lesions in patellofemoral dislocations: incidents/locations/when to treat

Patellofemoral (PF) dislocations are frequently associated with chondral injury. Chondral and osteochondral lesions are often associated with traumatic (high-energy) PF dislocations, whereas atraumatic (low-energy) PF dislocations in patients with significant PF risk factors have a much lower incidence of osteochondral damage. This article provides a historical overview and delineates the current state of radiographic and clinical outcomes of osteochondral lesions after PF dislocation. The importance of understanding risk factors of redislocation is emphasized, and the current treatment options for these cartilage lesions associated with PF dislocation are briefly summarized.

[Ligament which deserves attention--medial patellofemoral ligament]

There has been increasing interest in investigating the medial patellofemoral ligament (MPFL) during the last fifteen years. This is due to the recognition of the MPFL as the primary static soft-tissue restraint to lateral patellar displacement and the association of MPFL injury with primary traumatic patellar dislocation. The MPFL often heals poorly and thus rarely regains its full function. Numerous surgical techniques have been described for reconstruction of this important structure. This paper reviews the relevant anatomy and biomechanics, published reconstruction options, and describes the surgical technique performed at our institution--that of using a quadriceps autograft to reconstruct the MPFL.

Surgical versus non-surgical interventions for treating patellar dislocation

BACKGROUND

Patellar dislocation occurs when the patella disengages completely from the trochlear (femoral) groove. Following reduction of the dislocation, conservative rehabilitation with physiotherapy may be used. Since recurrence of dislocation is common, some surgeons have advocated surgical intervention in addition to rehabilitation.

OBJECTIVES

The purpose of this review was to assess the clinical and radiological outcomes of surgical, compared with non-surgical, interventions for treating people with primary or recurrent patellar dislocation.

SEARCH METHODS

We searched the Cochrane Bone, Joint and Muscle Trauma Group's Specialised Register, the Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, AMED, CINAHL, ZETOC, Physiotherapy Evidence Database (PEDro), and a variety of other literature databases and trial registries. Corresponding authors were contacted to identify additional studies. Date searched: August 2010.

SELECTION CRITERIA

Eligible for inclusion were randomised and quasi-randomised controlled clinical trials evaluating surgical versus non-surgical interventions for treating lateral patellar dislocation.

DATA COLLECTION AND ANALYSIS

Two reviewers independently examined titles and abstracts of each identified study to assess study eligibility, extract data and assess risk of bias. Primary outcomes assessed were the frequency of recurrent dislocation, and validated patient-rated knee or physical function scores. When appropriate, data were pooled. Risk ratios were calculated for dichotomous outcomes, and mean differences for continuous outcomes.

MAIN RESULTS

Five studies (339 participants) were included. All studies had methodological shortcomings, especially the two quasi-randomised trials that presented a high risk for selection bias. Follow-up was a minimum of two years in two studies and between five and seven years in three studies. There was no significant difference between surgical and non-surgical management of primary (first-time) patellar dislocation in the risk of recurrent dislocation (47/182 versus 53/157; risk ratio 0.81, 95% confidence interval 0.56 to 1.17; 5 trials), Kujala patellofemoral disorder scores (mean difference 3.13, 95% confidence interval -7.34 to 13.59; 5 trials) nor the requirement for subsequent surgery (risk ratio 1.09, 95% CI 0.72 to 1.65; 3 trials). Adverse events were reported by one trial, citing four major complications that occurred in the surgical group. No randomised controlled trials have assessed populations with recurrent patellar dislocation.

AUTHORS' CONCLUSIONS

There is insufficient high quality evidence to confirm any significant difference in outcome between surgical or non-surgical initial management of people following primary patellar dislocation, and none examining this comparison in people with recurrent patellar dislocation. Adequately powered randomised, multi-centre controlled trials, conducted and reported to contemporary standards are recommended.

[Patellar luxation in a young adult]

Damage of the medial patellofemoral ligament in connection with traumatic patellar luxation is important to recognize. Repair or reconstruction of this structure prevents the recurrence of patellar luxation. Anatomy of the patellofemoral joint, on the other hand, has significant effect on patellar stability, whereby the same procedure is not appropriate for everybody. Some patients with traumatic patellar luxation will benefit from early-stage surgical treatment, some heal equally well by conservative treatment. Previous problems of the treatment of patellar luxation, i.e. poorly predictable recovery and relatively poor results of the surgery, have turned into challenges in the selection of individual therapy and timing of surgery.

Patellar instability

Patellar instability is a generic term that is used to describe patellar dislocation, patellar subluxation, and general symptomatic instability. Patellofemoral instability is a relatively difficult condition to treat; accurate management of the condition should take into account the anatomy of the joint and its stabilizing structures. The goal of any treatment should be to restore the normal anatomy of the joint. It is important to understand the basic anatomy and biomechanics of this condition, the classification of different types of patellar instability, varying presentations, and diagnostic techniques and criteria, including the types of imaging studies that can be useful in determining the ultimate course of treatment.

Patellofemoral instability

This review describes the normal patellofemoral joint and detail the mechanism and anatomic elements that predispose patients to patellar instability. The treatment options for both acute and chronic injuries are described and the rationale behind their approach to this problem is explained. In general, most acute dislocations should be treated nonoperatively unless the instability is associated with an osteochondral injury. Chronic dislocators should be treated based on an understanding of the patient's individual reason for recurrent instability. This is achieved with a thorough history, physical examination, and imaging studies. This information can help the clinician select the most appropriate proximal and or distal procedure.

An evaluation of the clinical tests and outcome measures used to assess patellar instability

A literature review was undertaken to determine which clinical tests and outcome measures have been described to diagnose and evaluate patellar instability, and to assess the literature examining the sensitivity and specificity of these diagnostic tests, or the reliability, validity and responsiveness of the outcome measures identified. An electronic search was undertaken using standard databases as well as a hand search of specialist journals, reference lists and local medical libraries. All English language publications describing and/or evaluating diagnostic tests and outcome measures for patellar instability patients were included. On review, 104 papers and 64 textbooks were included. Eighteen diagnostic tests and 10 outcome measures were identified. Of these only five diagnostic tests (Bassett's sign; apprehension test; gravity subluxation test; clinical assessment of the tibial tubercle to trochlear groove value; Q-angle) and seven outcome measures (modified International Knee Documentation Committee knee ligament standard evaluation form; Kujala anterior knee pain scale; Fulkerson knee instability scale; Lysholm knee scoring scale; Tegner activity level scale; Short Form-36; Musculoskeletal Function Assessment injury and arthritis survey) had been assessed for accuracy in five studies. The sensitivity, specificity, reliability or validity, of these tests remains unclear for this patient population. Further work is needed to assess the appropriateness of the identified tests and outcomes for patellar instability cohorts.

Rehabilitation and Nonoperative Treatment of Patellar Instability

Patellofemoral instability can be a difficult condition for clinicians to manage. Differentiation needs to be made as to whether the problem is an acute injury where a traumatic incident has usually precipitated the dislocation or whether the problem is a recurrent instability where the patellofemoral joint is unstable during everyday activities. This review defines instability, discusses the factors affecting instability, and provides assessment procedures and nonoperative intervention strategies for the clinician.

An Algorithm Guiding the Evaluation and Treatment of Acute Primary Patellar Dislocations

Primary patellar dislocation continues to be a common problem facing clinicians today. These injuries are associated with significant morbidity and a substantial recurrence rate. A myriad of operative and nonoperative options have been described to treat these injuries though the evidence-based literature is sparse. As a result, much controversy exists regarding the ideal management of the primary patellar dislocation. This article reviews the literature on this topic, from the initial examination and management to definitive treatment. Furthermore, an algorithm is presented to help the clinician approach and treat these patients.

Luxación intra-articular de rótula

The case of a patient aged 73 years who, following an accidental fall on a staircase, suffered an acute intraarticular dislocation in the left knee-cap is presented. This exceptional dislocation presented incarceration of the proximal kneecap pole in the femoral intercondylar groove. A reduction was carried out under general anaesthetic due to pain and muscular contraction in the attempts at reduction without anaesthetic. We made a surgical check that ruled out associated lesions to the extensor apparatus, soft parts, joint structures and osteophytes. The patient presented advanced arthrosis, above all femoral-patellar. Following two weeks of immobilisation, the patient restarted mobility. There has been no relapse or other type of complication.

[Patella dislocation]

Patella dislocation is a classical injury affecting teenagers. In 2/3 of cases, it occurs in sports activities. It is often a benign trauma which happens in a patello-femoral dysplasia context, leading to dislocation and reccurence if nothing is done to correct the defaults. Radiographic and scanner examinations allow to measure the dysplasia parameters and think about its correction. With MRI documentation, capsulo-ligamentous and cartilaginous lesions can be identified and their surgical repair can be discussed. When the dislocation occurs in a normal anatomical context, conservative therapy is still indicated.

Femoral Neuropathy Due to Patellar Dislocation in a Theatrical and Jazz Dancer: A Case Report

This case report describes a teenage female, high-level modern dancer who suffered multiple left patellar dislocations. Her history is atypical in that after her fifth dislocation, her recovery was hindered secondary to persistent weakness and atrophy of her quadriceps out of proportion to disuse alone. Electrodiagnostic studies and magnetic resonance imaging showed evidence of a subacute femoral neuropathy correlating chronologically with her most recent patellar dislocation. This case suggests that further diagnostic study may be warranted in patients with persistent quadriceps weakness or atrophy after a patellar dislocation, because this may suggest the presence of a femoral neuropathy. This is important because the strength training goals and precautions differ in disuse atrophy and a neuropathy. We believe this is the first reported case of a femoral neuropathy associated with the mechanism of a patellar dislocation.

Superior dislocation of the patella. Case report and review of literature

Superior dislocation of the patella is a rare diagnosis, which usually occurs after a trivial trauma. It usually requires manipulation with analgesics or may even need anaesthesia. We report a case of spontaneous reduction of the dislocation, which lead us to believe that this may be more common in the community than has been reported.

Patellar tendonitis and patellar dislocations

Common sports injuries, such as patellar tendonitis and patellar dislocation, can be treated either surgically or with rehabilitation and physical therapy. Most patients with patellar tendonitis will respond well to conservative measures; however, some recalcitrant cases will require surgical intervention. To date, the literature is not able objectively to identify the patients best suited to surgery. Likewise, in the case of patellar dislocations, it is still unclear which patients respond best to conservative therapy and which respond best to surgical treatment, although evidence continues to accumulate. A practical approach to this problem can be deduced from the available evidence, but more well-designed clinical trials are needed for the establishment of definitive treatment protocols.

Vertical patellar dislocation: a case report

Dislocation of the patella around the vertical axis is rare. Previous reports suggest reduction requires general anaesthesia and occasionally open reduction is necessary. We describe a case of dislocation of the patella around its vertical axis with impaction in the intercondylar notch of the femur following minor trauma. Successful reduction was achieved without the need for general anaesthesia.

Intra-articular dislocation of the patella with incomplete rotation--two case reports and a review of the literature

Intra-articular dislocation of the patella is a rare clinical condition. Only forty-five cases have been reported. Most of them were encountered in adolescents and required an open reduction. We report two cases in an older age group with an incomplete rotation of the patella, which were successfully treated by closed reduction. We discuss the literature and suggest that the management depends on the degree of patellar rotation.

Traumatic patellar dislocation in children and adolescents: treatment update and literature review

PURPOSE OF REVIEW

Traumatic patellar dislocation in children and adolescents is a complex problem resulting from a range of anatomic and mechanical conditions. A careful review of the literature demonstrates certain risk factors that predispose children to recurrent dislocation. With this understanding, these conditions can be managed more aggressively in the hope of an improved outcome. Additionally, a vast number of surgical procedures to correct patellar instability have been described, and recent cadaveric studies are now guiding surgical interventions.

RECENT FINDINGS

Risk factors for recurrent dislocation may include various skeletal abnormalities, increased quadriceps angle, generalized ligamentous laxity, and family history. Recent anatomic and biomechanical studies have demonstrated that the medial patellofemoral ligament and the vastus medialis obliquus are the primary restraints to lateral translation and ultimately dislocation of the patella. Management should therefore be directed both at correcting anatomic abnormalities when indicated and at reconstruction of medial restraints to patellar tracking.

SUMMARY

The recommendation for management of a traumatic patellar dislocation in a skeletally immature patient is initially conservative, emphasizing early motion and quadriceps strengthening. However, in patients for whom conservative management has failed or who are at particularly high risk for dislocation and require surgical intervention, repair or reconstruction of the medial patellofemoral ligament is the treatment of choice. Recent works have included investigation of less invasive techniques in children.

[Intra-articular, horizontal dislocation of the patella]

We present an interesting case of intra-articular, horizontal dislocation of an adult patella without rupture of the quadriceps muscle tendon or a patellar fracture.