Current concepts of lateral patella dislocation

Influence of rupture patterns of the medial patellofemoral ligament (MPFL) on the outcome after operative treatment of traumatic patellar dislocation

PURPOSE

Patellar dislocation usually occurs to the lateral side, leading to ruptures of the medial patellofemoral ligament (MPFL) in about 90 % of all cases. Reliable prognostic factors for the stability of the patellofemoral joint after MPFL surgery and satisfaction of the patient have not been established as yet.

METHODS

This multicentric study retrospectively included 40 patients with a mean age of 22.4 ± 8.1 years (range 9-48) from 5 German Trauma Departments with first-time traumatic patellar dislocation and operative treatment. Surgery was limited to soft tissue repairs, and a preoperative magnetic resonance imaging (MRI) was performed in all cases. Evaluation of the MRI included sulcus angle, dysplasia of the trochlea, depth and facet asymmetry of the trochlea, Insall-Salvati index, Tibial tuberosity to trochlear groove (TTTG) distance, and rupture patterns of the MPFL. Patients were interrogated after 2 years about recurrent dislocation, satisfaction, and the Kujala score.

RESULTS

Trochlea facet asymmetry was significantly lower in patients with redislocation (23.5 ± 18.8) than in patients without redislocation (43.1 ± 16.5, p = 0.03). Patients with a patellar-based rupture were significantly younger (19.5 ± 7.2 years) than patients without patellar-based rupture (25.4 ± 8.1 years, p < 0.02). Patients with femoral-based ruptures were significantly older (25.7 ± 9.2 years) than patients without femoral-based rupture (19.7 ± 6.1 years, p < 0.02), and had a significantly higher TTTG distance (10.2 ± 6.9 vs. 4.5 ± 5.5, p < 0.02). Patients with incomplete ruptures of the MPFL had a significantly lower Insall-Salvati index (1.2 ± 0.2 vs. 1.4 ± 0.2, p = 0.05). The Kujala score in patients with redislocations was significantly lower (81.0 ± 10.5 points) than in patients without redislocation (91.9 ± 9.2 points, p < 0.02).

CONCLUSION

Younger patients more often sustain patellar-based ruptures following first-time traumatic patella dislocation, while older patients more often sustain femoral-based ruptures of the MPFL. Incomplete MPFL ruptures are correlated with lower Insall-Salvati indices. Low trochlear facet asymmetry is correlated with higher rates of redislocation. These results may be of relevance for the operative and postoperative treatment in the future.

LEVEL OF EVIDENCE

Prognostic study, Level IV.

Operative vs conservative treatment of traumatic patellar dislocation: results of a prospective randomized controlled clinical trial

INTRODUCTION

Patellar dislocation is a common knee injury with mainly lateral dislocations, leading to ruptures of the medial patellofemoral ligament in most of the cases. Even though several prognostic factors for patellofemoral instability have been identified so far, the appropriate therapy for patients with patellar dislocation remains a controversial issue. The purpose of this study was to compare the outcome after conservative or operative treatment in patients after first-time patellar dislocation.

PATIENTS AND METHODS

This randomized controlled clinical trial was designed multicentric including patients from six German orthopaedic and trauma departments. Twenty patients with a mean age of 24.6 years with first-time traumatic patella dislocation were included and randomized into either a conservative arm or an operative arm. Plain X-ray images of the knee joint (a.p. and lateral view and tangential view of both patellae) were performed in all cases prior to therapy to exclude osteochondral fragments requiring refixation. An MRI was recommended, but not compulsory. Patients were consulted after 6, 12, and 24 months with a questionnaire including the criteria of the Kujala score, recurrent dislocation, and satisfaction.

RESULTS

The mean Kujala score of the conservative vs operative treatment group was 78.6 vs 80.3 after 6 months (p = 0.842), 79.9 vs 88.9 after 12 months (p = 0.165), and 81.3 vs 87.5 after 24 months (p = 0.339). Redislocation rate after 24 months was 37.5 % in the conservative group and 16.7 % in the operative group (p = 0.347). Due to the small number of patients that could be included, no significant difference between the groups could be detected. We see a tendency towards better results after operative treatment.

CONCLUSION

Our multicentric prospective randomized controlled trial revealed no significant difference between conservative and operative treatment for patients after first-time traumatic patellar dislocation. However, a tendency towards a better Kujala score and lower redislocation rates for patients with operative treatment was observed. The small number of patients is a limiting factor of the study, leading to results without statistical significance. A meta-analysis including other study's level I data is desirable for the future.

The influence of risk factors on clinical outcomes following anatomical medial patellofemoral ligament (MPFL) reconstruction using the gracilis tendon

PURPOSE

Patellofemoral instability is influenced by ligamentous, boney and neuromuscular factors. The most important variables are trochlea geometry, medial patellofemoral ligament (MPFL), patella height, tibial tuberosity-trochlea groove distance (TT-TG) and the extensor muscles. Treatment is complicated by these multifactorial conditions. This prospective study examined the influence of risk factors on clinical results and athletic activities where treatment was confined to ligamentous procedures only.

METHODS

Fifty patients with chronic patellofemoral instability were treated with MPFL reconstruction using an autologous gracilis tendon. Clinical data, radiographs and magnetic resonance imaging (MRI) were prospectively evaluated pre- and postoperative (minimum follow-up 12 month) to detect existing risk factors for patellofemoral instability and to evaluate clinical and sport ability scores (Kujala, Valderrabano).

RESULTS

There was a low rate of redislocation (2 %) and an average Kujala score of 87 ± 13 points postoperative. The MRI showed good integration of the reconstructed MPFL and a positive effect regarding the decrease of patella tilt (16.1° to 11.2°). A negative relationship was found between the degree of trochlear dysplasia and outcomes. 80 % of all patients returned to the same or higher level of physical activity.

CONCLUSIONS

Addressing only ligamentous factors through MPFL reconstruction leads to satisfying clinical results and low redislocation rates in most patients. In cases with a high degree of trochlear dysplasia and enlarged TT-TG, additional procedures such as trochleaplasty and tibial tuberosity transfer should be considered as well.

LEVEL OF EVIDENCE

IV.

The Lyon's sulcus-deepening trochleoplasty in previous unsuccessful patellofemoral surgery

PURPOSE

Trochleoplasty is a relatively rare operation with few published results and it remains a technically demanding procedure which requires careful patient selection. The ideal candidate for surgery remains to be elucidated, and some authors consider it as a good revision option in cases of previous unsuccessful operations for persisting patellar dislocation with underlying trochlear dysplasia. The purpose of this study is to record the results from the application of sulcus-deepening trochleoplasty in patients with trochlear dysplasia and previous unsuccessful surgery for patellar dislocation.

METHODS

Twenty-two patients (24 knees) were operated upon during the period 9/1993-9/2006; they had undergone surgery for patellofemoral instability and had persistent patellar dislocation, and were followed-up for a mean of 66 months (24-191). Trochleoplasty was performed in all patients using the same technique and rehabilitation protocol. Additional soft-tissue and bony operations were performed in every case.

RESULTS

Of all cases, 29.1% had type B and 70.9% had type D trochlear dysplasia. After trochleoplasty, no patient had a patellar re-dislocation up to the last follow-up. Pain decreased in 72% and the apprehension sign was negative in 75% of the cases (p < 0.01). Sulcus angle decreased from 153° ± 14° to 141° ± 10° (p < 0.01), TT-TG distance decreased from 16 ± 6 mm to 12 ± 2 mm (p < 0.001), and patellar tilt decreased from 31° ± 14° to 11° ± 8° (p < 0.0001). Mean pre-operative Kujala score was 44 (25-73) and at the latest follow-up it increased to 81 (53-100), (p < 0.001). At the time of final follow-up, there was no case of patellofemoral arthritis.

CONCLUSIONS

Trochlear dysplasia is a key factor in the treatment of recurrent patellar dislocation and its correction could be included in the surgical options. Sulcus-deepening trochleoplasty is an acceptable revision option for the surgical treatment of patients with persisting patellar dislocation and high-grade trochlear dysplasia.

Medial patellar retinaculum plasty versus medial capsule reefing for patellar dislocation in children and adolescents

INTRODUCTION

The purpose of this study was to evaluate the clinical effect of medial patellar retinaculum plasty for children and adolescent patients with patellar dislocation.

MATERIALS AND METHODS

A prospective study was performed between October 2005 and December 2009. Sixty-one cases of children and adolescent patients with patellar dislocation were admitted to our study. Twenty-nine patients received medial capsule reefing, of which 13 patients also received lateral retinacular release (LRR) (Group I). Thirty-two patients received medial patellar retinaculum plasty, of which 12 patients also received LRR (Group II). Preoperatively, all patients received magnetic resonance imaging (MRI) to evaluate the injury of medial patellofemoral ligament. And all patients received computed tomography (CT) scans on which the congruence angle (CA) and patellar lateral shift (PLS) could be evaluated with 30° knee flexion. Physical apprehension tests were examined and the redislocation was recorded. In addition, knee function was evaluated using the Kujala score and subjective questionnaires.

RESULTS

Patients were followed up for a mean period of 50 months (25-75 months). For the comparison between the preoperative and postoperative results, the Kujala score improved significantly from 52.3 ± 2.9 to 78.1 ± 3.6 in Group I and from 53.5 ± 3.4 to 82.2 ± 3.4 in Group II (P < 0.05). There was significant difference of CA on CT scans and PLS with a statistical difference between the two groups (P < 0.05). Results of the apprehension test showed that nine patients had patellar lateral shift exceeding 1.5 cm with a soft end point in Group I and two patients had patellar lateral shift exceeding 1.5 cm with a hard end point in Group II (P < 0.05). Moreover, the subjective questionnaire revealed a significant difference of subjective effects between two groups (P < 0.05), including 7 excellent, 10 good and 12 fair in Group I and 18 excellent, 9 good, and 5 fair in Group II.

CONCLUSION

The medial retinaculum plasty was better than medial capsule reefing in improving the subjective effects and decreasing the rate of patellar instability postoperatively in children and adolescent patients.

Patellofemoral osteoarthritis

Patellofemoral arthritis is a fairly common disease, and it has been gaining interest with increasing number of studies due to its diverse treatment methods. Patellofemoral arthritis has a broad range of management options according to the characteristics of individual diseases. Identifying whether patellofemoral arthritis is the primary cause of knee pain and is compartment arthritis is necessary for establishing an adequate treatment method. Through investigation of the literature, the issues of recent knowledge of femoropatella arthritis and the diagnosis and treatment of which were studied.

Modern management of patellar instability

Recurrent patellofemoral instability is a disabling condition, attributed to a variety of anatomical aetiologies. Trochlear dysplasia, patella alta, an increased tibial tubercle trochlear groove distance of greater than 20 mm and soft tissue abnormalities such as a torn medial patellofemoral ligament and inadequate vastus medialis obliquus are all factors to be considered. Management of this condition remains difficult and controversial and knowledge of the functional anatomy and biomechanics of the patellofemoral joint, a detailed history and clinical examination, and an accurate patient assessment are all imperative to formulate an appropriate management plan. Surgical treatment is based on the underlying anatomical pathology with an aim to restore normal patellofemoral kinematics. We summarise aspects of assessment, treatment and outcome of patellofemoral instability and propose an algorithm of treatment.

A feasibility study for a pragmatic randomised controlled trial comparing cast immobilisation versus no immobilisation for patients following first-time patellar dislocation

BACKGROUND

The purpose of this feasibility study was to begin to determine the efficacy of cylinder cast immobilisation compared to no form of immobilisation for patients following first-time patellar dislocation (FTPD).

MATERIALS AND METHODS

Participants were patients who attended a National Health Service Accident and Emergency department following a FTPD. Patients were randomised to receive immobilisation for four weeks in a cylinder cast followed by rehabilitation, versus no immobilisation and early rehabilitation. All patients were followed-up over a three month period, assessed using the Visual analogue scale for pain, Short Form-36, the Lysholm knee score and the Modified Functional Index.

RESULTS

Forty-one patients were approached to participate. Eight satisfied the pre-defined eligibility criteria and were randomised between the two groups. Whilst the results indicated a trend for superior short-term functional outcomes for those patients not immobilised compared to those immobilised following a FTPD, the small sample and baseline imbalances between the groups may have had a substantial influence on the results.

CONCLUSION

This feasibility study has indicated that the outcome measurements adopted were appropriate to answer this research question, but the assessment of return to normal activity, recurrent instability and dislocation and cost-effectiveness over a longer follow-up period is recommended. Similarly, defining a more pragmatic eligibility criteria and recruiting from multiple centres would be recommended for the definitive trial requiring a sample of 348 patients to demonstrate a statistical significant treatment effect.

Patella re-alignment in children with a modified Grammont technique

BACKGROUND AND PURPOSE

In skeletally immature patients, surgical options due to recurrent patella dislocation are limited, because bony procedures bear the risk of growth disturbances. In this retrospective study, we report the long-term functional and radiographic outcome in skeletally immature patients using the modified Grammont surgical technique.

PATIENTS

Between 1999 and 2004, 65 skeletally immature knees (49 children) were treated with a modified Grammont procedure: an open lateral release and a shift of the patella tendon insertion below the growth plate on the tuberositas tibia, allowing the tendon to medialize. At mean 8 (5.6-11) years after surgery, 58 knees in 43 patients were evaluated by clinical examination, from functional scores (Lysholm, Tegner), and from radiographs of the knees.

RESULTS

Mean Lysholm score was 82 postoperatively. Tegner score decreased from 6.2 to 5. Eight knees had a single dislocation within 3 months of surgery. 3 knees had repeated late dislocations, all with a high grade of trochlea dysplasia. 6 knees showed mild signs of osteoarthritis. No growth disturbances were observed.

INTERPRETATION

The modified Grammont technique in skeletally immature patients allows restoration of the distal patella tendon alignment by dynamic positioning. Long-term results showed that there were no growth disturbances and that there was good functional outcome. However, patients with a high grade of trochlea dysplasia tended to re-dislocate.

Characterized chondrocyte implantation in the patellofemoral joint: an up to 4-year follow-up of a prospective cohort of 38 patients

BACKGROUND

Autologous chondrocyte implantation (ACI) is an accepted treatment option for selected condylar cartilage defects in the knee. Results for patellofemoral chondral defects have been less favorable.

HYPOTHESIS

Autologous chondrocyte implantation with characterized chondrocytes will result in clinically relevant improvement in patellofemoral lesions.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients with symptomatic patellofemoral full-thickness cartilage lesions were treated with ACI using characterized chondrocytes (ChondroCelect) covered with a collagen type I membrane. Clinical outcome was assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and a visual analog scale (VAS) for pain. Responders were defined using 5 categories (≥10 points and ≥20%, 30%, 50%, 70%) based on the KOOS and VAS. Treatment failure was defined as partial loosening of more than 20% of the graft with subsequent procedures to the subchondral bone.

RESULTS

Thirty-eight patients, with a mean defect size of 4.89 cm(2) (range, 1.5-11 cm(2)), were treated for a patellar defect (n = 28), trochlear defect (n = 7), or a kissing lesion (trochlea and patella; n = 3). The minimum follow-up period was 24 months (mean, 37 months; range, 24-72 months). Treated patients showed statistically significant improvements in the KOOS (at 12, 18, 24, 36, and 48 months) and VAS (at the same time points) compared with pretreatment for each time point. Responder analysis identified approximately 84% of patients with a clinically relevant improvement greater than 10 points at 3 years. Treatment failure was observed in 5 patients. The most commonly reported adverse events were joint crepitation (n = 18) and arthrofibrosis (n = 7). No relationship could be found between clinical outcome and anatomic characteristics of the patellofemoral joint, lesion size and site, time since onset, or age. Nine patients required additional surgery: 6 because of persistent symptoms and 3 for hardware removal.

CONCLUSION

Characterized chondrocyte implantation resulted in statistically significant and clinically relevant improvement over time. These results add to the evidence demonstrating that ACI is a valuable cartilage repair technique for patellofemoral lesions.

The location of medial patellofemoral ligament injury in adolescents and children

BACKGROUND

The location of medial patellofemoral ligament (MPFL) tears has been well documented in the adult population, with most occurring at the insertion of the ligament on the adductor tubercle. It is not clear whether a difference exists in the pediatric and adolescent populations. The location of the injury has implications for treatment recommendations and planning surgical approaches. The purpose of this study is to determine whether the location of MPFL injury differs among the adult and younger populations. Our hypothesis is that the location of MPFL tears in adolescents and children is not predominantly at the adductor tubercle.

METHOD

At our institution, we retrospectively reviewed 113 children aged 5 to 17, who were surgically treated for a patellar dislocation. All patients had confirmation of a patellar dislocation or severe subluxation. Imaging studies, clinic notes, and operative notes were used to determine the location of the MPFL injury.

RESULTS

Proportion of MPFL injuries found intraoperatively at the adductor tubercle was larger than 0.5 (z test=2.97). Percentage of MPFL tears at the adductor tubercle was 73% of the cases studied.

CONCLUSIONS

The location of MPFL injuries found intraoperatively at the adductor tubercle was 73% in our series. This is slightly lower than MPFL tear location in the adult population, which has been reported to be between 80% and 100%. Our hypothesis that the location of MPFL tears in adolescents and children is not predominantly at the adductor tubercle was proven false. This study has clinical applications for treatment recommendations and planning surgical approaches for the pediatric patient with a tear of the MPFL.

LEVEL OF EVIDENCE

Level II-prognostic.

The operative management of patella malalignment

Management of patellofemoral joint pathology is challenging as a result of the unique and complex organization of static forces and dynamic factors contributing to its functional capacity. Anterior knee pain is a common musculoskeletal complaint seen daily in the practices of primary care physicians, rheumatologists, and orthopedic surgeons. The key to successful treatment lies not only in the correct diagnosis of a chondral defect, but more importantly, in the accurate identification of associated pathomechanical factors. Appreciating the pathoanatomic basis of the disease and addressing imbalances and anatomical abnormalities should guide treatment.Despite the complexity of the interplay of various components it is essential to attempt to describe patellar malalignement as a clinical entity in order to proceed with appropriate surgical management and successful outcomes. The goals of patellofemoral re- alignment surgery should be to create both a stable environment for optimal extensor mechanism performance and an appropriate load transmission for optimal cartilage wear and joint loading. In the context of this article we will review the operative management of patellofemoral malalignment; the indications for surgery, the different techniques available and the evidence regarding their effectiveness.A large number of procedures have been employed and they have all undergone various modifications over the course of the years. The majority of publications are retrospective series in poorly defined population groups. There are significant methodological inconsistencies and as a result there is lack of strong evidence base for the majority of these procedures.

A flatter proximal trochlear groove is associated with patella cartilage loss

PURPOSE

The bony articular surface contributes to a joint's congruency, and it might be a determinant of structural change. The aim of this longitudinal study was to determine (i) whether the angle of the trochlear groove is associated with the rate of loss of patella cartilage volume for 2 yr and (ii) whether this association is influenced by particular modifiable and nonmodifiable factors.

METHODS

A total of 297 community-based adults with no history of knee pathologic disease were recruited at baseline (2003-2004), and 271 of these subjects were reexamined at follow-up (2006-2007). Magnetic resonance imaging was performed at baseline and follow-up to determine the change in patella cartilage volume, whereas baseline images were used to assess trochlear groove angles. A baseline questionnaire determined participation in vigorous physical activity.

RESULTS

For every 1° increase in the proximal trochlear groove angle at baseline, there was an associated 1.12-mm3 (95% confidence interval (CI) = 0.00-2.24 mm3) increase in the annual rate of patella cartilage volume loss. There was a trend for this effect to occur for males, as well as people participating in vigorous physical activity (all P ≤ 0.07). Males who exercised vigorously were more adversely affected (5.0 mm3 per annum (95% CI = 0.5-9.4 mm3 per annum)) than males who did not exercise vigorously (0.6 mm3 per annum (95% CI = -2.1 to 3.3 mm3 per annum)).

CONCLUSIONS

A more flattened proximal trochlear groove is associated with increased patella cartilage volume loss, particularly for physically active men. Our results suggest that lifestyle factors, such as physical activity, may modify the association between joint incongruity and cartilage loss and can be further affected by subjects' characteristics such as gender. Understanding these complex interactions will help optimize strategies to maintain patellofemoral joint health.

Primary traumatic patellar dislocation

Acute traumatic patellar dislocation is a common injury in the active and young adult populations. MRI of the knee is recommended in all patients who present with acute patellar dislocation. Numerous operative and non-operative methods have been described to treat the injuries; however, the ideal management of the acute traumatic patellar dislocation in young adults is still in debate. This article is intended to review the studies to the subjects of epidemiology, initial examination and management.

[Evidence-based treatment protocol to manage patellar dislocation]

Patellar dislocation is a common knee injury with mainly lateral dislocations, leading to ruptures of the medial patellofemoral ligament in most of the cases. Reliable data and prognostic factors for stability of the patellofemoral joint and satisfaction of the patient after either conservative or operative treatment have not been established yet. Until now, there are no randomized controlled trials for recurrent patellar dislocation at all. As a synopsis of the randomized controlled trials about first-time patellar dislocation, no significant difference between operative and conservative management is evident. This applies to both children and adolescents as well as to adults. There is a clear tendency towards first-line conservative therapy after traumatic patellar dislocation. Operative treatment is only required in case of accompanying injuries like osteochondral fractures or in case of recurrent dislocations. Further prospective randomized controlled trials with standardized operative and conservative treatment and patient cohorts of sufficient size are necessary in the future.

Non-anatomic proximal realignment for recurrent patellar dislocation does not sufficiently prevent redislocation

Several operative techniques have been described for recurrent patellar dislocation. Clinical results vary depending on the procedure and indication. The present study aimed to evaluate the clinical outcome of Insall's proximal realignment for recurrent patellar dislocation at mid-term follow-up. Forty-five patients were reviewed with a mean follow-up period of 49 months after having undergone Insall's procedure. Outcome measures included reports of redislocations, complications, patient-reported outcome scores (Kujala, Tegner activity scale) and subjective assessment. No statistically significant improvements (p < 0.05) in patient-reported outcome measures were noted. Sixteen patients (35%) had poor to fair results using the Kujala score. Subjective assessment revealed that 12 patients (27%) were dissatisfied with the outcome of their surgery and would not undergo the same procedure. Ten patients (22%) had suffered from redislocation at the latest follow-up. In 4 cases (9%), intra-articular knee hematoma occurred which required arthroscopic intervention. The overall mid-term outcome of the present study shows low patient satisfaction. Non-anatomic realignment for recurrent patellar dislocation does not adequately prevent redislocation.

Galeazzi's modified technique for recurrent patella dislocation in skeletally immature patients

BACKGROUND

A large number of surgical techniques have been proposed for the treatment of recurrent patellar dislocation in adolescents, one of the most famous being Galeazzi's semitendinosus tenodesis as modified by Baker. The aim of this study was to verify the mid-term results of this technique, the effectiveness of restoring the patellofemoral congruency, by both static and dynamic computed tomography (CT), and to determine whether the preoperative type of patellofemoral relationship affects the results.

METHODS

The study included 14 patients (16 knees), with a mean age of 11.6 years, Tanner stage ≤3, with at least two to three episodes of patellar dislocation. The patients underwent surgery using Baker's modification of Galeazzi's technique. All 14 patients were evaluated preoperatively and at least 4 years afterward by static and dynamic CT. Clinical evaluation at follow-up was performed using the criteria described by Crosby and Insall.

RESULTS

Clinical results at follow-up were excellent in 62.5% and good in 37.5%. As preoperative evaluation showed a high patella in 7 out of 16 knees, two groups were considered: A, high patella; B, not high patella. The data obtained with static CT show that the patella reached a satisfactory congruence in all knees. The data obtained with dynamic CT showed different results between group A and B. A preoperative high patella remains high with quadriceps contraction and again shows the change of tilt and subluxation. In group B, the data obtained with dynamic CT are comparable with those obtained with static CT.

CONCLUSIONS

This technique produces good mid-term clinical results. However, the dynamic CT showed that in those patients with high patellas, semitendinosus tenodesis alone is not enough to stabilize the patella.

The role of the medial ligamentous structures on patellar tracking during knee flexion

PURPOSE

The influence of the medial patellar ligamentous structures on patellar tracking has rarely been studied. Thus the main purpose of this cadaveric biomechanical study was to determine the influence of the medial patellofemoral (MPFL), medial patellomeniscal (MPML) and medial patellotibial (MPTL) ligaments on the three-dimensional patellar tracking during knee flexion. This study was conducted using a validated cadaveric optoelectronic protocol for analysis of patellar kinematics.

METHODS

For each cadaveric knee study, four successive acquisitions were performed; first was studied patellar tracking in healthy knees, then the junction between MPFL and vastus medialis obliquus (VMO) was sectioned, the MPFL was released at its patellar attachment and finally was released the insertion of the MPML and MPTL.

RESULTS

In this study, the MPFL accounts for 50-60% of the medial stabilization forces of the lateral patellar shift during patellar engagement in the femoral trochlea. This work confirm and clarify the role of the MPFL as the primary stabilizer of the patella during the initial 30° of knee flexion. Moreover, this study shows no significant results regarding the stabilizing action of the VMO on the patella during knee flexion.

CONCLUSION

This in vitro study, conducted with an experimental protocol previously validated in the literature, helps quantify the actions of the MPFL, the VMO, and the MPML/MPTL respectively, and identify areas of joint motion where these structures have the most significant influence. This confirms the importance of reconstruction in the treatment of chronic patellar instability. During its reconstruction, care should be taken to adjust the MPFL balance during the initial 20°-30° of flexion.

Reconstruction of medial patellofemoral ligament for chronic patellar instability

BACKGROUND

Disruption of the capsule, medial patellar retinaculum, and/or vastus medialis obliqus has been associated with recurrent patellar instability. Biomechanical studies have shown that the medial patellofemoral ligament (MPFL) is the main restraint against lateral patella displacement and reconstruction of the MPFL has become an accepted surgical technique to restore patellofemoral stability in patients having recurrent patellar dislocation. We report a prospective series of patients of chronic patellar instability treated by reconstruction of medial patellofemoral ligament.

MATERIALS AND METHODS

Twelve patients (15 knees) with recurrent dislocation of patella, were operated between January 2006 and December 2008. All patients had generalised ligament laxity with none had severe grade of patella alta or trochlear dysplasia. The MPFL was reconstructed with doubled semitendinosus tendon. Patients were followed up with subjective criteria, patellar inclination angle, and Kujala score.

RESULTS

The mean duration of followup after the operative procedures was an average of 42 months (range 24-60 months) 10 knees showed excellent results, 3 knees gave good results, and 2 knees had a fair result. The average patellar inclination angle decreased from 34.3° to 18.6°. The average preoperative Kujala functional score was 44.8 and the average postoperative score was 91.9.

CONCLUSION

MPFL reconstruction using the semitendinosus tendon gives good results in patients with chronic patellar instability without predisposing factors like severe patella alta and high-grade trochlear dysplasia, and for revision cases.

Recurrent dislocation of the patella accompanying hypotrochlea of the femur and malalignment of the patella

This case report describes a rare case of recurrent dislocation of the patella which was accompanied with trochlear dysplasia and malalignment of the patella in a 15-year-old girl. She complained of hemoarthrosis and recurrent patellar dislocation in the early knee flexion phase. Plain radiography and computed tomography (CT) showed patellar malalignment (quadriceps angle 20°) and severe dysplasia of the trochlea of the femur (sulcus angle 170°). Surgery was performed, consisting of trochleoplasty in addition to proximal and distal realignment. Trochleoplasty was undertaken using a modified Dejour technique. After surgery, the patient complained of joint contracture. Arthroscopic release of fibrous tissue relieved symptoms and obtained normal range of motion without patellar dislocation. Postoperative radiography and CT demonstrated improvement of the quadriceps angle (10°) and sulcus angle (140°).

[Treatment of patellar instability in children and adolescents]

To address recurrent patellar instability in children and young adolescents a variety of therapeutic options exist either as non-operative or operative treatment. Recent options, such as reconstruction of the medial patellofemoral ligament have evoked a new focus of attention on this topic. The intention of this article is to present diverse therapeutic options and to evaluate them by reference to the current literature.

Technical failure of medial patellofemoral ligament reconstruction

In patients with chronic patellofemoral instability who have normal alignment and deficient proximal medial restraints, medial patellofemoral ligament (MPFL) reconstruction is a good option to treat patellar instability. However, medial subluxation, medial patellofemoral articular overload, and recurrent lateral instability are possible when the graft is positioned non-anatomically. The clinical presentation of MPFL femoral tunnel malpositioning has not been highlighted in the literature. We have had 5 patients referred to us after a malpositioned femoral MPFL graft led to disabling symptoms and a need for revision surgery. This report highlights the effects of a malpositioned graft and describes strategies to identify the anatomic MPFL insertion during surgery.

Dual tunnel medial patellofemoral ligament reconstruction for patients with patellar dislocation using a semitendinosus tendon autograft

The purpose of this study was to describe a safer and more anatomical technique of MPFL reconstruction and to report the short-term results. The subjects included 20 patients with patellar dislocation with a mean age of 23. The operation was performed using a double-looped autogenous semitendinosus tendon graft. Two small bone tunnels were made at the medial edge of the patella, mimicking the wide patellar insertion of the MPFL and a bone tunnel was made at the femoral insertion site. The free ends of the graft attached to the patella and the loop end was fixed to the femoral side. Five patients were available for follow-up interviews by telephone and the remaining 15 were directly examined by physical examination and radiographic evaluation at 2 years or longer postoperatively. The average follow-up period was 30 months. Re-dislocation or patellar fracture was not seen in any patients. The average Kujala's score was 96 with a range from 84 to 100. Six patients were classified as excellent and 14 as good, according to the Crosby and Insall grading system. Radiographically, narrowing of the patellofemoral joint space was observed in 2 cases with previous osteochondral fracture out of those who were directly examined. The dual tunnel MPFL reconstruction produces favorable results in subjective and functional assessment of outcome without complications.

Patellar instability: combined treatment with Goldthwait technique and arthroscopic lateral release

Patellar instability is a frequent cause of knee pain in childhood and adolescence. Treatment is usually conservative especially after a single episode of dislocation, although in cases of recurrence the surgical option needs to be evaluated. The techniques proposed involve only soft tissues in order to preserve the skeletal maturation. This study evaluates the long-term results on 20 knees in 19 adolescents affected by patellar instability treated with the distal realignment procedure involving medial transfer of the lateral hemi-patellar tendon according to Goldthwait technique, preceded by arthroscopy to perform lateral release. The results were analysed with the Cox grading system and showed 11 excellent cases, 6 good cases, 2 fair cases and 1 poor case. Similar findings were obtained with the Bray score.

Acute patellar dislocation in adolescents: operative versus nonoperative treatment

PURPOSE

The purpose of this prospective non-randomised study was to compare the efficacy of two opposed methods, operative and conservative. Our hypothesis was that if the method was selected correctly, on an individual basis, the results should be approximately equal.

METHODS

The study included 37 adolescents aged between 12 and 16 years, with a mean follow up of 6.1 years. The presence of a significant loose body, confirmed by precise imaging, was the key for selecting operative or arthroscopic treatment. In both groups of patients, we evaluated functional knee scores and the incidence of residual patellofemoral disorders.

RESULTS

We confirmed our hypothesis using the t-test to compare functional results and a test for comparison of proportions for incidence of residual disorders. There was no statistically significant difference (p=0.091) between operatively and conservatively treated groups with regard to functional results. The same statistical outcome emerged when comparing incidences of re-dislocation (p=0.854), or other major patellar instabilities (p=0.856), between the groups.

CONCLUSIONS

The results obtained should not promote a non-operative method on the basis of lower risk, but do support an individual approach based on precise diagnosis and defined criteria.

A systematised MRI approach to evaluating the patellofemoral joint

Knee pain in young patients is a common indication for knee MRI. Many static and dynamic internal derangements of the patellofemoral joint in these patients lead to various secondary MRI findings. This article focuses on how to systematically approach, detect, and emphasize the importance of these findings in the diagnosis of patellofemoral tracking and impingement syndromes with relevant case examples.

Superolateral Hoffa's fat pad edema: association with patellofemoral maltracking and impingement

OBJECTIVE

Nonelderly patients presenting with knee pain often have patellofemoral maltracking or impingement abnormalities. There is a relative paucity of literature on the incidence and significance of impingement-related edema of the superolateral aspect of Hoffa's (infrapatellar) fat pad in these cases. Our study was designed to systematically evaluate the correlation of superolateral Hoffa's fat pad edema with various anatomic parameters of trochlear morphology and patellar alignment.

MATERIALS AND METHODS

We evaluated 50 knee MRI examinations in 47 patients for the presence of edema in superolateral Hoffa's fat pad and associated anatomic abnormalities of the patellofemoral joint.

RESULTS

Of the 50 examinations, 25 (50%) showed superolateral Hoffa's fat pad edema, and statistically significant differences were seen between those with and without edema with respect to sex (6/22 men vs 19/28 women) and patellar tendon patellar-length ratio (1.3 ± 0.16 and 1.1 ± 0.12 for those with and without edema, respectively).

CONCLUSION

The findings in our study suggest that edema in superolateral Hoffa's fat pad may be an important indicator of underlying patellofemoral maltracking or impingement in younger, symptomatic patients.

MR imaging of patellar instability: injury patterns and assessment of risk factors

First-time patellar dislocation typically occurs with twisting knee motions, during which the medial ligamentous stabilizers rupture, and the patella strikes against the lateral femoral condyle. The typical injury pattern is a tear of the medial patellofemoral ligament (MPFL) and bone bruises of the patella and the lateral femoral condyle. Additionally, complex injuries to bone, cartilage, and ligaments may occur. The ensuing loss of medial restraint favors future patellar dislocations, especially if additional risk factors are present. Recurrent patellar dislocations usually occur in individuals with anatomic variants of the patellar stabilizers, such as trochlear dysplasia, patella alta, and lateralization of the tibial tuberosity. Magnetic resonance (MR) imaging is reliable in identifying risk factors for chronic patellar instability and in assessing knee joint damage associated with patellar dislocation. MR imaging can thus provide important information for individually tailored treatment. Patients with primary patellar dislocation without severe internal derangement who lack major risk factors can be treated conservatively. Patients with pronounced ligamentous tears or large osteochondral lesions require prompt surgery. In addition, surgical correction of anatomic variants will help reduce the potential for chronic instability. The most common procedures, in addition to MPFL reconstruction, include trochleoplasty, medialization of the tibial tuberosity, and medial capsular plication. For comprehensive assessment of patellar dislocation, a radiologist should be able to identify typical injury patterns, know standard methods to assess risk factors for patellar instability, and be familiar with surgical options.

Measurement characteristics of a force-displacement curve for chronic patellar instability

OBJECTIVE

The clinical diagnosis of patellar instability is subjective, depending on the patient's apprehension. We hypothesized that a subjective diagnosis could be supported by a numerical evaluation of the slope, or compliance, of the early phase of a force-displacement curve.

DESIGN

Cross-sectional control group comparison.

SETTING

A university-based sports clinic.

PARTICIPANTS

Healthy volunteers (n = 21; 16-40 years old) and patients (n = 21; 15-34 years old) who had a clearly definable diagnosis of unilateral dislocation, followed by chronic anterior knee pain, and positive apprehension signs for more than 6 months, without patella alta or abnormal limb alignment.

INTERVENTION

Lateral displacement and reactive forces were measured with a Patella Stability Tester.

MAIN OUTCOME MEASURES

Sensitivity in detecting injured knees was defined, with the 95% confidence interval of healthy subjects determined as the normal range.

RESULTS

Compliance at 5 mm in displacement showed the highest reproducibility (plot difference of 4.7%) and the highest sensitivity (95%). Among injured knees, compliance was significantly correlated with the activity-related symptoms of the Kujala score (correlation coefficient, -0.61; P = 0.004). Compliance at 5 mm of displacement showed the highest sensitivity (95%) and significant correlation with the activity-related symptoms of the Kujala score among injured knees (coefficient of determination, 0.37; P = 0.004).

CONCLUSIONS

It is a novel finding that early compliance at 5 mm of displacement showed a correlation with the subjective diagnosis and symptoms.

Anatomy of lateral patellar instability: trochlear dysplasia and tibial tubercle-trochlear groove distance is more pronounced in women who dislocate the patella

BACKGROUND

A trend toward young women being at greatest risk for primary and recurrent dislocation of the patella is evident in the current literature. However, a causative factor is missing, and differences in the anatomical risk factors between men and women are less defined.

PURPOSE

To identify differences between the sexes in the anatomy of lateral patellar instability.

STUDY DESIGN

Case control study; Level of evidence, 3.

METHODS

Knee magnetic resonance images were collected from 100 patients treated for lateral patellar instability. Images were obtained from 157 patients without patellar instability who served as controls. Using 2-way analyses of variance, the influence of patellar dislocation, gender, and their interaction were analyzed with regard to sulcus angle, trochlear depth, trochlear asymmetry, patellar height, and the tibial tubercle-trochlear groove (TT-TG) distance. Mechanisms of injury of first-time dislocations were divided into high-risk, low-risk, and no-risk pivoting activities and direct hits.

RESULTS

For all response variables, a significant effect was observed for the incidence of patellar dislocation (all P < .01). In addition, sulcus angle, trochlear asymmetry, and trochlear depth depended significantly on gender (all P < .01) but patellar height did not (P = .13). A significant interaction between patellar dislocation and gender was observed for the TT-TG distance (P = .02). The mean difference in TT-TG distance between study and control groups was 4.1 mm for women (P < .01) and 1.6 mm for men (P = .05). Low-risk and no-risk pivoting injuries were most common in women, whereas first-time dislocations in men occurred mostly during high-risk pivoting activities (P < .01).

CONCLUSION

The data from this study indicate that trochlear dysplasia and the TT-TG distance is more prominent in women who dislocate the patella. Both factors might contribute to an increased risk of lateral patellar instability in the female patient as illustrated by the fact that dislocations occurred most often during low-risk or no-risk pivoting activities in women.

Outcome of surgery for recurrent patellar dislocation based on the distance of the tibial tuberosity to the trochlear groove

We evaluated the outcome in a series of patients with recurrent patellar dislocation who had either medial transfer of the tibial tuberosity and lateral release or an isolated lateral release as the primary treatment. The decision to use one or other procedure was based on a pre-operative distance between the tibial tuberosity to the trochlear groove (TTTG) of less than 10 mm to include the tibial tuberosity transfer in addition to the lateral release.

Between April 2002 and December 2006, 49 patients (63 knees) underwent one of these procedures. A total of 35 patients (46 knees) was evaluated at a mean of 38 months (13 to 71) post-operatively. Medial transfer of the tibial tuberosity was performed in 33 knees and isolated lateral release in the remaining 13. Evaluation included the International Knee Documentation Committee (IKDC), the Kujala and the Short-form 36 scores. From the tibial tuberosity group 23 knees also underwent radiological examination at follow-up.

There were further episodes of patellar dislocation in six of the 46 knees available for review. Further dislocation was noted in five of 33 knees (15.2%) in the tibial tuberosity transfer group and in one of 13 knees (7.7%) in the lateral release group. The mean subjective IKDC score was 80.4 (sd 11.6), the mean Kujala score 88 (sd 8.2) and the mean objective IKDC score was 79% normal and 21% nearly normal. The mean post-operative TTTG distance in the tibial tuberosity transfer group was 8.9 mm (3.2 to 15.7) compared with the mean pre-operative value of 16.8 mm (12.2 to 24.4).

Incidence of acute traumatic patellar dislocation among active-duty United States military service members

BACKGROUND

Although some studies have reported an increased incidence of patellar dislocations within active populations, few studies have reported incidence rates and examined risk factors for this injury.

PURPOSE

To examine the incidence of patellar dislocation injuries and the influence of demographic and occupational risk factors associated with injury among active-duty United States (US) service members between 1998 and 2007.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Using the Defense Medical Surveillance System, a search was performed for International Classification of Disease, 9th Revision (ICD-9) code 836.3 among all US service members on active duty during the study period. Multivariable Poisson regression analysis was used to estimate the rate of patellar dislocation per 1000 person-years at risk to injury. Incidence rates (IRs) and incidence rate ratios (IRRs) for patellar dislocation along with 95% confidence intervals (CIs) were estimated by gender, age, race, branch of military service, and rank while controlling for the other variables in the model.

RESULTS

There were a total of 9299 individuals with documented patellar dislocation injuries among a population at risk of 13 443 448 person-years. The IR was 0.69 per 1000 person-years at risk. Women were 61% more likely (IRR, 1.61; 95% CI, 1.53-1.69) to sustain a patellar dislocation injury than men. Rates were highest in the youngest age group and decreased with increasing age. Service members aged <20 years were 84% more likely (IRR, 1.84; 95% CI, 1.61-2.10) to sustain a patellar dislocation injury as service members aged ≥40 years. Differences were also noted by race, service, and rank.

CONCLUSION

The incidence of patellar dislocation injuries among US service members was an order of magnitude greater than that previously reported in civilian population studies. Gender, age, race, rank, and branch of military service are important risk factors related to the incidence of patellar dislocation injuries in this population.

First-time patellar dislocation with resultant habitual dislocation two years later, which was not demonstrated on plain X-rays halfway: a case report

We present an instructive case of habitual left patellar dislocation in which the patella had appeared odd due to lateral tilt relative to contralateral side, but had been radiologically confirmed to be on the trochlea at 1 year prior to the referral. An 11-year-old girl presented to our hospital 2 years after the left patella had dislocated with a 'giving way' when cutting to the left. Our physical and radiological examinations confirmed that the left patella was laterally tilted in the patellar groove with the knee in extension but was dislocated in flexion beyond 45°. In spite of these findings, she had been untreated at the previous hospital since all plain X-rays, including a skyline patellar view, had failed to demonstrate the dislocation. Consequently, in addition to reconstruction of medial patellofemoral ligament, she had to undergo a lateral retinacular release, which might have been unnecessary if treated earlier. This case illustrates that first-time patellar dislocation can gradually lead to habitual dislocation subsequently, and that cautious physical examinations in regard to patella tracking are essential since radiological examinations do not always reveal the pathophysiology of patellar instability.

Magnetic resonance imaging characteristics of the medial patellofemoral ligament lesion in acute lateral patellar dislocations considering trochlear dysplasia, patella alta, and tibial tuberosity-trochlear groove distance

PURPOSE

The objective of this study was to analyze the injury patterns of the medial patellofemoral ligament (MPFL) in acute lateral patellar dislocations (LPDs) considering the anatomically relevant factors of patellar instability.

METHODS

Knee magnetic resonance images were collected from 73 patients within 7 weeks after LPD, and the injury patterns of the MPFL were evaluated for trochlear dysplasia, for patellar height, and for the tibial tuberosity-trochlear groove (TT-TG) distance.

RESULTS

Injury to the MPFL was found in 98.6% of the patients (72 of 73) after the acute LPD, with a complete tear in 51.4% (37 of 72), most frequently localized at the femoral attachment site, and a partial tear in 48.6% (35 of 72). Injury to the femoral origin (Fem), to the midsubstance (Mid), and to the patellar insertion (Pat) of the MPFL was found in 50.0% (36 of 72), 13.9% (10 of 72), and 13.9% (10 of 72), respectively. More than 1 site of injury was found in 22.2% (16 of 72), most frequently as a combined injury at the femoral origin and at the patellar insertion sites (Pat+Fem) (13 of 16). The study population, as well as the Pat, Fem, and Pat+Fem subgroups, showed significantly different values of trochlear dysplasia and patellar height when compared with the control group, whereas the data of the Mid group were not significantly different. In addition, injury at the patellar insertion (Pat) was accompanied by a significantly increased TT-TG distance when compared not only with the control group but also with the Fem, Mid, and Pat+Fem groups.

CONCLUSIONS

The data from our study indicate that patterns of MPFL injury depend on trochlear dysplasia, patellar height, and TT-TG distance. They show a new aspect in the complex interplay between active, passive, and static stabilizers of the patellofemoral joint.

LEVEL OF EVIDENCE

Level IV, diagnostic case-control study.

Anatomical confirmation of the use of radiographic landmarks in medial patellofemoral ligament reconstruction

BACKGROUND

A recent study has described radiographic landmarks for femoral insertion of the medial patellofemoral ligament. Clinical relevance and application of these landmarks for surgical reconstruction have yet to be determined.

HYPOTHESIS

Radiographic landmarks can be used to accurately determine the femoral insertion of the medial patellofemoral ligament in a percutaneous fluoroscopically guided surgical technique.

STUDY DESIGN

Descriptive laboratory study.

METHODS

The femoral insertion of the medial patellofemoral ligament was estimated using fluoroscopy in 8 fresh-frozen human cadaveric knees. The knees were dissected and the true anatomical medial patellofemoral ligament femoral insertion was identified. Radiographic markers were placed on both the estimated and anatomical medial patellofemoral ligament and a repeat lateral radiograph was performed. Using imaging software, the distance between the true anatomical insertion and the fluoroscopically determined insertion was calculated. Results All 8 points determined by fluoroscopically guided pin placement averaged less than 4 mm from the anatomical insertion. The radiographic landmark method consistently placed the origin on average 2.5 mm anterior and 0.6 mm distal to the anatomical insertion.

CONCLUSION

Radiographic landmarks determined by fluoroscopy can be used to accurately reproduce the femoral insertion of the medial patellofemoral ligament in ligament reconstruction.

CLINICAL RELEVANCE

Confirming the use of radiographic landmarks to determine the medial patellofemoral ligament femoral insertion may help to increase accuracy and precision in ligament reconstruction and minimize surgical dissection.

MPFL reconstruction for PF instability. The soft (tissue) approach

Historically, anatomic factors have been identified that increase one's risk for episodic lateral patella dislocations. A surgical treatment algorithm has been proposed which utilizes these risk factors. This algorithm depends primarily on realignment of the bony architect. Increasingly, the soft tissue retinacular restraints have been shown to be important as an anatomic factor critical for patellofemoral stability; in particular, the medial patellofemoral ligament (MPFL) has been recognized as the essential stabilizer against lateral patella displacement. Current indications for MPFL reconstructions will be reviewed. The frequency of reconstructing the MPFL alone versus combining it with other realignment schemes in my last 30 patients will be presented.

Gymnastics injuries and imaging in children

Injuries of children participating in gymnastics are seen less often than in more popular sports. Patterns of injury are predictable based upon sex, age and level of intensity of training and competition. More injuries are seen in girls than in boys, and the great majority of early adolescents who compete have wrist pain. Some otherwise quiescent congenital spine anomalies may be uncovered by the stress of gymnastics maneuvers and present with low back pain. In addition to diagnosis of injuries, imaging can be used to guide analgesic and anti-inflammatory therapy in some injured athletes. Parents whose children wish to participate in gymnastics should understand that fewer injuries occur in the child enjoying recreational gymnastics than in competing gymnasts. More gymnastics injuries are found in very competitive athletes training at higher levels.

The 3-in-1 procedure for recurrent dislocation of the patella in skeletally immature children and adolescents

BACKGROUND

Recurrent patellar dislocations are common injuries in children and adolescents. The subjective and functional results of soft tissue surgical management in a population that was skeletally immature at the time of surgery have not been reported.

HYPOTHESIS

The 3-in-1 procedure is an effective treatment for recurrent patellar dislocation in skeletally immature patients.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-five skeletally immature patients (age at operation, 13.5 +/- 3.8 years) who were practicing sports and suffering from recurrent unilateral patellar dislocation were included in the study and followed until skeletal maturation. Clinical evaluation included the modified Cincinnati rating system and the Kujala score, anthropometry, plain radiography, and isokinetic dynamometry.

RESULTS

The average follow-up was 3.8 years (range, 2.5-6 years). The mean modified Cincinnati score increased from 51.7 +/- 12.6 preoperatively to 94.3 +/- 10.8 (P < .02), while the mean Kujala scores increased from 52.4 +/- 12.7 preoperatively to 93.8 +/- 14.2 (P < .02). The Insall-Salvati index remained essentially unchanged, being 1.04 +/- 0.2 preoperatively and 1.02 +/- 0.3 at latest follow-up. Significant differences were found between the operated and the contralateral limb in the various isokinetic strength variables at all angular velocities measured at the latest follow-up (.05 < P < .0042).

CONCLUSION

The 3-in-1 procedure is a safe, reliable management option for recurrent patellar dislocation in skeletally immature patients. Side-to-side differences in isokinetic strength and in anthropometric indices persist despite subjective success of the procedure.

The effects of timing of pediatric knee ligament surgery on short-term academic performance in school-aged athletes

BACKGROUND

Orthopaedic injuries negatively affect the academic lives of children.

HYPOTHESIS

The timing of anterior cruciate ligament (ACL) and medial patellofemoral ligament (MPFL) reconstructions affects academic performance in school-aged athletes.

STUDY DESIGN

Cohort study; Level of evidence, 2. Methods Records of patients < or = 18 years old who underwent ACL or MPFL reconstructions from 2001-2007 were reviewed retrospectively. Subjects had been administered a unique questionnaire to evaluate school life in the immediate postoperative period as well as International Knee Documentation Committee (IDKC), Lysholm, and Kujala knee-specific questionnaires. Patients were in 1 of 3 study cohorts: group A (surgery during school year), group B (surgery during school holiday), and group C (surgery during summer break).

RESULTS

There were 62 subjects (53 ACL and 12 MPFL reconstructions). A higher proportion of patients in group A required being driven to school (88.5%) than groups B (63.6%) or C (64.7%) (P < .05). A lower proportion of patients in group A returned to school immediately after surgery (3.8%) than groups B (36.4%) or C (88.2%) (P < .005). Among children who had never failed a test before surgery, a higher proportion of patients in group A failed a test (36.4%) after return to school than groups B (0%) or C (0%) (P < .05). Patients in group C had higher mean Likert scores (4.5) than groups A (3.8) or B (3.7) (P = .05) in response to the question "my grades suffered in my classes." Delay in surgery was negatively correlated with IKDC, Lysholm, and Kujala questionnaire scores (P < .05).

CONCLUSION

In school-aged athletes with ligamentous knee injuries receiving operative treatment, surgery on a school day causes more academic difficulties than surgery during a holiday or summer break. Academic benefits of delaying surgery during the school year must be weighed against potentially worse outcomes encountered with prolonged surgical delay.

The structural properties of the lateral retinaculum and capsular complex of the knee

Although lateral retinacular releases are not uncommon, there is very little scientific knowledge about the properties of these tissues, on which to base a rationale for the surgery. We hypothesised that we could identify specific tissue bands and measure their structural properties. Eight fresh-frozen knees were dissected, and the lateral soft tissues prepared into three distinct structures: a broad tissue band linking the iliotibial band (ITB) to the patella, and two capsular ligaments: patellofemoral and patellomeniscal. These were individually tensile tested to failure by gripping the patella in a vice jaw and the soft tissues in a freezing clamp. Results: the ITB–patellar band was strongest, at a mean of 582 N, and stiffest, at 97 N/mm. The patellofemoral ligament failed at 172 N with 16 N/mm stiffness; the patellomeniscal ligament failed at 85 N, with 13 N/mm stiffness. These structural properties suggest that most of the load in-vivo is transmitted to the patella by the transverse fibres that originate from the ITB.

Conservative versus surgical treatment for repair of the medial patellofemoral ligament in acute dislocations of the patella

PURPOSE

The objective of this study was to analyze and compare the results obtained after 2 types of treatment, surgical and conservative, for acute patellar dislocations.

METHODS

We divided 33 patients with acute patellar dislocations into 2 groups. One group with 16 patients underwent conservative treatment (immobilization and subsequent physiotherapy), and the other group with 17 patients underwent surgical treatment. A radiographic examination was performed in the evaluation of the patients to verify predisposing factors for patellofemoral instability, and the Kujala questionnaire was applied with the intention of analyzing the improvement of pain and quality of life. The chi(2) test, t test, and Fisher test were used in the statistical evaluation. A significance level of P < .05 was adopted.

RESULTS

The groups were considered parametric in relation to age and sex. The conservative treatment group exhibited a higher number of recurrent dislocations (8 patients) than the surgical treatment group, which did not have any relapses. In addition, the surgical treatment group obtained a better mean score on the Kujala test (92) than the conservative treatment group (69).

CONCLUSIONS

We conclude that surgical treatment afforded better results. There were no recurrences in the surgical treatment group, but there were 8 recurrences in the conservative treatment group. The mean Kujala score was 92 in the surgical treatment group and 69 in the conservative treatment group.

LEVEL OF EVIDENCE

Level II, lesser-quality therapeutic randomized controlled trial.