Radiographic landmarks for femoral tunnel placement in medial patellofemoral ligament reconstruction

BACKGROUND

Reconstruction of the medial patellofemoral ligament has recently become popular for restoring patellofemoral stability. Femoral insertion site anatomy of the medial patellofemoral ligament has been described. This anatomical insertion has been inferred to be the isometric point in medial patellofemoral ligament reconstruction, but data about radiographic landmarks for a postoperative or intraoperative control are missing.

PURPOSE

To determine the radiographic landmarks for control of postoperative and intraoperative femoral medial patellofemoral ligament insertion.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Eight fresh-frozen human knees were dissected, and the medial patellofemoral ligament was exposed. After identification of the femoral medial patellofemoral ligament insertion site, the insertion center was marked with a lead ball of 2-mm diameter. Straight lateral radiographs were taken, and posterior-anterior as well as proximal-distal position were evaluated.

RESULTS

Six of 8 insertion points were anterior to a line representing an extension of the posterior cortex, 1 point was touching this line, and 1 point was posterior to it. All points were situated distal to the posterior origin of the medial femoral condyle and proximal to the most posterior point of the Blumensaat line.

CONCLUSION

A reproducible anatomical and radiographic point, 1 mm anterior to the posterior cortex extension line, 2.5 mm distal to the posterior origin of the medial femoral condyle, and proximal to the level of the posterior point of the Blumensaat line on a lateral radiograph with both posterior condyles projected in the same plane, shows the mean femoral medial patellofemoral ligament center.

CLINICAL RELEVANCE

This radiographic point may be useful both intraoperatively and postoperatively.

Osteotomies in patello-femoral instabilities

Patellar instability is defined by clinical and radiologic criteria. The surgical treatment is aimed at restoring the congruence of the patellofemoral articulation and correcting extensor mechanism malalignment, to prevent recurrence of dislocation. The standard soft-tissue procedures are lateral release and vastus medialis advancement and medial patello femoral ligament plasty. Bony procedures are frequently performed in addition to soft-tissue surgery, to realign the extensor mechanism by means of tibial tubercle medialization, or to correct the patellar index in patella alta. In a smaller number of patients, the trochlea may be reshaped, by elevating the lateral trochlear facet or by lowering the floor of the sulcus. The morphologic abnormalities encountered are studied and quantified in the light of preoperative investigations (conventional radiographs and computed tomography), and addressed at surgery using the technique or techniques most appropriate for the management of the individual patient's pattern.

First-time traumatic patellar dislocation: a systematic review

Acute patellar dislocations can result in patellar instability, pain, recurrent dislocations, decreased level of sporting activity, and patellofemoral arthritis. The initial management of a first-time traumatic patellar dislocation is controversial with no evidence-based consensus to guide decision making. Most first-time traumatic patellar dislocations have been traditionally treated nonoperatively; however, there has been a recent trend in initial surgical management. We performed a systematic review of Level I-IV studies to make evidence-based medicine recommendations on how a clinician should approach the diagnosis and treatment of a first-time traumatic dislocation. More specifically we answer the primary question of when initial treatment should consist of operative versus closed management. Based on the review of 70 articles looking at study design, mean followup, subjective and validated outcome measures, redislocation rates, and long-term symptoms, we recommend initial nonoperative management of a first-time traumatic dislocation except in several specific circumstances. These include the presence of an osteochondral fracture, substantial disruption of the medial patellar stabilizers, a laterally subluxated patella with normal alignment of the contralateral knee, or a second dislocation, or in patients not improving with appropriate rehabilitation.

Current concepts of lateral patella dislocation

Surgical treatment of patellar dislocations, acute and chronic, has evolved significantly over the past decade with the advance of biomechanical knowledge of patellofemoral restraints and injury patterns identified by physical examination and improved imaging techniques. There continues to be no consensus on treatment parameters. Despite the presence of predisposing factors, such as dysplasia or generalized hyperlaxity, medial retinacular injury associated with primary (first-time) patellar dislocations represents a ligament injury, which may result in residual laxity of the injured structure. This residual laxity is defined objectively by an increase in passive lateral excursion of the patella. Repair or reconstructive procedures to restore this medial constraint is considered paramount in any procedure to stabilize the patella against subsequent dislocations. How best to accomplish this continues to be a matter of debate. The establishment of a medial check-rein by either repairing or reconstructing the MPFL is the procedure of choice for stabilizing a kneecap after first-time dislocation, largely because the literature to date does not provide clear guidelines about when more extensive surgery is indicated. Whether or not all first-time dislocators have improved outcome after surgical repair remains speculative, however. Improved outcome would involve both the elimination of recurrent instability episodes and continued satisfactory function of this patella in activities-of-daily-living and sporting activities. These outcomes have not been studied critically in operative versus nonoperative treatment of first-time patellar dislocation. For the first-time dislocator, most investigators would agree that an arthroscopy should be performed if intra-articular chondral damage is suspected. Nonoperative management of first-time patellar dislocations continues to be the preferred practice pattern in the United States. If surgical management is elected, because of individual characteristics of the injury pattern or the patient's lifestyle, it is important to inspect the MPFL along its length and repair any or all ligamentous disruptions. If the ligament is avulsed from the medial epicondyle, reattachment to bone is necessary to restore passive restraint to lateral patella motion. MRI may be useful in order to identify the location and degree of medial soft tissue injury preoperatively. The establishment of a medial check-rein by either repairing or reconstructing the MPFL is a necessary component of all surgical procedures performed to correct objective lateral instability of the patella. The addition of a LRR should be additive to this procedure only when it facilitates other procedures to recenter the patella or when objective lateral tilt by physical examination measurements is present. A practical approach to surgery after patellar dislocation is the minimal amount of surgery necessary to re-establish objective constraints of the patella. Correcting dysplastic factors, in particular tibial tubercle transfers and trochleoplasties, are best reserved if more minimal surgery has failed. This failure is defined as continued functional instability of the kneecap.

The anatomy and reconstruction of the medial patellofemoral ligament

INTRODUCTION

Reconstruction of the MPFL for recurrent and acute lateral dislocation of the patella is becoming more accepted. This study aimed to further define the medial patellofemoral ligament (MPFL) anatomy and to describe the most suitable sites for graft attachment when reconstructing the MPFL.

MATERIALS AND METHODS

Anatomical dissection was performed on 25 embalmed knee specimens. Four separate specimens were used to assess graft fixation points. Sites were tested for isometricity from 0 to 120 degrees of knee flexion. Length patterns were considered isometric if there was less than 5 mm of length change throughout range of motion.

RESULTS

The MPFL attaches from the posterior part of the medial epicondyle, to the superomedial patella, the under-surface of vastus medialis, and the quadriceps tendon. Optimal attachment points for an MPFL graft were the superior patella and the femoral attachment points of the MPFL (just distal to the adductor tubercle) and points posterior and inferior to this.

CONCLUSION

We have defined the anatomy and kinematics of the MPFL with reconstruction of this ligament in mind.

Clinical and radiological outcome of medial patellofemoral ligament reconstruction with a semitendinosus autograft for patella instability

BACKGROUND

Recurrent patellar instability is a common problem after dislocation. The medial patellofemoral ligament (MPFL) contributes 40-80% of the total medial restraining forces. This study assessed the clinical and radiological outcome after a follow-up of 4 years after linear MPFL reconstruction using an ipsilateral Semitendinosus tendon autograft.

STUDY DESIGN AND METHODS

15 knees in 12 patients were examined with a mean of 47 months after linear reconstruction of the MPFL at a mean age of 30 years. 3 knees underwent previous surgery. 3 patients had mild trochlear dysplasia grade I or II, according to the classification of Dejour. If preoperative tibial tuberosity-trochlear groove distance (TTTG) was more than 15 mm, patients underwent additional medialisation of the tibial tuberosity (n=8) creating a similar postoperative situation for all patients. All patients were available for a postoperative evaluation, which consisted of a subjective questionnaire, the Kujala score, and the recording of potential patellar redislocation and apprehension. Patellar height and tilt was measured on plain radiographs. Postoperative CT scans were performed in patients with an additional tibial tuberosity-transfer.

RESULTS

Postoperatively, one patient reported on recurrent bilateral redislocation. Physical examination however revealed no findings. Three knees presented with persistent patellar apprehension. Thirteen knees had improved subjectively after surgery. The mean Kujala score improved significantly from 55.0 to 85.7 points. The patellar tilt decreased significantly from 11.3 degrees to 9.2 degrees. Four knees had patella alta preoperatively, but only two at the latest follow-up visit. Previous surgery or additional trochlear dysplasia had no influence on the clinical outcome.

CONCLUSION

MPFL reconstruction improves clinical symptoms, reduces the patellar tilt substantially, and may correct patella alta. Additional mild trochlear dysplasia did not compromise the outcome; however, this fact needs further attention in a larger study group.

Outcomes After Isolated Medial Patellofemoral Ligament Reconstruction for the Treatment of Recurrent Lateral Patellar Dislocations: A Systematic Review and Meta-analysis

BACKGROUND

A patellar dislocation is a common knee injury in the young, athletic patient population. Recent trends indicate that the use of long-term nonoperative treatment is decreasing, and surgical intervention is more commonly recommended for those patients who fail initial nonoperative management with recurrent patellar dislocations. Medial patellofemoral ligament (MPFL) reconstruction has become increasingly utilized in this regard.

PURPOSE

To evaluate outcomes, particularly return to sports and its relationship to postoperative instability, of isolated MPFL reconstruction for the treatment of recurrent patellar dislocations.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A review of the current literature was performed using the terms "medial patellofemoral ligament reconstruction" and "MPFL reconstruction" in the electronic search engines PubMed and EBSCOhost (CINAHL, MEDLINE, SPORTDiscus) on July 29, 2015, yielding 1113 abstracts for review. At the conclusion of the search, 14 articles met the inclusion criteria and were included in this review of the literature. Means were calculated for population size, age, follow-up time, and postoperative Tegner scores. Pooled estimates were calculated for postoperative Kujala scores, return to play, total risk of postoperative instability, risk of positive apprehension sign, and risk of reoperation.

RESULTS

The mean patient age associated with MPFL reconstruction was 24.4 years, with a mean postoperative Tegner score of 5.7. The pooled estimated mean postoperative Kujala score was 85.8 (95% CI, 81.6-90.0), with 84.1% (95% CI, 71.1%-97.1%) of patients returning to sports after surgery. The pooled total risk of recurrent instability after surgery was 1.2% (95% CI, 0.3%-2.1%), with a positive apprehension sign risk of 3.6% (95% CI, 0%-7.2%) and a reoperation risk of 3.1% (95% CI, 1.1%-5.0%).

CONCLUSION

A high percentage of young patients return to sports after isolated MPFL reconstruction for chronic patellar instability, with short-term results demonstrating a low incidence of recurrent instability, postoperative apprehension, and reoperations.

Medial patellofemoral ligament reconstruction in patients with lateral patellar instability and trochlear dysplasia

BACKGROUND

Reconstruction of the medial patellofemoral ligament has been proven to restore stability in patients with lateral patellar instability. No study to date has examined the results in a patient population with the predisposing factor of femoral trochlear dysplasia.

HYPOTHESIS

Reconstruction of the medial patellofemoral ligament restores stability and provides pain relief in patients who have lateral patellar instability in association with trochlear dysplasia.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Thirty-four patients with chronic patellar instability and trochlear dysplasia were treated with medial patellofemoral ligament reconstruction using an adductor tendon autograft, bone-quadriceps tendon autograft, or bone-patellar tendon allograft. All patients were evaluated preoperatively and postoperatively with Kujala, Lysholm, and Tegner scores at a minimum of 24 months.

RESULTS

Thirty-four patients were followed for a mean of 66.5 months (range, 24-130 months) after surgery. Kujala scores improved from 53.3 to 90.7, Lysholm scores improved from 52.4 to 92.1, and Tegner activity scores improved from 3.1 to 5.1. All improvements were highly statistically significant (P < .001). No statistical difference was found between the postoperative Lysholm, Kujala, and Tegner scores and the degree of dysplasia, graft type, or degree of symptoms. There were 85.3% and 91.1% good and excellent results based on Kujala and Lysholm scores, respectively. No recurrent dislocations have occurred.

CONCLUSION

Medial patellofemoral ligament reconstruction provides excellent long-term pain relief and functional return in patients with patellar instability and femoral trochlear dysplasia. In addition, reconstruction prevents recurrent dislocation, despite the diminished bony constraint of a dysplastic trochlea.

Trochleaplasty for recurrent patellar dislocation in association with trochlear dysplasia. A 4- to 14-year follow-up study

We investigated the clinical and radiological outcome of trochleaplasty for recurrent patellar dislocation in association with trochlear dysplasia in 38 consecutive patients (45 knees) with a mean follow-up of 8.3 years (4 to 14). None had recurrence of dislocation after trochleaplasty. Post-operatively, patellofemoral pain, present pre-operatively in only 35 knees, became worse in 15 (33.4%), remained unchanged in four (8.8%) and improved in 22 (49%). Four knees which had no pain pre-operatively (8.8%) continued to have no pain. A total of 33 knees were available for radiological assessment. Post-operatively, all but two knees (93.9%) had correction of trochlear dysplasia radiologically but degenerative changes of the patellofemoral joint developed in 30% (10) of the knees. We conclude that recurrent patellar dislocation associated with trochlear dysplasia can be treated successfully by trochleaplasty, but the impact on patellofemoral pain and the development of patellofemoral osteoarthritis is less predictable. Overall, subjective patient satisfaction with restored patellofemoral stability after trochleaplasty appeared to outweigh its possible sequelae.

Current concepts review: the medial patellofemoral ligament

Awareness of the medial patellofemoral ligament has increased markedly over the past decade. Previously, this structure, which was delineated in anatomical studies, had been little recognized and underestimated with regard to its importance in stabilizing the patella. The goal of this review of the medial patellofemoral ligament is to develop a current understanding of how this ligament functions in patellofemoral stability and to review the current treatment options for medial patellofemoral ligament disruption.

A long-term follow-up study after medial patellofemoral ligament reconstruction using the transferred semitendinosus tendon for patellar dislocation

The management of patellar dislocation syndrome has traditionally been difficult. There are no golden standard methods for patellar dislocations probably due to the many etiologies. However, it is known that medial patellofemoral ligament (MPFL) is damaged when the patella is dislocated. The purpose of this study is to examine whether our method of MPFL reconstruction is useful for the treatment of dislocated patellae and unstable patellae. Forty-six knees (43 patients) of 68 knees (65 patients) that were operated on using our surgical procedure for MPFL reconstruction with the advancement of the vastus medialis or the MPFL reconstruction with Insall's procedure were followed up for at least 5 years. The patient age ranged from 6 to 43 years. These knees consisted of six habitual dislocation patellae, twenty-six recurrent dislocation patellae, ten traumatic dislocation patellae, and four unstable patellae. The patients were evaluated pre-operatively and more than three times post-operatively at 6, 12, 36, 60, or 120 months. No patient experienced patellar dislocation after surgery. Their post-operative Kujala's scores were significantly improved. On conventional X-ray and on stress X-ray evaluations, the mean values for congruence angle, tilting angle, lateral shift ratio, medial stress shift ratio, and lateral stress shift ratio at the final follow-up (60 or 120 months) were demonstrated to be within the normal range. We conclude that our MPFL reconstruction method with the advancement of the vastus medialis or with Insall's procedure might be recommended for the treatment of habitual, recurrent, and indeed any other type of patellar dislocation, as well as for unstable patellae.

Operative treatment of primary patellar dislocation does not improve medium-term outcome: A 7-year follow-up report and risk analysis of 127 randomized patients

BACKGROUND

The best treatment for primary patellar dislocation has been the subject of debate. Surgery has been recommended for all patients or for special subgroups to improve outcome. We have previously reported similar 2-year results after closed or open treatment. This report concerns 127 patients who were re-evaluated by questionnaire at least 5 years after the primary onset.

PATIENTS AND METHODS

At baseline, the patients were randomized regarding closed treatment (57) or individually adjusted proximal realignment operation (70). All patients were re-evaluated after a mean follow-up of 7 (6-9) years.

RESULTS

The outcomes were similar: the patient's own overall opinion was excellent or good after closed treatment in 81% of cases and after operative treatment in 67%. Mean Kujala and Hughston VAS knee scores were 90 and 94, respectively, after closed treatment and 88 and 89 after operative treatment. The proportions of stable patellae were 30% and 36% for closed treatment and operative treatment, respectively. In a multivariate risk analysis, there was a correlation between a Kujala score of less than 90 and female sex (OR: 3.5; 95% CI: 1.4-9.0), loose bodies on radiographs (4.1; 1.2-15), and also an initial history of contralateral patellar instability (3.6; 0.9-15). There were 2 risk factors for recurrent instability: initial contralateral instability (4.9; 0.9-28) and young age (0.9; 0.8-1.0/year). Girls with open tibial apophysis had the worst prognosis for instability (88%; 95% CI: 77-98).

INTERPRETATION

We do not recommend proximal realignment surgery for treatment of primary dislocation of the patella.

Acute traumatic primary patellar dislocation: long-term results comparing conservative and surgical treatment

OBJECTIVE

This report evaluates the subjective, clinical, and functional long-term results comparing surgical and conservative treatment in patients with a primary traumatic patellar dislocation.

DESIGN AND SETTING

This retrospective clinical study focuses on patients with primary acute traumatic patellar dislocation. Patients with radiologic signs indicative of a predisposition for recurrent patellar instability were excluded from this study.

PATIENTS

A total of 126 patients were examined a mean of 8.1 years after initial treatment of their primary patellar dislocation.

INTERVENTIONS AND MAIN OUTCOME MEASUREMENTS

Patients were retrospectively divided into groups with conservative therapy (n = 63), diagnostic arthroscopy only (n = 20), immediate surgical reconstruction of the parapatellar ligament complex (n = 37), and refixation of osteochondral fragments (n = 6). Redislocation and resurgery rate, activity level, and subjective, clinical, and functional results were evaluated in these patients, and the outcomes in these groups were compared.

RESULTS

In the long term, functional results (as expressed in the Lysholm score) were excellent or good in 85% of the patients, and good subjective results were reported by 71%, but follow-up revealed a recurrence rate of 26% in the total study population. The high activity level before the initial trauma could not be completely regained after treatment. There was no significant difference between the surgically and conservatively treated groups in the redislocation and reoperation rates, level of activity, or functional and subjective outcomes.

CONCLUSIONS

Even with a focus on acute traumatic etiology and when factors predisposing to recurrent instability are largely excluded, the redislocation rate after treatment of acute patellar dislocation is still high, despite good clinical and subjective results. Conservative management seems to be the treatment of choice in patients with acute patellar dislocation, provided that the generally accepted indications for surgery, such as evidence of osteochondral fragments and major defects of the parapatellar ligament complex, are given due consideration.

Trochleaplasty for patellar instability due to trochlear dysplasia: A minimum 2-year clinical and radiological follow-up of 19 knees

BACKGROUND

Recurrent patellar dislocation may be associated with trochlear dysplasia. Trochleaplasty is a surgical procedure which strives to deepen the trochlear groove. We evaluated the clinical and radiological effect of trochleaplasty after a minimum follow-up of 2 years.

PATIENTS AND METHODS

We examined 19 knees in 16 patients at a mean of 3 years after trochleaplasty. Postoperatively, a subjective questionnaire, a Kujala score, and tests for potential patellar redislocation and apprehension were evaluated. On radiographs we evaluated the preoperative and postoperative crossing sign, trochlear depth, trochlear bump, and patellar height. On CT scans, the pre- and postoperative tibial tuberosity to trochlear groove distance (TTTG) and the patellar inclination angle were measured.

RESULTS

16 of 19 knees improved subjectively. The Kujala score increased from 56 to 80 points at the latest follow-up. None of the patients sustained a redislocation. 5 patients had medial parapatellar tenderness, including 4 with persistent apprehension. Radiological signs of trochlear dysplasia were corrected.

INTERPRETATION

Patellofemoral instability with underlying trochlear dysplasia can be treated successfully by trochleaplasty.

Long-term follow-up and knee osteoarthritis change after medial patellofemoral ligament reconstruction for recurrent patellar dislocation

BACKGROUND

Proximal or distal realignment procedures have long been selected as treatment for recurrent patellar dislocation, but associated knee osteoarthritis has been a substantial problem that leads to poor results. A new approach, medial patellofemoral ligament reconstruction, has recently started, but there have been no reports on the long-term follow-up.

HYPOTHESIS

Anatomical medial patellofemoral ligament reconstruction can lead to satisfactory long-term outcome and a low association rate of knee osteoarthritis.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty-four knees from 22 patients who underwent medial patellofemoral ligament reconstruction for recurrent patellar dislocation were reviewed at a mean follow-up of 11.9 years (range, 8.5-17.2 years). A lateral release was done on 14 of 24 knees. The clinical/physical outcome and the association of knee osteoarthritis were investigated. Patellofemoral and femorotibial osteoarthritis on the radiographs was evaluated using the Crosby/Insall and the Kellgren/Lawrence grading systems.

RESULTS

According to the Crosby/Insall criteria, 11 knees (46%) were classified as excellent, 10 (42%) as good, 3 (12%) as fair/poor, and none as worse at follow-up. Further lateral subluxation or dislocation occurred in only 2 knees. The mean Kujala score improved significantly from 63.2 points preoperatively to 94.2 points at follow-up (P < .0001). According to the Crosby/Insall grading system, patellofemoral osteoarthritis was none to mild in 23 of the 24 knees and moderate in 1 knee, pre-operatively. At the final follow-up, 21 knees were none to mild, and 3 knees were moderate. There were only 2 knees that had definite progression from none to mild to a moderate grade.

CONCLUSION

The association of definite knee osteoarthritis in medial patellofemoral ligament reconstruction with or without lateral release was small in the long-term follow-up. The conclusion is that medial patellofemoral ligament reconstruction not only prevents further patellar dislocation but also shows no or only slight progression of knee osteoarthritis.

A simple technique for reconstruction of the medial patellofemoral ligament using a quadriceps tendon graft

Numerous surgical procedures have been described for the treatment of recurrent patellar dislocation. Studies have shown that the primary pathoanatomy associated with lateral patellar dislocation is injury to the medial patellofemoral ligament (MPFL), which is the major soft-tissue restraint to lateral patellar translation. Recently, various procedures have been described that address the medial ligamentous injury inherent to lateral patellar dislocation. We present a simple technique for MPFL reconstruction using a quadriceps tendon graft.

Hybrid medial patellofemoral ligament reconstruction using the semitendinous tendon for recurrent patellar dislocation: minimum 3 years' follow-up

PURPOSE

The purpose of this study was to evaluate the results of a new hybrid medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar dislocation.

METHODS

Hybrid MPFL reconstruction by use of the semitendinous tendon was performed in 12 knees with recurrent patellar dislocation. The results were evaluated at a minimum follow-up of 3 years (mean, 4.2 years).

RESULTS

According to the grading system of Insall et al., the results were classified as excellent in 8 knees (66%), good in 2 (17%), and fair in 2 (17%), with none being classified as poor. The mean Kujala score was 56.3 points (range, 29 to 82) preoperatively and 96.0 points (range, 84 to 100) at follow-up. There were no patients with recurrent dislocation and subluxation. No knees had a positive apprehension sign, and there were no postoperative complications.

CONCLUSIONS

At a midterm follow-up, hybrid MPFL reconstruction by use of the semitendinous tendon for recurrent patellar dislocation should be considered as an effective operation for cases without severe predisposing factors.

LEVEL OF EVIDENCE

Level IV, therapeutic case series, no or historical control group.

Modified Dejour trochleoplasty for severe dysplasia: operative technique and early clinical results

Instability of the patella occurs when it fails to track fully in the femoral groove during knee movement. The groove begins at the metaphysis of the distal femur and extends on its anterior surface inferiorly to the femoral notch. It is normally present at birth and the cartilaginous shape is similar to that of the adult. An abnormal trochlea may be shallow. In extreme cases it may be dome-shaped, where it is associated with recurrent subluxation or dislocation of the patella. In these cases it is logical to consider fashioning a groove as part of a realignment procedure. This study reports the operative technique and early clinical and radiological results of a consecutive case series of the first 15 patients (17 knees) who underwent a deepening trochleoplasty for severe dysplasia developed from that described by Dejour. The follow-up was for a minimum of 1 year (average 3 years, range 1 to 9 years). The boss height was reduced from an average of 7.5 mm (range 6 to 11 mm) to 0.7 mm (range -1 to 3 mm). Tracking became normal in 11 knees and had a slight J-shaped in six. Seven knees had mild residual apprehension. Seven patients were very satisfied, six were satisfied, and two were disappointed. The Kujala score improved from an average of 48 (range 13 to 75) to 75 (range 51 to 98) out of 100 (p<0.05). Three patients returned to full sports. Eight patients required further operations apart from the removal of metallic screws in 10 knees. Five of these were arthroscopic arthrolysis for stiffness at about 6 weeks post-operatively. Trochleoplasty for severe dysplasia of the femoral sulcus is a developing procedure. It requires careful attention to detail. For a rare condition the early results have been satisfactory with an acceptable level of complications.

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.

Anatomical double-bundle MPFL reconstruction with an aperture fixation

Since biomechanical studies have shown that the medial patellofemoral ligament (MPFL) is the main restraint against lateral patella displacement, reconstruction of the MPFL has become an accepted method of restoring patellofemoral stability and numerous techniques were described. Due to biomechanical examinations and clinical results, an anatomical double-bundle reconstruction of the "sail-like" MPFL is a reasonable method for achieving stability during complete extension and lower flexion degree. This method also serves to avoid rotation of the patella, providing immediate stability throughout the normal range of motion. However, until today, an aperture fixation technique at the patellar insertion with two bundles has not been described previously. This technique can provide an immediate stability to allow an early rehabilitation with full range of motion.

Lateral retinacular release: a survey of the International Patellofemoral Study Group

PURPOSE

The purpose of this investigation was to determine current views regarding lateral release among experienced knee surgeons with a specific interest in the patellofemoral joint.

TYPE OF STUDY

Scientific survey.

METHODS

A questionnaire was developed and mailed to all members of an international group with a specific interest in disorders of the patellofemoral joint. Frequencies and percentages of responses were calculated for each question to determine surgeon consensus. We measured agreement among responses using the kappa statistic. This provided an indication of consistency for each question as well as correlation among the responses to different questions.

RESULTS

The survey response rate was 60%. Isolated lateral release was estimated to account for only 1 to 5 surgical cases per respondent per year, or 2% of cases performed annually. In the setting of arthroscopy or exploration, 74% of respondents believed that lateral release calls for specific informed consent. Strong consensus was found that objective evidence is needed to justify lateral release, but agreement was poor as to what clinical evidence provides the most appropriate indication for the procedure.

CONCLUSIONS

Even among experienced knee surgeons with a special interest in diseases of the patellofemoral articulation, isolated lateral release is rarely performed. Strong consensus was found that isolated lateral release should not be undertaken without prior planning in the form of objective clinical indications and preoperative informed consent.

LEVEL OF EVIDENCE

Level V.

Surgical technique and rationale for medial patellofemoral ligament reconstruction for recurrent patellar dislocation

This article describes a medial patellofemoral ligament (MPFL) reconstruction procedure using an artificial ligament for recurrent patellar dislocation. The MPFL has been shown biomechanically to be the primary restraint among the medial patellar stabilizers. Although various predisposing factors are involved in lateral patellar dislocation, we believe that the MPFL, as a primary restraint, should undergo primary reconstruction for patellar dislocation. The results of MPFL reconstruction using a mesh-type artificial ligament and medial retinaculum slip coverage for recurrent patellar dislocation were as good as we had expected. In this article, we describe the detailed surgical technique and its rationale. We believe technique has also wide applications in MPFL reconstruction using autogenous tendons.

Complications associated with corrective surgery for patellar luxation in 109 dogs

OBJECTIVE

To review surgical techniques and postoperative complications associated with correction of patellar luxation in dogs.

STUDY DESIGN

Retrospective study.

ANIMALS

Dogs (n = 109) with patellar luxation (n = 131).

METHODS

Medical records of dogs that had corrective surgery for patellar luxation were reviewed. Signalment, history, grade and direction of patellar luxation, operative technique and clinical outcomes were retrieved.

RESULTS

Overall frequency of postoperative complications was 18%. Frequency of major (requiring revision surgery) complications was 13%. Frequency of patellar reluxation was 8%. Frequency of overall, major, and patellar reluxation complications was higher for dogs weighing > or =20 kg compared with those <20 kg. Frequency of overall and major complications was higher for dogs with higher grades of patellar luxation. Femoral trochlear sulcoplasty resulted in lower frequency of patellar reluxation. Tibial tuberosity transposition (TTT) resulted in lower frequency of major complications and patellar reluxation. Retinacular/capsular release resulted in higher frequency of major complications. Patient age, gender, medial versus lateral patellar luxation, left versus right hindlimb, capsular/retinacular imbrication, use of anti-rotational sutures, and whether stifle surgery had been performed previously did not significantly influence frequency of complications.

CONCLUSION

TTT and femoral trochlear sulcoplasty minimize the risk of postoperative patellar reluxation and major complications.

CLINICAL RELEVANCE

Information derived from this study can be used to estimate the likelihood of postoperative complications for canine patients undergoing corrective surgery for patellar luxation.

Clinical outcomes of medial patellofemoral ligament reconstruction in patients with an increased tibial tuberosity-trochlear groove distance

PURPOSE

Medial patellofemoral ligament (MPFL) reconstruction is performed to treat recurrent patellar dislocation (RPD). However, the effectiveness of MPFL reconstruction in patients with a severely lateralised tibial tuberosity remains unknown. In this study, the clinical outcomes of MPFL reconstruction in patients with an increased tibial tuberosity-trochlear groove (TT-TG) distance were examined.

METHODS

A total of thirty-four patients who underwent MPFL reconstruction for RPD were retrospectively examined. Nineteen patients with a TT-TG distance of >20 mm (increased TT-TG distance group) were compared with 15 patients with a TT-TG distance of <20 mm (control group). Clinical outcomes of MPFL reconstruction were evaluated by occurrence of re-dislocation, Crosby and Insall grading system, apprehension sign, and Kujala and Lysholm scores.

RESULTS

None of the patients reported re-dislocation. Apprehension sign remained in three patients in the increased TT-TG distance group and in one patient in the control group. According to the Crosby and Insall grading system, 9 patients (47%) were excellent, 9 (47%) were good, and 1 (5%) was fair to poor in the increased TT-TG distance group, while 6 (40%) were excellent and 9 (60%) were good in the control group. Kujala and Lysholm scores were significantly improved post-operatively in both groups. No significant correlations were observed between TT-TG distance and post-operative Kujala or Lysholm score.

CONCLUSION

Overall clinical outcomes of MPFL reconstruction were favourable even in patients with an increased TT-TG distance. TT-TG distance of >20 mm may not be an absolute indication for medialisation of the tibial tuberosity when performing MPFL reconstruction.

LEVEL OF EVIDENCE

Case-control study, Level III.

Risk of Redislocation After Primary Patellar Dislocation: A Clinical Prediction Model Based on Magnetic Resonance Imaging Variables

BACKGROUND

First-time lateral patellar dislocations have historically been treated with a nonoperative approach; a clinical tool to predict patients who are most likely to redislocate may have clinical utility.

PURPOSE

(1) To determine if there are discriminating factors present between patients who redislocated their patellas and those who did not after a first-time lateral patellar dislocation and (2) to use this information to develop a model that can predict the recurrence risk of lateral patellar dislocation in this population.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The study population included those with first-time lateral patellar dislocation, magnetic resonance imaging within 6 weeks, and 2-year minimum follow-up. Cohort A was from a prospective study with 2-year follow-up. Cohort B was a prospectively identified cohort with retrospective chart review. Follow-up was obtained clinically or via mail for patients without 2-year clinical follow-up.

RESULTS

Sixty-one patients (42%) out of 145 with primary lateral patellar dislocation had recurrent dislocation within 2 years. Stepwise logistic regression analysis demonstrated that skeletal immaturity (odds ratio, 4.05; 95% CI, 1.86-8.82; P = .0004), sulcus angle (odds ratio, 4.87; 95% CI, 2.01-11.80; P = .0005), and Insall-Salvati ratio (odds ratio, 3.0; 95% CI, 1.34-6.70; P = .0074) were significant predictors of redislocation. Receiver operator characteristic curves defined the cut points to be sulcus angle ≥154° and Insall-Salvati ratio ≥1.3. The probability of redislocation based on the presence of factors was 5.8% with no factors present and 22.7% with any 1 factor present, increasing to 78.5% if all 3 factors were present.

CONCLUSION

This model demonstrates a high risk of lateral patellar redislocation when a patient presents with skeletal immaturity as well as magnetic resonance measurements of sulcus angle ≥154° and patellar height as measured by Insall-Salvati ratio ≥1.3. A patient will have a low risk of lateral patellar redislocation with the inverse findings.