Current concepts of lateral patella dislocation

Varus distal femoral osteotomy in young adults with valgus knee

Background

Musculoskeletal disorders specially knee osteoarthritis are the most common causes of morbidity in old patients. Disturbance of the mechanical axis of the lower extremity is one of the most important causes in progression of knee osteoarthritis. The purpose of the present study was to analyze the surgical results of distal femoral varus osteotomy in patients with genu valgum.

Methods

In this study, after recording history and physical examination, appropriate radiographs were taken. We did varus distal femoral osteotomy by standard medial subvastus approach and 90-angle blade plate fixation then followed the patients clinically and radiographically.

Results

This study was done on 23 knees (16 patients) age 23.3 years (range, 17 to 41 years). The mean duration of following up was 16.3 months (range, 8 to 25 months). Based on paired T test, there were statistically significant difference between pre- and postoperative tibiofemoral and congruence angles (p < 0.001, t = 21.3 and p < 0.001, t = 10.1 respectively). Pearson correlation between the amount of tibiofemoral and congruence angle correction was also statistically significant (p = 0.02 and r = 0.46).

Conclusion

Distal femoral varus osteotomy with blade plate fixation can be a reliable procedure for the treatment of valgus knee deformity. In this procedure, with more tibiofemoral angle correction, more congruence angle correction can be achieved. Therefore, along with genu valgum correction, the patella should be stabilized simultaneously.

Extensor mechanism injuries in tibiofemoral dislocations

OBJECTIVE

The purpose of this study is to evaluate the incidence, location, and associated findings of extensor mechanism injuries in the setting of tibiofemoral knee dislocations.

METHODS

A retrospective search for patients with previous knee dislocation and MRI of the knee was made during a 5-year period. Images were evaluated for abnormalities commonly seen in patellar instability. Patellar and quadriceps tendon integrity were also evaluated.

RESULTS

A total of 14 patients were included in the study. Medial patellofemoral ligament injuries were identified in 10 patients (71%) with tibiofemoral dislocation. As in patients with previous patellar dislocation, medial patellofemoral ligament injuries commonly occurred at the femoral attachment of the ligament. Medial patellofemoral ligament injuries correlated well with vastus medialis oblique elevation. Patellar tendon injuries were less common identified in only 5 patients (36%).

CONCLUSIONS

Medial patellofemoral ligament injuries can be associated with tibiofemoral knee dislocations. In addition, patellar tendon injuries can also occur, although these are usually partial tears.

Treatment with and without initial stabilizing surgery for primary traumatic patellar dislocation. A prospective randomized study

BACKGROUND

There is no consensus about the management of acute primary traumatic patellar dislocation in young physically active adults. The objective of this study was to compare the clinical outcomes after treatment with and without initial stabilizing surgery for primary traumatic patellar dislocation in young adults.

METHODS

Forty young adults, thirty-seven men and three women with a median age of twenty years (range, nineteen to twenty-two years), who had an acute primary traumatic patellar dislocation were randomly allocated to be treated with initial surgical stabilization (eighteen patients, with each receiving one of two types of initial stabilizing procedures) or to be managed with an orthosis (twenty-two patients, including four who had osteochondral fragments removed arthroscopically). After a median of seven years, thirty-eight patients returned for a follow-up examination. Redislocations, subjective symptoms, and functional limitations were evaluated. Radiographs and magnetic resonance images were obtained at the time of randomization, and twenty-nine (76%) patients underwent magnetic resonance imaging at the time of final follow-up.

RESULTS

A hemarthrosis as well as injuries of the medial retinaculum and the medial patellofemoral ligament were found on magnetic resonance imaging in all patients at the time of randomization. During the follow-up period, six of the twenty-one nonoperatively treated patients and none of the seventeen patients treated with surgical stabilization had a redislocation (p = 0.02). Four nonoperatively treated patients and two patients treated with surgical stabilization reported painful patellar subluxation. The median Kujala scores were 91 points for the surgically treated patients and 90 points for the nonoperatively treated patients. Thirteen patients in the surgically treated group and fifteen in the nonoperatively treated group regained their former physical activity level. At the time of follow-up, a full-thickness patellofemoral articular cartilage lesion was detected on magnetic resonance imaging in eleven patients; the lesions were considered to be unrelated to the form of treatment.

CONCLUSIONS

In a study of young, mostly male adults with primary traumatic patellar dislocation, the rate of redislocation for those treated with surgical stabilization was significantly lower than the rate for those treated without surgical stabilization. However, no clear subjective benefits of initial stabilizing surgery were seen at the time of long-term follow-up.

Distal realignment and patellar autologous chondrocyte implantation: mid-term results in a selected population

The aim of this prospective observational study was to assess the 3-year clinical outcome of distal realignment and membrane-seeded autologous chondrocyte implantation (MACI) in selected patients with patellofemoral malalignment and large, isolated, patellar cartilage lesions. Twelve patients (14 knees; 6 females, 6 males; mean age 31 years) with Fulkerson type II patellofemoral malalignment (lateralized and tilted patella) and Outerbridge grade III-IV isolated patellar cartilage lesions were treated. All had tibial tuberosity and trochlear sulcus >20 mm on a preoperative CT scan and a cartilage defect >3 cm2. Patients with Outerbridge grade III-IV trochlear cartilage lesions, those with rheumatic, infective or neoplastic conditions, or ligament instability, diabetes or obesity and those aged >40 years were excluded. Follow-up was at 36 months. Patients were enrolled after diagnostic arthroscopy. Cartilage was harvested and sent for culture. After a mean period of 30 days (range 25-40) patients underwent transfer of the tibial tuberosity according to Fulkerson associated with a MACI procedure. Clinical assessment was performed with the Kujala, Lysholm, Tegner and Modified Cincinnati scores. The Patient Satisfaction Survey was administered at 36 months. Consistently improved knee function and activity levels were reflected by significantly increased Kujala, Lysholm, Tegner and Modified Cincinnati scores at 36 months. The significant clinical improvement support the value of associating distal realignment and autologous chondrocyte implantation in treating large, isolated, patellar cartilage lesions associated with patellofemoral malalignment.

Process for applying the international classification of functioning, disability and health model to a patient with patellar dislocation

BACKGROUND AND PURPOSE

The International Classification of Functioning, Disability and Health (ICF) has been proposed as a possible framework for organizing physical therapist practice. The purpose of this case report is to describe an evaluative and diagnostic process that is based on the ICF framework for a patient with a patellar dislocation.

CASE DESCRIPTION

The patient was a 23-year-old woman who sustained a right knee and patellofemoral joint injury, resulting in a sprain of the medial collateral ligament and a suspected sprain of the medial patellofemoral ligament. Evaluation at 4 weeks demonstrated a primary impairment of patellar instability associated with the primary activity limitation of limited walking distances. A plan of care to address impairments, activity limitations, and participation restrictions was developed, with modifications made on the basis of the patient's health condition and personal and environmental factors.

OUTCOMES

The patient attained all of her goals for therapy and was able to return to her normal activities and recreational pursuits without a recurrence of a patellar dislocation. Lower-Extremity Function Scale scores increased from 30 out of 80 to 76 out of 80 during the course of treatment.

DISCUSSION

The ICF model has been proposed as a framework for developing diagnostic classifications for rehabilitation professionals. The ICF model also should be assessed with regard to whether it provides a useful process for clinical decision making. The ICF model directs practitioners to address patients' problems at the level of the whole person, with modifications made on the basis of health conditions and personal and environmental factors.

The management of recurrent patellar dislocation

Acute and chronic trauma, chronic abnormal joint loading conditions, and hemarthroses have been implicated in the development of degenerative joint disease. Patellar instability with acute and recurrent patellar dislocation provides all of these ingredients. This article describes an approach to the treatment of recurrent patellar instability that considers the unique features and expectations of the patient rather than using a generic algorithm.

Sonographic evaluation of the injuries after traumatic patellar dislocation in adolescents

BACKGROUND

Traumatic patellar dislocation (TPD) may be associated with other injuries requiring additional treatment. The superficial localization of the knee extensor apparatus and knee articular cartilage make them accessible to sonographic evaluation (ultrasonography [USG]).

PURPOSE OF THE STUDY

Prospective analysis of the value of USG in TPD.

METHODS

In 21 patients, 22 knees were examined by USG after clinical and routine radiographic evaluations. Based on USG findings, operative or nonoperative treatment was done (15 and 7 cases, respectively).

RESULTS

In 17 knees, lesions of the medial patellofemoral ligament (MPFL) fibers were visible. In 16 knees, avulsion fractures of the patellar insertion of the MPFL were identified. Injuries of the femoral attachment of the MPFL or intramuscular hematoma of the vastus medialis obliquus (VMO) were present in 7 knees. Eleven osteochondral loose bodies and 1 nondisplaced osteochondral fracture were detected in 11 knees. Corresponding osteochondral lesions were localized in all cases. An osteochondral loose body that was identified by USG was confirmed intraoperatively or by computed tomographic scan in 91.6%, the osteochondral lesion localization in 81.8%, and avulsion fracture of the patellar attachment of the MPFL in 100% of knees. Overall, the USG findings were confirmed by these methods in 88.2% of knees.

CONCLUSIONS

Ultrasonography is highly efficient in determining the extent of injuries after TPD in adolescents. Ultrasonography allows visualization of loose bodies, localization of osteochondral lesions, and, using a dynamic modification, allows precise assessment of the functional status of the MPFL.

LEVEL OF EVIDENCE

II.

Acute patellar dislocation in children and adolescents: a randomized clinical trial

BACKGROUND

The treatment of acute patellar dislocation in children is controversial. Some investigators have advocated early repair of the medial structures, whereas others have treated this injury nonoperatively. The present report describes the long-term subjective and functional results of a randomized controlled trial of nonoperative and operative treatment of primary acute patellar dislocation in children less than sixteen years of age.

METHODS

The data were gathered prospectively on a cohort of seventy-four acute patellar dislocations in seventy-one patients (fifty-one girls and twenty boys) younger than sixteen years of age. Sixty-two patients (sixty-four knees) without large (>15 mm) intra-articular fragments were randomized to nonoperative treatment (twenty-eight knees) or operative treatment (thirty-six knees). Operative treatment consisted of direct repair of the damaged medial structures if the patella was dislocatable with the patient under anesthesia (twenty-nine knees) or lateral release alone if the patella was not dislocatable with the patient under anesthesia (seven knees). All but four patients who underwent operative treatment had a concomitant lateral release. The rehabilitation protocol was the same for both groups. The patients were seen at two years, and a telephone interview was conducted at a mean of six years and again at a mean of fourteen years. Fifty-eight patients (sixty-four knees; 94%) were reviewed at the time of the most recent follow-up.

RESULTS

At the time of the most recent follow-up, the subjective result was either good or excellent for 75% (twenty-one) of twenty-eight nonoperatively treated knees and 66% (twenty-one) of thirty-two operatively treated knees. The rates of recurrent dislocation in the two treatment groups were 71% (twenty of twenty-eight) and 67% (twenty-four of thirty-six), respectively. The first redislocation occurred within two years after the primary injury in twenty-three (52%) of the forty-four knees with recurrent dislocation. Instability of the contralateral patella was noted in thirty (48%) of the sixty-two patients. The only significant predictor for recurrence was a positive family history of patellar instability. The mode of treatment and the existence of osteochondral fractures had no clinical or significant influence on the subjective outcome, recurrent patellofemoral instability, function, or activity scores.

CONCLUSIONS

The long-term subjective and functional results after acute patellar dislocation are satisfactory in most patients. Initial operative repair of the medial structures combined with lateral release did not improve the long-term outcome, despite the very high rate of recurrent instability. A positive family history is a risk factor for recurrence and for contralateral patellofemoral instability. Routine repair of the torn medial stabilizing soft tissues is not advocated for the treatment of acute patellar dislocation in children and adolescents.

Patellar tendon shortening after treatment of patellar instability with a patellar tendon medialization procedure

Patellar instability is a multifactorial disorder. Patella alta is strongly associated with patellar instability. We hypothesize that procedures of the patellar tendon such as medialization may shorten the patellar tendon. In this retrospective study, 41 patients with patellar instability were treated operatively with a patellar tendon medialization procedure. Twenty-eight knees were treated using a modified Roux-Goldthwait method and 16 using a modified Elmslie-Trillat method. The patients were followed 2-7 years after the operation. Pre- and post-operative x-rays were analyzed with particular emphasis on patellar tendon length, patellofemoral congruence angle and osteoarthritis. The final clinical outcome was assessed using the Lysholm score and clinical examination. In both groups patients were generally satisfied with the result of the operation and there was no significant difference in Lysholm scores at follow-up. However, patellofemoral osteoarthritic changes increased in both groups compared with the pre-operative status. The patellar tendon length was reduced in both groups, but significantly, by 7%, in the Roux-Goldthwait group. We conclude that patellar tendon shortens after a Roux-Goldthwait procedure.

The ‘four-in-one’ procedure for habitual dislocation of the patella in children

We describe our experience with the ‘four-in-one’ procedure for habitual dislocation of the patella in five children (six knees). All the patients presented with severe generalised ligamentous laxity and aplasia of the trochlear groove. All had a lateral release, proximal ‘tube’ realignment of the patella, semitendinosus tenodesis and transfer of the patellar tendon. The mean age at the time of the operation was 6.1 years (4.9 to 6.9), and the patients were followed up for a mean of 54.5 months (31 to 66). The clinical results were evaluated using the Kujala score.

There has been no recurrence of dislocation. All the patients have returned to full activities and the parents and children were satisfied with the clinical results. The mean Kujala score was 95.3 (88 to 98). Two patients had marginal skin necrosis which healed after debridement and secondary closure. These early results in this small group have shown that the ‘four-in-one’ procedure is effective in the treatment of obligatory dislocation of the patella in children with severe ligamentous laxity and trochlear aplasia.

Arthroscopic findings at the time of patellar realignment surgery in adolescents

Articular cartilage injuries and loose bodies have been associated with patellar dislocations. At the time of patellar realignment surgery (PRS), direct intraarticular visualization of the structures of concern may be limited with the use of a small arthrotomy. Concomitant diagnostic arthroscopy can improve the identification of intraarticular abnormalities, both patellofemoral and nonpatellofemoral, because of the better field of view.

PURPOSE

This report details the findings from knee arthroscopy performed concomitantly with PRS in adolescents.

METHODS

All patients underwent knee arthroscopy and open PRS for patellar instability, performed by a single surgeon, during a 4-year period. Patient demographics, knee history, clinical examination, operative findings, and treatment details were collected on all patients.

RESULTS

: Thirty-eight patients (mean age, 14.9 years; 41 knees) were included in this analysis. Patellar osteochondral lesions were present in 30 knees (73%; mean size, 112 mm). Femoral lesions were documented in 11 knees (23%; mean size, 81 mm). Loose bodies were present in 6 knees (15%). In 8 patients (20%), an additional 11 nonpatellofemoral diagnoses were made at the time of arthroscopy: lateral tibiofemoral chondroses (n = 4), medial meniscal tear (n = 2), lateral meniscal tear (n = 2), discoid lateral meniscus (n = 1), partial anterior cruciate ligament tear (n = 1), and medial tibiofemoral chondrosis (n = 1). Because of these findings, 5 additional procedures were performed in 4 patients: partial lateral meniscectomy (n = 2), medial meniscal repair (n = 1), discoid meniscus saucerization (n = 1), and staged distal femoral valgus-correcting osteotomy (n = 1).

CONCLUSIONS

By performing concomitant knee arthroscopy at the time of PRS, we were able to identify significant tibiofemoral abnormality in 4 patients, which would have been missed with direct inspection by a limited arthrotomy at the patellofemoral joint. In addition, precise evaluation of the patellofemoral joint permits customization of the PRS and aids in establishing appropriate patient expectations postoperatively. We advocate diagnostic knee arthroscopy at the time of PRS in adolescents to identify all intraarticular abnormalities and to optimize discussions with the patient and the caregivers on the long-term prognosis of the knee.

SIGNIFICANCE

Arthroscopic inspection of the knee at the time of PRS permits identification of abnormality that is not routinely visual by using open arthrotomy. Twenty percent of patients had additional pathological findings; of these patients, 50% underwent an additional surgical procedure.

Assessment and management of chronic patellofemoral instability

Chronic patellofemoral instability can be a disabling condition. Management of patients with this condition has improved owing to our increased knowledge of the functional anatomy of the patellofemoral joint. Accurate assessment of the underlying pathology in the unstable joint enables the formulation of appropriate treatment. The surgical technique employed in patients for whom non-operative management has failed should address the diagnosed abnormality. We have reviewed the literature on the stabilising features of the patellofemoral joint, the recommended investigations and the appropriate forms of treatment.

Current Concepts on Anatomy and Biomechanics of Patellar Stability

This review describes anatomic features of the patellofemoral joint that relate to the stability and function of the joint. The role of the geometry of the articular surfaces, particularly the trochlear groove, it's depth and orientation, are described. The stabilizing actions of the medial and lateral retinaculae, that tether the patella from either side to guide it into the trochlear groove in the early phase of knee flexion, are related to the specific structures, the medial patellofemoral ligament, and the fibers originating from the ilio-tibial tract laterally. The quadriceps muscles have different orientations, and converge onto the patella not only from either side but also from posteriorly, thus pulling the patella onto the anterior aspect of the trochlea. Finally, these local factors are discussed in relation to overall limb alignment, which leads to the mechanical logic of more extensive surgical procedures such as femoral rotational osteotomy or tibial tuberosity medialization.

Tibial tuberosity transfer for episodic patellar dislocation

Numerous surgical techniques have been described to address episodic patellar dislocations. Some of them involve the soft tissues whereas others primarily address a bony correction. Four principal anatomic factors have been identified that increase the risk for episodic patellar dislocations: trochlear dysplasia, patella alta, patellar tilt, and an excessive tibial tubercle-trochlear groove distance. A treatment algorithm has been proposed to correct each of these factors. It includes the tibial tuberosity transfer, which is able to correct both a patella alta and an excessive tibial tubercle-trochlear groove distance. The tibial tuberosity can be transferred distally or medially or more frequently a combination of both. It will realign the extensor mechanism and increase patellofemoral stability. This procedure may be associated with a medial patellofemoral ligament reconstruction in case of excessive patellar tilt or rarely with a trochleoplasty for major abnormal patellar maltracking.

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.

Comparison of lateral release versus lateral release with medial soft-tissue realignment for the treatment of recurrent patellar instability: a systematic review

PURPOSE

The purpose of this report is to present a systematic review of the literature to compare surgical success of lateral retinacular release (LRR) or LRR with medial soft-tissue realignment (MR) for recurrent lateral patellar instability.

METHODS

We searched MEDLINE and PubMed databases for all English-language studies reporting surgical management of recurrent lateral patellar instability with LRR or with LRR and MR. Exclusion criteria included a minimum follow-up <2 years, mean age <18 years old, bony realignment procedures, surgical treatment of an initial patellar instability episode, or surgical treatment of patellofemoral pain without instability. Surgical failure was defined as an episode of patellar dislocation or subluxation during the postoperative period. Statistical analysis compared the failure rate of LRR versus combined LRR with MR by using a Fisher exact test and assessed for publication bias.

RESULTS

Fourteen studies met inclusion criteria. There were 247 knees with a minimum 2-year follow-up after LRR and 220 after LRR with MR. In the LRR patients, there were 56 cases (probability 0.227, odds 0.293) of recurrent lateral patellar instability, 26 of which were postoperative patellar dislocations. In the LRR with MR patients, there were 14 cases (probability 0.064, odds 0.068) of recurrent instability, 12 of which were dislocations. The frequency-weighted mean success with respect to instability in the LRR studies was 77.3% compared with 93.6% in the LRR with MR studies. The odds of subsequent instability after LRR were significantly greater than after LRR with MR with respect to any postoperative instability (P < .001), recurrent dislocation (P = .045), and recurrent subluxation (P < .001).

CONCLUSIONS

This systematic review found that isolated LRR yields significantly inferior long-term results with respect to symptoms of recurrent lateral patellar instability compared with LRR with MR.

LEVEL OF EVIDENCE

Level III, systematic review of level III and IV studies.

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.

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.

High-resolution MRI using a microscopy coil for the diagnosis of recurrent lateral patellar dislocation

PURPOSE

Magnetic resonance imaging (MRI) has been commonly used for the preoperative evaluation of recurrent lateral patellar dislocation (RLPD). The purpose of this study was to determine the usefulness of high-resolution MRI (HR-MRI) with a microscopy coil for diagnosing RLPD.

MATERIALS AND METHODS

The study group consisted of 15 patients with clinically diagnosed RLPD and 10 normal volunteers. All studies were performed on a 1.5-T MR system. First, conventional MRIs of the whole knee joint were obtained using the knee coil. Then HR-MRI scans using a microscopy coil in the medial aspect of the patella were obtained at the level of the superior pole of the patella, targeting the medial patellofemoral ligament (MPFL). The acquired HR-MRIs with RLPD were reviewed concerning the MPFL injury and the patellar injury.

RESULTS

The MPFL was distinguished as a separate ligament, and the layer structure of the patellar cartilage was visualized clearly in all volunteers. The MPFL injury was visualized in 12 cases (87%); it included discontinuity, thickening, and loosening. The patellar injury was visualized in 11 cases (73%), which included dissecans of the medial margin and cartilage injuries.

CONCLUSION

HR-MRI with a microscopy coil provides precise information of the MPFL and patellar cartilage injury for the diagnosis of RLPD.

MRI of osteochondral defects of the lateral femoral condyle: incidence and pattern of injury after transient lateral dislocation of the patella

OBJECTIVE

The typical bone bruise pattern involving the anterolateral femoral condyle and inferomedial patella after transient lateral dislocation of the patella is a well-described MRI finding. In our study, however, we sought to determine the incidence and location of lateral femoral condyle osteochondral injuries after transient lateral dislocation of the patella.

CONCLUSION

Osteochondral defects of the lateral femoral condyle are a common sequela after transient lateral patellar dislocation. A significant number of osteochondral injuries involve the midlateral weight-bearing portion of the lateral femoral condyle and are more posterior than would be expected after transient dislocation of the patella.

Treatment of recurrent patellar instability with a modification of the Roux-Goldthwait technique

Recurrent instability of the patella may be a significant disability in the childhood and adolescent population. Numerous surgical procedures to address this instability have been described, with variable outcome. This has led to considerable confusion in the literature as to how to treat patellofemoral problems in children. This study retrospectively reviews 30 knees in 20 patients with chronic recurrent patellar instability who were treated with a modified Roux-Goldthwait technique including the release of contracted lateral structures by a single surgeon over a 13-year period, with an average of 6.2 years follow-up. By Insall's criteria, 26 knees had an excellent result, 3 good result, and 1 fair result. Ten patients evaluated using a dynamometer showed that strength achieved in the operated leg was greater than 90% in 8 patients and greater than 80% in 2 patients. Here, we report upon a single operation to treat patellar instability performed in the pediatric population with consistently excellent results.

Arthroscopic medial retinacular repair after patellar dislocation with and without underlying trochlear dysplasia: a preliminary report

PURPOSE

This study was undertaken to evaluate the influence of underlying trochlear dysplasia (TD) on clinical outcomes of arthroscopic medial retinacular repair.

METHODS

Between January 2000 and October 2004, a total of 91 patients underwent arthroscopic medial retinacular repair. Inclusion criteria for this study included an arthroscopic medial retinacular repair, a follow-up time of 12 months, and trochlear grading based on axial computed tomography (CT) scans (n = 48). TD, if present, was graded as types A through D, and patients were separated into group I (no or low-grade type A TD) and group II (types B through D TD). Redislocation was recorded, and Tegner, Lysholm, and International Knee Documentation Committee (IKDC) scores were determined.

RESULTS

No or grade A TD was detected in 26 knees (group I), and TD of grade B or C was found in 22 knees (group II). Type D TD was not observed. At a follow-up time of 12 months, 4 redislocations had been noted, all belonging to group II. Neither the Tegner nor the Lysholm score reached preinjury levels, but in a comparison with preoperative status, we could find a significant increase in all scores in both groups. Group I reached a significantly better postoperative outcome than was attained by group II.

CONCLUSIONS

Arthroscopic repair of the medial retinaculum is an effective technique by which patellofemoral instability can be addressed when normal or nearly normal trochlear geometry is present. In patients with underlying TD, patellofemoral stability cannot be completely restored, and clinical results are less successful. Precise preoperative radiologic determination of trochlear geometry may help the clinician to predict short-term outcomes in patients with patellofemoral instability.

LEVEL OF EVIDENCE

Level III, retrospective comparative therapeutic study.

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.

Arthroscopic release of the vastus lateralis tendon for recurrent patellar dislocation

BACKGROUND

Arthroscopic release of the vastus lateralis tendon for treatment of recurrent patellar dislocation has been criticized on the grounds that it may weaken the quadriceps.

HYPOTHESIS

Quadriceps strength and outcome measures improve after arthroscopic release of the vastus lateralis tendon in patients with documented patellar dislocation.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty patients who had recurrent patellar dislocation underwent arthroscopic lateral retinacular release that included a complete release of the vastus lateralis tendon from the superior pole of the patella and were observed prospectively. Bilateral quadriceps strength was tested preoperatively and at follow-up with an isokinetic dynamometer. Patients also completed the International Knee Documentation Committee Subjective Knee Form and the Short Form-36 preoperatively and postoperatively.

RESULTS

Follow-up averaged 27 months (range, 24-43 months). There were no redislocations. Mean quadriceps strength improved by a mean of 28% (from 32.3 to 41.4 N x m). The mean quadriceps torque ratio (involved/uninvolved) improved significantly from a preoperative value of 63% (31/51 N x m) to 80% (42/52 N x m) at follow-up (P = .017). Fourteen patients (70%) increased quadriceps torque, and 6 patients (30%) decreased quadriceps torque. Only 1 patient failed to improve on International Knee Documentation Committee and Short Form-36 scores. The International Knee Documentation Committee scores improved from 45 points preoperatively to 76 points at follow-up (P = .001). The Short Form-36 physical component summary scores improved from 38 points preoperatively to 50 points at follow-up (P = .007), and the Short Form-36 physical functioning subscale scores improved from 53 points to 86 points (P = .015).

CONCLUSION

Arthroscopic release of the vastus lateralis tendon and lateral patellar retinaculum in patients with recurrent patellar dislocation can improve quadriceps strength and knee function.

In vitro investigation of the effect of medial patellofemoral ligament reconstruction and medial tibial tuberosity transfer on lateral patellar stability

PURPOSE

Two different operative techniques for stabilizing the patella against lateral displacement movement were investigated.

TYPE OF STUDY

In vitro experimental study.

METHODS

Five human cadaver knee specimens with a normal Q-angle were mounted in a kinematic knee simulator and investigated under simulated isokinetic extension motions. Patellar movement was measured while a 100-N laterally directed subluxation load was applied to the patella. Ligament loading of the medial patellofemoral ligament was measured using a strain gauge based buckle transducer inserted in the fibers of the ligament. The knee was evaluated in an intact physiologic state, as well as after medial transfer of the tibial tuberosity, and after the medial patellofemoral ligament was transected and reconstructed using a hamstring autograft.

RESULTS

A significant reduction in lateral displacement and ligament load was observed with the use of the hamstring autograft reconstruction compared with the medial transfer of the tibial tuberosity.

CONCLUSIONS

Medial transfer of the tibial tuberosity showed no significant relief of ligament loading and stabilizing effect on patellar movement, whereas reconstruction of the medial patellofemoral ligament showed a significant stabilizing effect on patellar movement.

CLINICAL RELEVANCE

In cadaver specimens, we evaluated the effect of tibial tubercle transfer and the patellofemoral ligament and found that reconstruction of the patellofemoral ligament alone was sufficient to restore stability in a cadaveric model. Additionally, we found that the flexion angle had little effect on the loading of the medial patellofemoral ligament autograft, which would support early mobilization of patients after surgery. We found that the graft was not unduly loaded.

Estudo prospectivo e comparativo entre o tratamento conservador e o cirúrgico (reparo do ligamento femoropatelar medial) nas luxações agudas de patela

Foram avaliados dois grupos de pacientes com o primeiro episódio de luxação aguda femoropatelar traumática e acompanhados prospectivamente em relação às recidivas e aos fatores predisponentes à luxação. No Grupo I, 17 pacientes com média de idade de 24,6 anos, sendo 11 do sexo feminino, foram submetidos ao reparo do ligamento femoropatelar medial com menos de um mês de trauma. O tempo médio de seguimento foi de 40,4 meses e o mínimo de 18 meses. Como resultados, não houve nenhuma recidiva da luxação,houve dois episódios de subluxação . Nove pacientes apresentavam fatores predisponentes à luxação. No Grupo II, 15 pacientes com média de idade de 26,8 anos, sendo oito do sexo feminino, foram submetidos ao tratamento conservador com média de 18,5 dias de imobilização. O tempo de seguimento médio foi de 35,7 meses e o mínimo de 11 meses. Oito joelhos tiveram recidiva da luxação, apenas dois joelhos foram considerados estáveis . Neste grupo, 14 pacientes apresentavam fatores predisponentes. Concluímos que o tratamento cirúrgico das luxações agudas femoropatelares traumáticas apresenta resultados superiores quanto à recidiva em relação ao tratamento conservador no período estudado. A presença de fatores predisponentes em nossa série de pacientes não influenciou as recidivas das luxações femoropatelares.

Anatomical analysis of the medial patellofemoral ligament of the knee, especially the femoral attachment

The purpose of this study was to investigate the anatomical morphology and measurement of the medial patellofemoral ligament (MPFL), especially the femoral attachment. A total of 20 knee specimens were dissected and the total length, width, thickness, inclination, as well as the attachment points of the MPFL were measured. The MPFL was well-developed in seven knees, moderate in ten knees and wispy in three knees. Total length of the MPFL was 58.8 +/- 4.7 mm. The width and thickness was 12.0 +/- 3.1 mm and 0.44 +/- 0.19 mm at the middle point. The long axis of the MPFL inclined at 15.9 +/- 5.6 degrees proximally. The center of the patellar attachment was located at 27 +/- 10% from the upper end of the patella in the longitudinal patellar height. The femoral attachment was superoposterior to the medial femoral epicondyle and just distal to the adductor tubercle. The center of the anterior edge of the femoral attachment was 9.5 +/- 1.8 mm proximally and 5.0 +/- 1.7 mm posteriorly from the center of the medial femoral epicondyle. The femoral attachment was located at 61 +/- 4% of anteroposterior length of the medial femoral condyle from the anterior edge.

Physical examination of the knee

Even with the rapid advancement in technology and medical imaging, there is still no substitute for the history and physical examination that can be obtained from a patient. With a well-performed history and physical, the majority of pathology can be determined prior to any expensive imaging or surgical procedures. The knee is one of the most commonly injured joints, and its function is critical to basic ambulation and participation in sports, work, and activities of daily living. This article reviews the key concepts to a complete evaluation of the knee and highlights aspects of the physical examination and radiographic imaging that best aid in diagnosing knee pathology.

The role of autologous chondrocyte implantation in the patellofemoral joint

In a prospective study to determine the clinical effectiveness of autologous chondrocyte implantation, 45 patients reached a minimum followup of 2 years (range, 2-7 years; average, 46.4 months) after treatment involving the patellofemoral articulation. There were 28 men (61%) and 17 women (39%) and the average age of the patients was 37.5 years (range, 15-55 years). The treatment groups included (I) isolated patella, n = 8; (II) isolated trochlea, n = 9; (III) patella plus trochlea, n = 4; (IV) weightbearing condyle plus patella n = 2; (V) weightbearing condyle plus trochlea, n = 2; and (VI) weightbearing condyle plus patella plus trochlea n = 20. The average surface area per patella (n = 34) was 4.86 cm2 and per trochlea (n = 34) it was 5.22 cm2. The average resurfacing per knee (n = 45) was 10.45 cm2. We showed a postoperative improvement in quality of life as measured by the Short Form-36; Western Ontario and McMaster University Score, Knee Society Score, modified Cincinnati Score, and a patient satisfaction survey. There were eight failures (18%) as a result of a patella or trochlea failure. Seventy-one percent of patients rated their outcomes as good or excellent, 22% rated outcome as fair, and 7% rated outcome as poor.

LEVEL OF EVIDENCE

Therapeutic Study, Level II-1 (prospective cohort study). See the Guidelines for Authors for a complete description of levels of evidence.

Anatomy and malalignment of the patellofemoral joint: its relation to patellofemoral arthrosis

Patellofemoral joint function involves a complex orchestration of a number of dynamic, static, and neuromuscular factors. I will discuss the components of patellofemoral anatomy and whether the presence of certain anatomic variables may increase the risk of patellofemoral arthrosis. The patellofemoral surgeon is faced with several clinical challenges: the semantics of the language used to discuss these problems, the correlation of clinical symptoms and radiographic imaging to help diagnose a problem, and surgical challenges in optimizing extensor mechanism function.

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

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

The effects of articular, retinacular, or muscular deficiencies on patellofemoral joint stability

Normal function of the patellofemoral joint is maintained by a complex interaction between soft tissues and articular surfaces. No quantitative data have been found on the relative contributions of these structures to patellar stability. Eight knees were studied using a materials testing machine to displace the patella 10 mm laterally and medially and measure the force required. Patellar stability was tested from 0° to 90° knee flexion with the quadriceps tensed to 175 N. Four conditions were examined: intact, vastus medialis obliquus relaxed, flat lateral condyle, and ruptured medial retinaculae. Abnormal trochlear geometry reduced the lateral stability by 70% at 30° flexion, while relaxation of vastus medialis obliquus caused a 30% reduction. Ruptured medial retinaculae had the largest effect at 0° flexion with 49% reduction. There was no effect on medial stability. There is a complex interaction between these structures, with their contributions to loss of lateral patellar stability varying with knee flexion.

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.

Bilateral recurrent discloation of the patella associated with below knee amputation: a case report

BACKGROUND

Recurrent dislocation of the patella in patients with below knee amputation is a known entity. Abnormally high-riding patella (patella alta) and medial patellofemoral ligament insufficiency in these patients predisposes them to patellar instability. The established treatment of this problem is surgical realignment.

CASE PRESENTATION

A 25 year old male patient with bilateral below knee amputation presented with bilateral recurrent dislocation of the patella while walking on knees on uneven ground. Clinical and radiographic studies showed patella alta. A simple shoe modification was used to treat this patient.

CONCLUSIONS

A simple shoe modification can be used to treat such a condition which is otherwise treated surgically.

Tratamento da luxação femoro-patelar aguda pelo reparo do ligamento femoro-patelar medial

Os autores avaliaram a evolução de 17 pacientes que tiveram luxação femoropatelar aguda e foram tratados pela sutura do ligamento femoropatelar medial. A sutura do ligamento foi feita por via artroscópica em 9 pacientes que apresentaram a lesão do ligamento próxima à patela. Nos oito pacientes restantes a lesão do ligamento femoropatelar ocorreu próxima ao epicôndilo femoral e foi tratada pela reinserção no epicôndilo femoral com âncoras. Os pacientes foram acompanhados por um tempo médio de 40 meses e não houve nenhuma recidiva da luxação femoropatelar durante este período.

Imaging of patellofemoral disorders

Anterior knee pain is a common symptom, which may have a large variety of causes including patellofemoral pathologies. Patellofemoral maltracking refers to dynamic abnormality of patellofemoral alignment and has been measured using plain film, computed tomography (CT) and magnetic resonance imaging (MRI) using static and kinematic techniques. Patellar dislocation is usually transient, but specific conventional radiographic and MRI features may provide evidence of prior acute or chronic dislocation. In addition, chondromalacia patellae, osteochondritis dissecans, patellofemoral osteoarthritis, excessive lateral pressure syndrome, and bipartite patella have all been implicated in causing patellofemoral pain. The imaging and clinical features of these processes are reviewed, highlighting the specific diagnostic features of each condition.

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.