Medial patellofemoral ligament avulsion injury at the patella: classification and clinical outcome

Patellar Dislocation: Workup and Decision-Making

Acute patellar dislocation (PD) is usually a problem of adolescents and young adults. In most cases, it is a sports-related injury. It is the result of an indirect force on the knee joint, which leads to valgus and external rotation of the tibia relative to the femur. PD is unlikely to occur on a knee with normal patellofemoral joint (PFJ) anatomy. Acute PD consists of an acute injury of the ligamentous medial patellar stabilizers in the background of factors predisposing to patellar instability. These factors are classified into three groups. The first group refers to the integrity of the ligamentous medial patellar restraints, particularly, the medial patellofemoral ligament (MPFL). The second group refers to an abnormal PFJ anatomy, which renders the patella inherently unstable inside the trochlea. The third group refers to the overall axial and torsional profile of the lower limb and to systemic factors, such as ligament laxity and neuromuscular coordination of movement. PD at a younger age is associated with an increased number and severity of patellar instability predisposing factors and lower stress to dislocate the patella. Acute primary PD is usually treated conservatively, while surgical treatment is reserved for recurrent PD. The aim of treatment is to restore the stability and function of the PFJ and to reduce the risk of patellar redislocation. Surgical procedures to treat patellar instability are classified into non-anatomic and anatomic procedures. Non-anatomic procedures are extensor mechanism realignment techniques that aim to center the patella into the trochlear groove. Anatomic procedures aim to restore the PFJ anatomy (ruptured ligaments, osteochondral fractures), which has been severed after the first incident of PD. Anatomic procedures, especially MPFL reconstruction, are more effective in preventing recurrent PD, compared with non-anatomic techniques. Theoretically, all factors that affect PFJ stability should be evaluated and, if possible, addressed. This is practically impossible. Considering that the MPFL ruptures in almost all PDs, MPFL reconstruction is the primary procedure, which is currently selected by most surgeons as a first-line treatment for patients with recurrent PD. Restoration of the axial and torsional alignment of the lower limbs is also increasingly implemented by surgeons. Non-anatomic surgical techniques, such as tibial-tuberosity osteotomy, are used as an adjunct to anatomic procedures. In the presence of multiple PFJ instability factors, acute MPFL reconstruction may be the treatment of choice for acute primary PD as well. Skeletal immaturity of the patient precludes osseous procedures to avoid premature physis closure and subsequent limb deformity. Unfortunately, restoration of the patient's previous activity level or participation in more strenuous sports is questionable and not easy to predict. In the case of competitive athletes, PD may prevent participation in elite levels of sports.

A 20-Year Retrospective Study of Children and Adolescents Treated by the Three-in-One Procedure for Patellar Realignment

BACKGROUND

Patellar instability is the most common disorder of the knee during childhood and adolescence. Surgical treatment significantly reduces the rate of redislocation, but the underlying pathologies and pattern of instability may affect the results. We aimed to report the clinical and functional outcomes of the three-in-one procedure for patellar realignment in a cohort of skeletally immature patients with or without syndromes and various patterns of chronic patellar instability.

METHODS

We retrospectively investigated 126 skeletally immature patients (168 knees) affected by idiopathic or syndromic patellar instability, who underwent patella realignment through a three-in-one procedure. We classified the instability according to the score proposed by Parikh and Lykissas.

RESULTS

Patellar dislocation was idiopathic in 71 patients (94 knees; 56.0%) and syndromic in 55 (74 knees; 44.0%). The mean age at surgery was 11.5 years (range 4-18) and was significantly lower in syndromic patients. Syndromic patients also exhibited more severe clinical pattern at presentation, based on the Parikh and Lykissas score. The mean follow-up was 5.3 years (range 1.0-15.4). Redislocation occurred in 19 cases, with 10 cases requiring further realignment. The Parikh and Lykissas score and the presence of congenital ligamentous laxity were independent predictors of failure. A total of 22 knees in 18 patients required additional surgical procedures. The post-operative Kujala score was significantly lower in patients with syndromic patellar instability.

CONCLUSIONS

The type of instability and the presence of underlying syndromes negatively affect the rate of redislocation and the clinical and functional outcome following patellar realignment through the three-in-one procedure. We recommend the consideration of alternative surgical strategies, especially in children with severe syndromic patellar dislocation.

MPFL repair after acute first-time patellar dislocation results in lower redislocation rates and less knee pain compared to rehabilitation: a systematic review and meta-analysis

PURPOSE

This study aimed to explore the efficacy of medial patellofemoral ligament (MPFL) repair versus nonoperative rehabilitation treatment on the rate of patellar redislocation and functional outcomes in skeletally mature patients with traumatic, first-time patellar dislocations.

MATERIALS AND METHODS

MEDLINE, PubMed and EMBASE were searched from database inception to May 2022 for studies examining the management options for acute first-time patellar dislocations. This study was conducted in accordance with PRISMA and R-AMSTAR guidelines. Data on redislocation rates, functional outcomes including the Kujala score for anterior knee pain, and complication rates were extracted. A meta-analysis was used to pool the mean postoperative Kujala score and calculate the proportion of patients sustaining redislocations using a random effects model. Quality assessment of included studies was performed for all included studies using the MINORS and Detsky scores.

RESULTS

This review included a total of 25 studies and 1,361 patients. The pooled mean redislocation rate in 15 studies comprising 798 patients in the rehabilitation group was 30% (95% CI 25-36%, I² = 65%). Moreover, the pooled mean redislocation rate in 10 studies comprising 170 patients undergoing MPFL repair was 7% (95% CI 3-12%, I² = 30%). The pooled mean postoperative Kujala score in 8 studies comprising 396 patients in the rehabilitation group was 82.5 (95% CI 78.3-86.8, I² = 91%), compared to a score of 88 (95% CI 87-90, I² = 76%) in 3 studies comprising 94 patients in the repair group. Range of motion deficits was reported in 3.8% of 893 patients in the rehabilitation group and 2.0% of 205 patients in the repair group.

CONCLUSION

MPFL repair resulted in a lower rate of redislocation, less knee pain, and noninferiority with respect to a range of motion deficits compared to nonoperative treatment for the management of acute first-time patellar dislocations.

LEVEL OF EVIDENCE

IV.

Patellar Instability

➢

Certain anatomic factors, such as patella alta, increased tibial tubercle-trochlear groove distance, rotational deformity, and trochlear dysplasia, are associated with an increased risk of recurrent patellar instability.

➢

The presence of a preoperative J-sign is predictive of recurrent instability after operative management.

➢

Isolated medial patellofemoral ligament reconstruction may be considered on an individualized basis, considering whether the patient has anatomic abnormalities such as valgus malalignment, trochlear dysplasia, or patella alta in addition to the patient activity level.

➢

More complex operative management (bony or cartilaginous procedures) should be considered in patients with recurrent instability, malalignment, and certain anatomic factors.

MPFL reconstruction results in lower redislocation rates and higher functional outcomes than rehabilitation: a systematic review and meta-analysis

PURPOSE

To determine the effect of early MPFL reconstruction versus rehabilitation on the rate of recurrent patellar dislocations and functional outcomes in skeletally mature patients with traumatic, first-time patellar dislocation.

METHODS

Three online databases MEDLINE, PubMed and EMBASE were searched from database inception (1946, 1966, and 1974, respectively) to August 20th, 2021 for literature addressing the management of patients sustaining acute first-time patellar dislocations. Data on redislocation rates, functional outcomes using the Kujala score, and complication rates were recorded. A meta-analysis was used to pool the mean postoperative Kujala score, as well as calculate the proportion of patients sustaining redislocation episodes using a random effects model. Quality assessment of included studies was performed for all included studies using the MINORS and Detsky scores.

RESULTS

A total of 19 studies and 1,165 patients were included in this review. The pooled mean redislocation rate in 14 studies comprising 734 patients in the rehabilitation group was 30% (95% CI 25-36%, I² = 67%). Moreover, the pooled mean redislocation rate in 5 studies comprising 318 patients undergoing early MPFL reconstruction was 7% (95% CI 2-17%, I² = 70%). The pooled mean postoperative Kujala anterior knee pain score in 7 studies comprising 332 patients in the rehabilitation group was 81 (95% CI 78-85, I² = 78%), compared to a score of 87 (95% CI 85-89, I² = 0%, Fig. 4) in 3 studies comprising 54 patients in the reconstruction group.

CONCLUSION

Management of acute first-time patellar dislocations with MPFL reconstruction resulted in a lower rate of redislocation of 7% in the reconstruction group vs 30% in the rehabilitation group and a higher Kujala score compared to the rehabilitation group. The information this review provides will help surgeons guide their decision to choose early MPFL reconstruction versus rehabilitation when treating patients with first-time patellar dislocations and may guide future studies on the topic.

LEVEL OF EVIDENCE

IV.

Many Radiographic and Magnetic Resonance Imaging Assessments for Surgical Decision Making in Pediatric Patellofemoral Instability Patients Demonstrate Poor Interrater Reliability

PURPOSE

To evaluate the interrater reliability of several common radiologic parameters used for patellofemoral instability and to attempt to improve reliability for measurements demonstrating unacceptable interrater reliability through consensus training.

METHODS

Fifty patients with patellar instability between the ages of 10 and 19 years were selected from a prospectively enrolled cohort. For measurements demonstrating unacceptable interrater reliability (intraclass correlation coefficient [ICC]: <0.6), raters discussed consensus methods to improve reliability and re-examined a subset of 20 images from the previous set of images. If reliability was still low after the second round of assessment, the measure was considered unreliable.

RESULTS

Of the 50 included subjects, 22 (44%) were male and the mean age at the time of imaging was 14 ± 2 years. With 1 or fewer consensus training sessions, the interrater reliability of the following radiograph indices were found to be reliable: trochlea crossing sign (ICC: 0.625), congruence angle (ICC: 0.768), Caton-Deshamps index (ICC: 0.644), lateral patellofemoral angle (ICC: 0.768), and mechanical axis deviation on hip-to-ankle alignment radiographs (ICC: 0.665-0.777). Reliable magnetic resonance imaging (MRI) indices were trochlear depth (ICC: 0.743), trochlear bump (ICC: 0.861), sulcus angle (ICC: 0.684), patellar tilt (ICC: 0.841), tibial tubercle to trochlear groove distance (ICC: 0.706), effusion (ICC: 0.866), and bone marrow edema (ICC: 0.961).

CONCLUSIONS

With 1 or fewer consensus training sessions, the interrater reliability of the following patellofemoral indices were found to be reliable for trochlear morphology: trochlea crossing sign and congruence angle on radiograph and trochlear depth, trochlear bump, and sulcus angle on MRI. Reliable patellar position measurements included: Caton-Deshamps index and lateral patellofemoral angle on radiograph and patellar tilt and tibial tubercle to trochlear groove distance on MRI. Additional global measurements (e.g., mechanical axis deviation on standing radiographs) and MRI assessments demonstrated acceptable reliability.

LEVEL OF EVIDENCE

II, prospective diagnostic study.

MRI as the optimal imaging modality for assessment and management of osteochondral fractures and loose bodies following traumatic patellar dislocation: a systematic review

PURPOSE

To assess the imaging modalities used for diagnosis, as well as the management decisions of patients with osteochondral fractures (OCF) and loose bodies following traumatic patellar dislocation.

METHODS

According to the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA), MEDLINE, EMBASE, Web of Science, and PubMed were searched for results from January 1, 2000, to May 18, 2021, in two subsequent searches for English language studies that presented data on traumatic patellar dislocation. Quality of selected papers was assessed using the Methodological Index for Non-Randomised Studies (MINORS) and the Risk of Bias (RoB) 2.0 protocol. Results were qualitatively synthesised, and descriptive statistics were calculated.

RESULTS

Forty studies totalling 3074 patients (1407 females) were included for the analysis. The mean age was 18.9 years (range 0-69). The population included 2446 first-time dislocations. The imaging modalities used were: 71.1% MRI, 52.6% plain radiography, 12.1% CT, and 0.68% ultrasound. In the 25 studies that reported the number of OCF, a total of 38.3% of patients were found to have OCF. 43.3% of patients with a first-time dislocation, and 34.7% of patients with previous dislocations, had at least one OCF. In the included paediatric studies (maximum age ≤ 18), the presence of OCF was detected by plain radiography in 10.1% of patients, MRI in 76.6% of patients, and CT in 89.5% of patients. For management of an OCF, the surgical options include fixation for larger pieces, excision for smaller pieces, and conservative management on a case-by-case basis.

CONCLUSIONS

Based on the current available evidence, assessment and management of patellar dislocations and subsequent OCFs vary, with radiography and MRI as the main imaging modalities on presentation and particular benefit for MRI in the paediatric population. Findings from this study suggest the highest rate of OCF detection with MRI, and thus, surgeons should consider routinely ordering an MRI in patients with first-time patellar dislocation. Regarding management of OCFs, the main indication for fixation was large fragments, while smaller and poor-quality fragments are excised. Few studies choose conservative management of OCFs due to later requirements for surgical management. Future work should focus on large, high-quality studies, and implementation of randomised control trials to form guidelines for imaging patellar dislocations and management of OCFs.

LEVEL OF EVIDENCE

Level IV.

Treatment of Osteochondral Fractures After Acute Patellofemoral Instability: A Critical Analysis Review

»

An osteochondral fracture (OCF) of the patella or the femur is a frequent sequela after an episode of acute patellofemoral instability.

»

Patients commonly present with anterior knee pain after direct trauma to the patella or a noncontact twisting injury.

»

Radiographs and magnetic resonance imaging (MRI) are the most common imaging modalities that are used to diagnose OCFs.

»

Arthroscopy may be indicated in cases of displaced OCFs, and the decision regarding osteochondral fragment fixation or loose body removal depends on fragment size, location, and extent of injury.

»

Most of the current literature suggests worse outcomes for patients with OCFs who undergo nonoperative treatment, no significant differences in outcomes for patients sustaining an acute patellar dislocation with or without an OCF, and inconclusive results concerning outcomes for patients treated with loose body removal compared with fixation.

»

Current outcome data are limited by studies with low levels of evidence; therefore, well-designed randomized controlled trials are needed.

Trochlear Dysplasia as Shown by Increased Sulcus Angle Is Associated With Osteochondral Damage in Patients With Patellar Instability

PURPOSE

The primary study objective was to describe the incidence of osteochondral damage (OD) in our cohort of patients with patellar instability (PI). The secondary objective was to assess for associations between patient demographic characteristics, duration of PI, and quantitative radiographic measurements of anatomic risk factors for PI and OD in this cohort.

METHODS

A retrospective chart review identified patients treated for PI at a tertiary referral center between 2013 and 2018. Patients were evaluated for osteochondral injury with either magnetic resonance imaging if treated nonoperatively or operative reports if treated surgically. The Caton-Deschamps ratio, proximal tibial tubercle-to-trochlear groove (pTT-TG) distance, distal tibial tubercle-to-trochlear groove (dTT-TG) distance, lateral trochlear inclination (LTI) angle, lateral patellar inclination (LPI) angle, and sulcus angle were calculated from magnetic resonance imaging scans. Trochlear dysplasia is an important risk factor for PI that can be reliability quantified by the pTT-TG distance, dTT-TG distance, LTI angle, sulcus angle, and LPI angle. Demographic data including age at first instability event, sex, body mass index, symptom duration, and number of dislocations were documented.

RESULTS

A total of 125 knees in 118 patients (average age, 13.9 ± 3.4 years; 48% female patients) with PI were identified. Within this cohort, 67% were treated surgically and 53% had OD. No association was identified between osteochondral injury and age, sex, body mass index, symptom duration, LTI angle, LPI angle, dTT-TG distance, pTT-TG distance, or number of dislocations. An increased sulcus angle (more dysplasia) showed a statistically significant association with osteochondral pathology (P = .021), and higher sulcus angles were statistically significantly associated with acute osteochondral fracture compared with chondral injury (P = .001).

CONCLUSIONS

Using quantitative analysis of trochlear dysplasia, this study identified a significant association between trochlear dysplasia (sulcus angle) and the incidence of OD in our cohort of patients with PI. The frequency of dislocation or subluxation and patient demographic characteristics were not significantly associated with OD.

LEVEL OF EVIDENCE

Level III, retrospective prognostic study.

Medial Patellofemoral Ligament Repair or Medial Advancement: Is There a Role?

Patellar instability is one of the most prevalent knee disorders, with dislocations occurring in 5 to 43 cases per 10,000 annually. Traumatic patellar dislocation can result in significant morbidity and is associated with patellofemoral chondral injuries and fractures, medial soft tissue disruption, pain, and reduced function, and can lead to patellofemoral osteoarthritis. Chronic and recurrent instability can lead to deformation and incompetence of the medial soft tissue stabilizers. Despite recent gains in understanding the pathoanatomy of this disorder, the management of patients with this condition is complex and remains enigmatic.

Iyengar-Botchu (IB) confluence of the medial knee- anatomy and clinico-radiological review

The Iyengar-Botchu confluence is a quadrilateral space on the medial side of the knee. Due to the presence of unique anatomical structures, this region is prone to injuries. The aim of this pictorial review is to illustrate an anatomical description of the structures, which form the IB complex confluence. Clinico-pathological correlation of common conditions associated with these structures will increase awareness of injuries in this area. A complementary imaging guidance will support clinical diagnosis and appropriate patient management.

Novel method for diagnosing lateral patellar compression syndrome using X-ray: a retrospective case-control study

Background

A well-established reference is lacking for diagnosing lateral patellar compression syndrome (LPCS), and this diagnosis currently depends on clinicians' subjective judgment and several examination results. X-rays are primarily used to diagnose LPCS, but they have low detection rates of patellar tilt using the congruence angle (CA) and patellar tilting angle (PTA).

Methods

We enrolled 87 patients (31 men and 56 women; mean age: 42.11±15.33 years) between 2016 and 2019 and divided them as per diagnosis into three groups of 29 each: LPCS, patellar dislocation (PD, control), and meniscus tear (MT, negative control) groups. A senior radiologist and the chief physician of sports medicine examined their patellar axial radiographs of the knee in 30° flexion using a computer imaging system, measuring LPCA, CA and PTA. Univariate analysis of variance and Kruskal-Wallis H test were used to compare measurement data with normal distribution and non-normal distribution, respectively. Bonferroni correction was used to analyze different indicators for different groups. The area under the curve (AUC) was calculated to verify the value of LPCA in the initial diagnosis of LPCS.

Results

LPCA (19.88±7.49) was significantly higher in LPCS group than in MT (13.68±4.69) and PD groups (10.16±4.43) (P<0.01) and was also significantly higher on affected side than on healthy side (16.44±5.00) (P=0.04). LPCA >13.9° had sensitivity and specificity of 89.66% and 68.97%, respectively, for LPCS diagnosis (AUC: 0.82, 95% confidence interval: 0.719-0.891, P<0.001).

Conclusions

We demonstrated that LPCA measured using an axial patellar radiograph of the knee in 30° flexion is high in patients with LPCS, and it may be used for diagnosing LPCS.

The majority of patellar avulsion fractures in first-time acute patellar dislocations included the inferomedial patellar border that was different from the medial patellofemoral ligament attachment

PURPOSE

Accurate assessment of the locations of patellar avulsion fractures in acute patellar dislocations is clinically relevant for decision making for treatment. The study aim was to classify the locations of patellar avulsion fractures with a focus on the ligament attachments of medial stabilizing structures.

METHODS

Out of 131 first-time acute traumatic patellar dislocations, 61 patients had patellar fractures. Subsequently, 10 patients with isolated osteochondral fractures of the articular surface in the patella were excluded. Finally, 51 patients (34 females and 17 males, average age: 18.5 years, 95% CI 16.1-20.9) were included in the study cohort. Based on the locations of the patellar attachment, the patients were divided into three groups: the superior group [medial patellofemoral ligament (MPFL) attachment], inferior group [medial patellotibial ligament (MPTL)/medial patellomeniscal ligament (MPML) attachment], and mixed group.

RESULTS

In the patellar avulsion group (51 patients), the superior group, mixed group, and inferior group contained 8/51 (16%), 12/51 (24%), and 31/51 (61%) patients, respectively.

CONCLUSIONS

This study showed that 84% of the patellar avulsion fractures were located in the inferomedial patellar border, which consisted of MPTL/MPML attachments that were clearly different from the true "MPFL" attachment at the superomedial patellar border. In terms of the clinical relevance, the acute surgical repair of MPTL/MPML attachments in the inferomedial patellar border may not sufficiently control the patella if optimal management of the MPFL is not performed.

LEVEL OF EVIDENCE

IV.

Initial conservative treatment of osteochondral fracture of the patella following first-time patellar dislocation

Background

There has been no gold standard of the initial treatment strategy for acute patellar dislocation (APD) with osteochondral fracture (OCF). Hence the study aim is firstly, to review and compare clinical outcomes of patients who underwent conservative treatment for APD with or without OCF. Secondly, to characterize the location and size of fracture fragment.

Methods

Sixty-nine consecutive patients who were retrospectively evaluated after first-time APD over a 2- year period were divided into two groups (group 1 (n = 24): APD with OCF and group 2 (n = 45): APD only). Magnetic resonance imaging (MRI) was used to assess patients with APD and OCF from the medial patella. All patients were treated with a supervised course of immobilization followed by progressive range of motion and strength exercise protocol. History of a recurrent dislocation, radiologic and functional scores were analyzed.

Results

Redislocation rate was 31.2% in group 1 and 26.6% in group 2, showing no significant difference between the two groups (p = 0.690). Intergroup differences in terms of final Kujala and IKDC scores were not significant (p = 0.117 and p = 0.283, respectively). Fracture sites of the patella in group 1 were classified as follows: patellar medial margin (12), inferomedial facet (7), and inferomedial facet involving central ridge (5). In the subgroup of patient with OCF of the inferomedial facet of the patella, the fragments were found in the lateral gutter and did not cause pain or mechanical symptoms. Thus, loose body removal was not performed. However, all five patients with large OCF involving the central ridge of the patella failed non-operative treatment with recurrent dislocations, ultimately requiring fragment refixation and medial retinacular imbrication.

Conclusions

First, APD patients with OCFs of medial margin or inferomedial facet showed similar redislocation rates and functional knee scores with those without OCFs after conservative treatment. Second, initial conservative treatment failed in some APD patients with large OCF, especially when OCFs were fractured from inferomedial facet involving central ridge. Surgery should be considered with this type.

Incidence of second-time lateral patellar dislocation is associated with anatomic factors, age and injury patterns of medial patellofemoral ligament in first-time lateral patellar dislocation: a prospective magnetic resonance imaging study with 5-year follow-up

PURPOSE

To examine the predictors of the second-time lateral patellar dislocation (LPD) in patients after acute first-time LPD in a 5-year follow-up.

METHODS

Data were collected prospectively from patients after acute first-time LPD with conservative treatment. Factors included sex, age at the first-time LPD, anatomical variants [trochlear dysplasia, patellar height, tibial tuberosity-trochlear groove (TT-TG) distance], and injury patterns of medial patellofemoral ligament (MPFL) in acute first-time LPD. Logistic regression was carried out to identify the independent risk factors for the incidence of the second-time LPD.

RESULTS

The incidence rate of a second-time LPD was 35.5% (59 of 166) in the 5-year follow-up. Univariate analysis revealed significant differences in the incidence rate of the second-time LPD among age at the first-time LPD (P = 0.04), trochlear dysplasia (P = 0.003), patella height (P = 0.017) and the TT-TG distance (P = 0.027). Risk factors for the second-time LPD were age < 18 years at the first-time LPD [odds ratio (OR) 4.088], low-grade trochlear dysplasia (OR 7.214), high-grade trochlear dysplasia (OR 18.945), patella alta (OR 8.416), elevated TT-TG distance (OR 12.742), complete MPFL tear at its isolated femoral-side (OR 6.04) and complete combined MPFL tear (OR 5.851).

CONCLUSIONS

Trochlear dysplasia, elevated TT-TG distance, patella alta, age < 18 years at the first-time LPD, complete MPFL tear at its isolated femoral-side and complete combined MPFL tear in the first-time LPD are independently associated with a higher incidence rate of the second-time LPD.

LEVEL OF EVIDENCE

III.

Effective patellofemoral joint stabilization and low complication rates using a hardware-free MPFL reconstruction technique with an intra-operative adjustment of the graft tension

PURPOSE

Even if medial patellofemoral ligament (MPFL) reconstruction is a proven method, complications such as implant loosening, patella fractures, recurrent luxations, knee pain or knee stiffness are frequently described. Besides a correct tunnel positioning and implant-specific complications, this might be caused by difficulties with an appropriate graft tensioning. The study presented here is a necessary first step in exploring our technique of a double-limbed, hardware-free MPFL reconstruction, which provides another way to test and adjust the graft tension before permanent fastening.

METHODS

Thirty consecutive patients (m/f = 18/12) with recurrent dislocations were evaluated after a mean follow-up of 24 months. Patients who had additional procedures such as a trochleoplasties, tibial tubercle transfers and derotational osteotomies were not included. Besides a standardized clinical examination, different scorings and possible complications were evaluated.

RESULTS

The mean Kujala score improved significantly from 57 ± 15 to 92 ± 10. The Lysholm and IKDC score increased significantly from 59 ± 11 to 95 ± 6 and from 49 ± 9 to 89 ± 9, respectively. No patient reported a re-dislocation, subluxation or showed a positive apprehension. A total of 23 patients were engaged in regular physical activities. All but one, who lost interest, returned to the same sports. Because some did not follow our recommendation to return to sports after a rehab of at least 10-12 weeks, the period for a return was relatively short (median of 12 weeks, range 3-25 weeks). Four patients reported a moderate anterior knee pain only occurring after increased loads such as longer runs or workouts. One of these showed a slight flexion deficit of less than 20°. A severe motion deficit or stiffness was not noticed.

CONCLUSIONS

Even if a larger, clinical outcome study is needed to ensure the efficacy and safety of our method, it seems to provide a good clinical outcome, a correspondingly high satisfaction and a low incidence of complications. The possibility to adjust graft tension might help in minimizing complications caused by difficulties with an appropriate graft tension.

LEVEL OF EVIDENCE

IV.

Clinical Outcomes After the Nonoperative Management of Lateral Patellar Dislocations: A Systematic Review

Background:

The first-line treatment for patellar dislocations is often nonoperative and consists of physical therapy and immobilization techniques, with various adjuncts employed. However, the outcomes of nonoperative therapy are poorly described, and there is a lack of quality evidence to define the optimal intervention.

Purpose:

To perform a comprehensive review of the literature and assess the quality of studies presenting patient outcomes from nonoperative interventions for patellar dislocations.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

The MEDLINE, AMED, Embase, CINAHL, Cochrane Library, PEDro, and SPORTDiscus electronic databases were searched through July 2017 by 3 independent reviewers. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed. Study quality was assessed using the CONSORT (Consolidated Standards for Reporting Trials) criteria for randomized controlled trials and the Newcastle-Ottawa Scale for cohort studies and case series.

Results:

A total of 25 studies met our inclusion criteria, including 12 randomized controlled trials, 7 cohort studies, and 6 case series, consisting of 1066 patients. Studies were grouped according to 4 broad categories of nonoperative interventions based on immobilization, weightbearing status, quadriceps exercise type, and alternative therapies. The most commonly used outcome measure was the Kujala score, and the pooled redislocation rate was 31%.

Conclusion:

This systematic review found that patient-reported outcomes consistently improved after all methods of treatment but did not return to normal. Redislocation rates were high and close to the redislocation rates reported in natural history studies. There is a lack of quality evidence to advocate the use of any particular nonoperative technique for the treatment of patellar dislocations.

Functional testing and return to sport following stabilization surgery for recurrent lateral patellar instability in competitive athletes

PURPOSE

Medial patellofemoral ligament (MPFL) reconstruction and tibial tubercle osteotomy are commonly used to treat recurrent lateral patellar instability, yet there are limited available data on return to sport (RTS) following these procedures. The purpose of this study is to evaluate patient factors associated with excellent functional outcomes, including successful RTS, following surgical stabilization including MPFL reconstruction in competitive athletes with recurrent lateral patellar instability.

METHODS

Athletes undergoing primary MPFL reconstruction for recurrent lateral instability from 2005 to 2013 were identified at a single institution. Concomitant procedures, such as tibial tubercle osteotomy (TTO), were included. Patient demographic information, including BMI, gender, age, and pre-injury Tegner score, was recorded. In addition, radiographs were reviewed for pre-operative patellar height (Caton-Deschamps index) and trochlear dysplasia (Dejour classification). All patients underwent a standardized rehabilitation/post-operative protocol, with isokinetic strength and functional testing being performed at 6 months post-operatively. Final Tegner scores, RTS status, subjective instability ratings, and Kujala scores were collected at a minimum of 2 years. Chi-squared analysis for categorical variables and Wilcoxon rank-sum analysis for continuous variables were used to determine the relationship between the previously mentioned patient and knee characteristics with isokinetic data, RTS status, or Kujala scores.

RESULTS

Thirty-nine athletes (23 male, 16 female) at a mean age of 17.5 ± 2.9 years (range, 13-26) underwent primary MPFL reconstruction (32 autografts, seven allografts) for recurrent patellar instability with a mean follow-up of 47.0 ± 16.4 months. Sixteen patients (41%) underwent concomitant tibial tubercle osteotomies. Isokinetic data collected at 6 months post-operatively demonstrated mean knee flexion and extension strength deficits of 15.8 ± 10.1% and 21.4 ± 14.3%, respectively, compared to the contralateral leg (p < 0.001 for both). Patients who underwent concomitant tibial tubercle osteotomy (p = 0.04), males (p = 0.01) and those with patella alta (p = 0.04) had weaker 6-month isokinetic testing. Thirty-three of the thirty-nine (85%) athletes were able to RTS at a mean of 8.1 ± 3.9 months. Patients undergoing MPFL with concomitant TTO (p = 0.02) returned to sport at a slower rate. One patient (3%) reported an episode of recurrent dislocation requiring revision surgery. Kujala and Tegner scores at final follow-up were 91.1 ± 6.3 and 6 (range, 4-9), respectively.

CONCLUSION

Surgical stabilization including MFPL reconstruction for recurrent lateral patellar instability is an effective procedure for returning athletes to competitive sports. However, strength deficits persist at 6 months after surgery, especially in those undergoing concomitant TTO, which may delay return to sport. Physicians can use these results to counsel patients that return to competitive sports is safe with good clinical outcomes and low rate of recurrence at 4-year follow-up; however, predisposing factors, like a lateralized tibial tubercle, should be addressed if necessary, but athletes should be counselled that a slower recovery and longer return to sport time may be expected.

LEVEL OF EVIDENCE

IV.

Correlation analysis between injury patterns of medial patellofemoral ligament and vastus medialis obliquus after acute first-time lateral patellar dislocation

PURPOSE

To evaluate the correlation between injury patterns of the medial patellofemoral ligament (MPFL) and vastus medialis obliquus (VMO) after acute first-time lateral patellar dislocation (LPD) in adults.

METHODS

Magnetic resonance imaging (MRI) was prospectively performed in 132 consecutive adults with acute first-time LPD. Images were acquired and evaluated using standardized protocols. Injury patterns of MPFL were grouped by location and severity for analysis of the prevalence of VMO injury.

RESULTS

MRI demonstrated VMO injury in 63 (47.7%) patients. Twenty (38.5%) and 43 cases (56.6%) were present in partial and complete MPFL tear subgroups, respectively. Compared with partial MPFL tears, complete tears showed a higher prevalence of VMO injury (P = 0.044). The mean coronal (28.5 mm) and mean sagittal VMO elevations (20.7 mm) were higher in the complete MPFL tear subgroup than in the partial tear subgroup (19.8 mm, P = 0.005; 11.9 mm, P < 0.001). No correlations were identified between the prevalence of VMO injury and location subgroups of MPFL injury (n.s.). Mean VMO elevations were higher in isolated femoral-side (FEM) and combined MPFL tear (COM) subgroups (mean coronal VMO elevation of 29 mm and mean sagittal VMO elevation of 20.8 mm in the FEM subgroup; mean coronal VMO elevation of 29.6 mm and mean sagittal VMO elevation of 23.1 mm in the COM subgroup) than in the isolated patellar-side MPFL tear (PAT) subgroup (P = 0.022, P < 0.001) (mean coronal VMO elevation of 20.7 mm and mean sagittal VMO elevation of 10.6 mm).

CONCLUSIONS

Complete MPFL tear predisposes to VMO injury and has a higher elevation of torn VMO after acute first-time LPD in adults. Isolated femoral-side and combined MPFL tears predispose to higher elevation of torn VMO.

LEVEL OF EVIDENCE

IV.

Anatomic patellar instability risk factors in primary lateral patellar dislocations do not predict injury patterns: an MRI-based study

PURPOSE

The primary goal was to describe the injury patterns in a population of primary (first time) lateral patellar dislocators (LPD) to lend clarity to commonly held notions about injury patterns in this population.

METHODS

A prospective study identifying patients presenting with LPD between 2008 and 2012. Inclusion criteria were a history and physical exam consistent with primary LPD, and an MRI consistent with the diagnosis without other significant ligamentous injury. On MRI, location of cartilage, medial patellofemoral ligament (MPFL) injury, and bone bruising were noted. Severity was categorized as partial or complete for MPFL and cartilage lesions. Anatomic patellar instability risk factors (patella alta, trochlear dysplasia, increased TT-TG, and lateral patella tilt) were recorded and compared to the injury patterns.

RESULTS

This study involved 157 patients; 107 patients were skeletally mature. Of the 157 patients, 26 had surgery for this injury due to clinician-perceived need for cartilage debridement. MPFL injury severity was complete rupture (N = 69, 44%), partial (N = 67, 43%), and none (N = 19, 13%). MPFL injury location was isolated femoral (N = 16, 10%), isolated patella (N = 26, 17%), isolated mid-substance (0%), multiple locations (N = 95, 61%), and none (N = 20, 13%). Chondral injury location was patella (N = 67, 43%), lateral femoral condyle (N = 11, 7%), multiple locations (N = 53, 34%), and none (N = 26, 17%). A majority (61%) of patellar chondral lesions were at its inferomedial aspect; all medial patellar retinacular partial injuries involved the inferomedial aspect of the patella, consistent with the insertion of the medial patellotibial ligament (MPTL). Skeletally immature patients had a greater risk of isolated patellar MPFL and chondral injury. No clear relationship was found between/across the location and/or severity of bone bruising, MPFL, or chondral injury.

CLINICAL RELEVANCE

Underlying anatomic patellar instability risk factors defined by MRI, do not predict injury patterns. MPFL and chondral injury, as well as bone bruising, are common following LPD. The medial patellotibial ligament is torn in patellar-based medial retinacular injuries, based on MRI injury location. Skeletal immaturity plays a role in the location of the injury pattern with isolated patellar-based MPFL/chondral injury being more common in the skeletally immature patient. Sex does not appear to be a factor in injury patterns after primary LPD. Knowledge of these injury trends will help focus the clinician in injury evaluation when managing primary patellar dislocations.

LEVEL OF EVIDENCE

Case series, Level IV.

The Correlation between the Injury Patterns of the Medial Patellofemoral Ligament in an Acute First-Time Lateral Patellar Dislocation on MR Imaging and the Incidence of a Second-Time Lateral Patellar Dislocation

Objective

To evaluate the correlation between the injury patterns of the medial patellofemoral ligament (MPFL) on magnetic resonance imaging in an acute first-time lateral patellar dislocation (LPD) and incidence of a second-time LPD.

Materials and Methods

Magnetic resonance images were prospectively analyzed in 147 patients after an acute first-time LPD with identical nonoperative management. The injury patterns of MPFL in acute first-time LPDs were grouped by location and severity for the analysis of the incidence of second-time LPD in a 5-year follow-up. Independent t tests, chi-square tests and Kruskal-Wallis tests were performed as appropriate.

Results

Forty-six cases (46/147, 31.3%) of second-time LPD were present at the 5-year follow-up. Fourteen (14/62, 22.6%) and 31 cases (31/80, 38.8%) were present in the partial and complete MPFL tear subgroups, respectively. Twenty-five cases (25/65, 38.5%), 11 cases (11/26, 42.3%), and 8 cases (8/47, 17%) were present in the isolated femoral-side MPFL tear (FEM), combined MPFL tear (COM), and isolated patellar-side MPFL tear (PAT) subgroups, respectively. Compared with the partial MPFL tears, complete tears showed higher incidence of a second-time LPD (p = 0.04). The time interval between the two LPDs was shorter in the complete MPFL tear subgroup (24.2 months) than in the partial tear subgroup (36.9 months, p = 0.001). Compared with the PAT subgroup, the FEM and COM subgroups showed a higher incidence of a second-time LPD (p = 0.025). The time intervals between the two LPDs were shorter in the FEM and COM subgroups (20.8 months and 19.2 months) than in the PAT subgroup (32.5 months, p = 0.049).

Conclusion

A complete MPFL tear, isolated femoral-side tear and combined tear in a first-time LPD predispose a second-time LPD.

Origin and insertion of the medial patellofemoral ligament: a systematic review of anatomy

PURPOSE

The medial patellofemoral ligament (MPFL) is the major medial soft-tissue stabiliser of the patella, originating from the medial femoral condyle and inserting onto the medial patella. The exact position reported in the literature varies. Understanding the true anatomical origin and insertion of the MPFL is critical to successful reconstruction. The purpose of this systematic review was to determine these locations.

METHODS

A systematic search of published (AMED, CINAHL, MEDLINE, EMBASE, PubMed and Cochrane Library) and unpublished literature databases was conducted from their inception to the 3 February 2016. All papers investigating the anatomy of the MPFL were eligible. Methodological quality was assessed using a modified CASP tool. A narrative analysis approach was adopted to synthesise the findings.

RESULTS

After screening and review of 2045 papers, a total of 67 studies investigating the relevant anatomy were included. From this, the origin appears to be from an area rather than (as previously reported) a single point on the medial femoral condyle. The weighted average length was 56 mm with an 'hourglass' shape, fanning out at both ligament ends.

CONCLUSION

The MPFL is an hourglass-shaped structure running from a triangular space between the adductor tubercle, medial femoral epicondyle and gastrocnemius tubercle and inserts onto the superomedial aspect of the patella. Awareness of anatomy is critical for assessment, anatomical repair and successful surgical patellar stabilisation.

LEVEL OF EVIDENCE

Systematic review of anatomical dissections and imaging studies, Level IV.

Pediatric Lateral Patellar Retinacular Sleeve Avulsion

A 10-year-old girl presented to the physical therapist with acute left knee pain, after sprinting that morning. She reported a pop and lateral knee pain, which caused her to stop her run. The physical therapist referred the patient for radiographs that day, which showed a possible lateral patellar avulsion. Magnetic resonance imaging was performed the following day, given the poor accuracy of radiographs in patellar avulsions, which confirmed a lateral patellar retinacular sleeve avulsion. J Orthop Sports Phys Ther 2017;47(10):815. doi:10.2519/jospt.2017.6616.

Diagnosis and Management of Traumatic Patellar Instability in the Pediatric Patient

Instability of the patella is a common cause of knee pain and dysfunction in pediatric and adolescent patients and can be due to several factors. Although some patients will recall a specific traumatic event others may not, requiring the diagnosis to be made on the basis of physical examination and imaging. Congenital dislocation and connective tissue disorders should also be considered, even in the setting of trauma. There are radiographic parameters that may identify causes of instability such as trochlear and patellar abnormalities, and magnetic resonance imaging can identify signs of trauma such as bony edema, loose osteochondral fragments, and increased tibial tubercle-trochlear groove distance. The first line of treatment for instability is most commonly nonoperative in nature; however, there are many options for operative management in the event of severe chondral injury or recurrent dislocation. Surgical management to best restore stability of the patellofemoral joint varies depending on the skeletal maturity of the patient and the source of instability (ligamentous, osteocartilaginous, or both). A combination of soft tissue, bony, and anatomic ligamentous repair or reconstruction is used to best augment patellar tracking and optimize patient outcome. [Orthopedics. 2017; 40(5):e749-e757.].

Comparative analysis of medial patellofemoral ligament length change pattern in patients with patellar dislocation using open-MRI

PURPOSE

Medial patellofemoral ligament (MPFL) reconstruction has become a common form of treatment for recurrent patellar dislocation. This study was performed using open-MRI to compare the length change pattern of MPFL in patients with a history of patellar dislocation to that in healthy subjects.

METHODS

The subjects comprised 10 knees of 8 males and 13 knees of 12 females with a history of one or more patellar dislocations. The length of the MPFL was measured using open-MRI in both the leg-extended position and knee-flexed positions to analyse the length change pattern.

RESULTS

The average MPFL lengths were 58.6 ± 6.5 mm and 52.0 ± 4.6 mm for males and females in the extended knee position, respectively. The length change pattern of the MPFL showed slight variation up to a flexion angle of 30° and a clear decrease above 30°. This pattern differed from that of normal MPFL. In terms of morphology, the fibre bundle of the damaged MPFL followed a convex course towards the side of the patellofemoral joint surface at a knee flexion angle of 60°, whereas that of the normal MPFL followed a straight course.

CONCLUSION

The in vivo damaged MPFL length change pattern was specific and differed distinctly from that of normal MPFL. The results of the present study suggested that MPFL fibres with a history of patellar dislocation lack sufficient tension at knee flexion angles of 0°-60°. However, further studies are needed to obtain a better understanding of cases with a patellar dislocation or postsurgical cases of MPFL reconstruction.

LEVEL OF EVIDENCE

III.

The patellofemoral joint: from dysplasia to dislocation

Patellofemoral dysplasia is a major predisposing factor for instability of the patellofemoral joint. However, there is no consensus as to whether patellofemoral dysplasia is genetic in origin, caused by imbalanced forces producing maltracking and remodelling of the trochlea during infancy and growth, or due to other unknown and unexplored factors.The biomechanical effects of patellofemoral dysplasia on patellar stability and on surgical procedures have not been fully investigated. Also, different anatomical and demographic risk factors have been suggested, in an attempt to identify the recurrent dislocators. Therefore, a comprehensive evaluation of all the radiographic, MRI and CT parameters can help the clinician to assess patients with primary and recurrent patellar dislocation and guide management.Patellofemoral dysplasia still represents an extremely challenging condition to manage. Its controversial aetiology and its complex biomechanical behaviour continue to pose more questions than answers to the research community, which reflects the lack of universally accepted guidelines for the correct treatment. However, due to the complexity of this condition, an extremely personalised approach should be reserved for each patient, in considering and addressing the anatomical abnormalities responsible for the symptoms. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160081. Originally published online at www.efortopenreviews.org.

Injury patterns of medial patellofemoral ligament after acute lateral patellar dislocation in children: Correlation analysis with anatomical variants and articular cartilage lesion of the patella

OBJECTIVES

To assess the relationship between injury patterns of medial patellofemoral ligament (MPFL) and anatomical variants and patellar cartilage lesions after acute lateral patellar dislocation (LPD) in children.

METHODS

MR images were obtained in 140 children with acute LPD. Images were acquired and evaluated using standardised protocols.

RESULTS

Fifty-eight cases of partial MPFL tear and 75 cases of complete MPFL tear were identified. Injuries occurred at an isolated patellar insertion (PAT) in 52 cases, an isolated femoral attachment (FEM) in 42 cases and an isolated mid-substance (MID) in five cases. More than one site of injury was identified in 34 cases. Compared with Wiberg patellar type C, Wiberg patellar type B predisposed to complete MPFL tear (P = 0.042). No correlations were identified between injury patterns of MPFL and trochlear dysplasia, patellar height and tibial tuberosity-trochlear groove distance (P > 0.05). Compared with partial MPFL tear, complete MPFL tear predisposed to Grade-IV and Grade-V patellar chondral lesion (P = 0.02). There were no correlations between incidence of patellar cartilage lesion and injury locational-subgroups of MPFL (P = 0.543).

CONCLUSIONS

MPFL is most easily injured at the PAT in children. Wiberg patellar type B predisposes to complete MPFL tear. Complete MPFL tear predisposes to a higher grade of patellar chondral lesion.

KEY POINTS

• MPFL is most easily injured at its patellar insertion in children. • Wiberg patellar type B predisposes to complete MPFL tear. • No correlations between injury patterns of MPFL and other three anatomical variants. • Complete MPFL tear predisposes to higher grade patellar chondral lesion. • No correlations between injury locations of MPFL and patellar cartilage lesion.

MRI-associated classification to evaluate the outcome after autologous reconstruction of the medial patellofemoral ligament: a preliminary study

PURPOSE

Purpose of this study was to establish and validate an MRI-associated classification to graduate postoperative results of MPFL reconstructions.

METHODS

30 autologous MPFL reconstructions of 28 patients were evaluated by two independent raters using MRI. All grafts were assigned to a novel graduation system respecting the graft's anchoring insertions, its MRI signal appearance, continuity and tension and the differentiation relating to the surrounding soft tissue.

RESULTS

All grafts could reliably be assigned to one of the subgroups by both raters. 86.6 % of the grafts could be classified A1 or B1, reflecting a correct positioning and a low to intermediate signal intensity. Only one graft had to be classified C3 (malpositioned, elongated).

CONCLUSION

We were able to establish and validate an MRI-associated classification to graduate the postoperative outcome after MPFL reconstructions. Foresighted, the presented classification might support further decision making in case of unsatisfying postoperative results.

Medial Patellofemoral Ligament Injuries in Children With First-Time Lateral Patellar Dislocations: A Magnetic Resonance Imaging and Arthroscopic Study

BACKGROUND

A lateral patellar dislocation (LPD) is the most common knee injury in children with traumatic knee hemarthrosis. The medial patellofemoral ligament (MPFL), the important passive stabilizer against LPDs, is injured in more than 90% of cases. The MPFL injury pattern is most often defined in adults or in mixed-age populations. The injury pattern in the skeletally immature patient may be different.

PURPOSE

To describe MPFL injuries in the skeletally immature patient by magnetic resonance imaging (MRI), and to compare the results with the injury pattern found at arthroscopic surgery.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This was a prospective series of patients aged 9 to 14 years with acute, first-time traumatic LPDs in whom clinical examinations, radiographs, MRI, and arthroscopic surgery were performed within 2 weeks from the index injury. The MPFL injury was divided into 3 different groups according to the location: patellar site, femoral site, or multifocal. The MPFL injury site was confirmed on MRI by soft tissue edema. The length of the MPFL injury at the patellar site was measured at arthroscopic surgery, and those ≥2 cm were defined as total ruptures.

RESULTS

A total of 74 patients (40 girls and 34 boys; mean age, 13.1 years) were included; 73 patients (99%) had an MPFL injury according to MRI and arthroscopic surgery. The MRI scans showed an isolated MPFL injury at the patellar attachment site in 44 of 74 patients (60%), a multifocal injury in 26 patients (35%), an injury at the femoral site in 3 patients (4%), and no injury in 1 patient (1%). Arthroscopic surgery disclosed an isolated MPFL injury at the patellar site in 60 of 74 patients (81%) and a multifocal injury in 13 patients (18%); the MPFL injury at the patellar site was a total rupture in 49 patients (66%). Edema at the patellar attachment site on MRI was proven to be an MPFL rupture at the same site at arthroscopic surgery in 99% of the patients. A patellar-based injury, isolated or as part of a multifocal injury, was present on MRI in 95% (n = 70) of the patients, with a false-negative rate of 5% (n = 4) of patients compared with arthroscopic surgery.

CONCLUSION

Skeletally immature children are more prone to sustaining an MPFL injury at the patellar attachment site. Arthroscopic surgery and MRI complement each other in the investigation of MPFL injuries.

Classification of Lateral Patellar Instability in Children and Adolescents

There is significant heterogeneity in the literature related to the causes and treatment of patellar instability. To address the multifactorial issue of patellar instability, the first task is to classify the instability pattern. Once a classification system is developed, future studies can differentiate between treatment recommendations and outcomes for each instability pattern. Existing classification systems do not include the entire spectrum of patellar instability patterns. The aim of this article is to review the nomenclature and existing patellar instability classification systems and analyze the different patterns into a comprehensive system.

Injury patterns of medial patellofemoral ligament and correlation analysis with articular cartilage lesions of the lateral femoral condyle after acute lateral patellar dislocation in adults: An MRI evaluation

OBJECTIVES

The purpose of this study was to investigate the injury characteristics of medial patellofemoral ligament (MPFL), and to analyse the correlations between the injury patterns of MPFL and articular cartilage lesions of the lateral femoral condyle in adults with acute lateral patellar dislocation (LPD).

METHODS

Magnetic resonance (MR) images were prospectively obtained in 121 consecutive adults with acute LPD. Images were acquired using standardised protocols and these were independently evaluated by two radiologists.

RESULTS

Forty-eight cases of partial MPFL tear and 71 cases of complete MPFL tear were identified. Injuries occurred at an isolated femoral attachment (FEM) in 48 cases, an isolated patellar insertion (PAT) in 36 cases and an isolated mid-substance (MID) in five cases. More than one site of injury to the MPFL (COM) was identified in 30 cases. The prevalence rate of chondral and osteochondral lesions of the lateral femoral condyle were 4.2% (2/48) and 6.3% (3/48) in the FEM subgroup, 19.4% (7/36) and 22.2% (8/36) in the PAT subgroup and 6.7% (2/30) and 13.3% (4/30) in the COM subgroup, respectively. The PAT subgroup showed significantly higher prevalence rate of chondral and osteochondral lesions in the lateral femoral condyle when compared with the FEM subgroup. The prevalence rate of chondral and osteochondral lesions of the lateral femoral condyle were 8.5% (6/71) and 19.7% (14/71) in the complete MPFL tear subgroup and 10.4% (5/48) and 4.2% (2/58) in the partial MPFL tear subgroup, respectively. The subgroup of the complete MPFL tear showed significantly higher prevalence rate of osteochondral lesions in the lateral femoral condyle when compared with the subgroup of the partial MPFL tear.

CONCLUSIONS

Firstly, the MPFL is most easily injured at the FEM, and secondly at the PAT in adults after acute LPD. The complete MPFL tear is more often concomitant with osteochondral lesions of the lateral femoral condyle than the partial MPFL tear. The isolated patellar-sided MPFL tear is more easily concomitant with chondral lesions and osteochondral lesions of the lateral femoral condyle than the isolated femoral-sided MPFL tear.

Medial Patellofemoral Ligament Reconstruction: A Longitudinal Study Comparison of 2 Techniques with 2 and 5-Years Follow-Up

Background :

The purpose of this study was to compare the results of two popular surgical techniques for medial patellofemoral ligament MPFL reconstruction with a minimum of two-year follow-up.

Methods :

Fifty-eight patients with traumatic tear of the medial patellofemoral ligament were included in one of the two surgical groups. Group 1 MPFLs were reconstructed through graft endobutton fixation and Group 2 through graft anchor fixation into the patella. After two to five-year follow-up, patients were asked to answer knee function questionnaires (Fulkerson and Kujala) as well as the SF-36 life quality score.

Results :

There were no statistical difference among postoperative Kujala, Fulkerson, and SF-36 questionnaires scores between Groups 1 and 2. There were statistical significant differences favorable to patients in Group 1 with a shorter follow-up length (2-5 years) compared to those with a longer period of 5-10 years for both Kujala and Fulkerson scores and no difference for group 2.

Conclusion :

Both medial patellofemoral ligament reconstruction techniques had similar results in a two to ten-year follow-up according to functions and life quality questionnaires. Furthermore, endobutton fixation for the patellar edge of the graft had better results in patients with 2 years of follow-up than those with 5 years. Gender was not significant for surgical results. Moreover, group 1 patients had higher number of complications.