Medial Patellofemoral Ligament Injury Research Articles

Management of Chondral Injuries Associated With Patellar Instability

The treatment of cartilage injuries secondary to patellar instability is multifactorial. These factors include the time frame of patellar instability, the pathoanatomic factors, the extent of symptoms, and the size and location of the cartilage injury. The chondral or osteochondral injury which occurs with acute patellar instability is managed with either reduction and internal fixation or removal. The treatment of the patellar instability component is controversial in the acute setting, especially when there is no need for an osteochondral surgery. In such cases, patellar dislocations are treated nonoperatively. However, if the patient is indicated for surgery for treatment of osteochondral fracture and intra-operatively the medial patellofemoral ligament (MPFL) remains pathologically lax and presents with a discrete MPFL injury site, there is the option of acute repair. Chondral injury associated with recurrent patellar instability may be subdivided into 2 overlapping groups: (1) chondral damage resulting from the instability episodes (distal medial region of the patellar and/or lateral proximal region of the lateral femoral condyle) and (2) chondrosis secondary to the chronic lateral tracking of the patella (chronic patellar subluxation) from patholaxity of the MPFL (lateral chondrosis to patella and trochlea in addition to the injuries sustained from the actual instability episodes). The treatment is based on the patient's chief complaints and the unique underlying pathoanatomy. Many of these patients will have one or more predisposing factors, such as patella alta, trochlear dysplasia, patholaxity of the MPFL and an excessively lateral position of the tibial tuberosity. Therefore, the key to managing this patient population is to address each patient's specific pathoanatomy, which by definition will include addressing the MPFL patholaxity. The goals are to stabilize the patella, normalize patellofemoral contact area and/or forces, and then restore the articular cartilage based on relevant symptoms. As of this writing, treatment options in the United States include debridement, marrow stimulation, osteochondral auto and allograft, autologous chondrocyte implantation, and the use of particulate articular cartilage.

Magnetic Resonance Imaging Characteristics of the Medial Patellofemoral Ligament Lesion in Acute Lateral Patellar Dislocations Considering Trochlear Dysplasia, Patella Alta, and Tibial Tuberosity–Trochlear Groove Distance

The objective of this study was to analyze the injury patterns of the medial patellofemoral ligament (MPFL) in acute lateral patellar dislocations (LPDs) considering the anatomically relevant factors of patellar instability. Knee magnetic resonance images were collected from 73 patients within 7 weeks after LPD, and the injury patterns of the MPFL were evaluated for trochlear dysplasia, for patellar height, and for the tibial tuberosity-trochlear groove (TT-TG) distance. Injury to the MPFL was found in 98.6% of the patients (72 of 73) after the acute LPD, with a complete tear in 51.4% (37 of 72), most frequently localized at the femoral attachment site, and a partial tear in 48.6% (35 of 72). Injury to the femoral origin (Fem), to the midsubstance (Mid), and to the patellar insertion (Pat) of the MPFL was found in 50.0% (36 of 72), 13.9% (10 of 72), and 13.9% (10 of 72), respectively. More than 1 site of injury was found in 22.2% (16 of 72), most frequently as a combined injury at the femoral origin and at the patellar insertion sites (Pat+Fem) (13 of 16). The study population, as well as the Pat, Fem, and Pat+Fem subgroups, showed significantly different values of trochlear dysplasia and patellar height when compared with the control group, whereas the data of the Mid group were not significantly different. In addition, injury at the patellar insertion (Pat) was accompanied by a significantly increased TT-TG distance when compared not only with the control group but also with the Fem, Mid, and Pat+Fem groups. The data from our study indicate that patterns of MPFL injury depend on trochlear dysplasia, patellar height, and TT-TG distance. They show a new aspect in the complex interplay between active, passive, and static stabilizers of the patellofemoral joint. Level IV, diagnostic case-control study.

Medial patellofemoral ligament injury patterns and associated pathology in lateral patella dislocation: an MRI study

BackgroundLateral Patella dislocations are common injuries seen in the active and young adult populations. Our study focus was to evaluate medial patellofemoral ligament (MPFL) injury patterns and associated knee pathology using Magnetic Resonance Imaging studies.MethodsMRI studies taken at one imaging site between January, 2007 to January, 2008 with the final diagnosis of patella dislocation were screened for this study. Of the 324 cases that were found, 195 patients with lateral patellar dislocation traumatic enough to cause bone bruises on the lateral femoral trochlea and the medial facet of the patella were selected for this study. The MRI images were reviewed by three independent observers for location and type of MPFL injury, osteochondral defects, loose bodies, MCL and meniscus tears. The data was analyzed as a single cohort and by gender.ResultsThis study consisted of 127 males and 68 females; mean age of 23 yrs. Tear of the MPFL at the patellar attachment occurred in 93/195 knees (47%), at the femoral attachment in 50/195 knees (26%), and at both the femoral and patella attachment sites in 26/195 knees (13%). Attenuation of the MPFL without rupture occurred in 26/195 knees (13%). Associated findings included loose bodies in 23/195 (13%), meniscus tears 41/195 (21%), patella avulsion/fracture in 14/195 (7%), medial collateral ligament sprains/tears in 37/195 (19%) and osteochondral lesions in 96/195 knees (49%). Statistical analysis showed females had significantly more associated meniscus tears than the males (27% vs. 17%, p = 0.04). Although not statistically significant, osteochondral lesions were seen more in male patients with acute patella dislocation (52% vs. 42%, p = 0.08).ConclusionPatients who present with lateral patella dislocation with the classic bone bruise pattern seen on MRI will likely rupture the MPFL at the patellar side. Females are more likely to have an associated meniscal tear than males; however, more males have underlying osteochondral lesions. Given the high percentage of associated pathology, we recommend a MRI of the knee in all patients who present with acute patella dislocation.

Femoral Avulsion of the Medial Patellofemoral Ligament after Primary Traumatic Patellar Dislocation Predicts Subsequent Instability in Men

Background The clinical relevance of medial patellofemoral ligament (MPFL) injury location in primary patellar dislocation has not been studied. Hypothesis Prognosis after primary traumatic patellar dislocation may vary by MPFL injury location. Study Design Cohort study; Level of evidence, 3. Methods The initial magnetic resonance imaging (MRI) findings in 53 patients with identical nonoperative management were retrospectively analyzed for medial restraint injuries. The MPFL injury sites were classified as follows: femoral, midsubstance, and patellar. Magnetic resonance imaging was used to assess initial and control articular cartilage lesions in the patellofemoral joint. After a mean follow-up of 7 years, 42 patients were evaluated for redislocations, subjective symptoms, and functional limitations. Results Based on the initial MRIs, MPFL rupture was classified as femoral in 35 patients, midsubstance in 11, and patellar in 7. At follow-up, 15 patients reported an unstable patella (13 femoral, 1 patellar, 1 midsubstance; P =. 01) and 9 reported patellar redislocations (8 femoral, 1 midsubstance; P =. 05). The proportion of patients who regained their preinjury activity level was significantly smaller among those with femoral MPFL injury than among those with midsubstance or patellar MPFL injury (P =. 05). The median Kujala score was as follows: 90 for femoral, 91 for patellar, and 96 for midsubstance (P =. 76). Control MRI showed full-thickness patellofemoral cartilage lesions in 50% of the patients, unrelated to MPFL injury location. Conclusion An MPFL avulsion at the femoral attachment in primary traumatic patellar dislocations predicts subsequent patellar instability. The authors suggest that MPFL injury location be taken into account when planning treatment of primary traumatic patellar dislocation.

Reply to Letter to Editor: Ligament Reconstruction Versus Distal Realignment for Patellar Dislocation

We welcome Dr. Vavalle’s comments on our study [2]. Dr. Vavalle posed two important questions regarding our study, including the indications for medial patellofemoral ligament (MPFL) reconstruction and assessment of patellofemoral tracking in regard to optimal surgical correction of patellar instability and prevention of degenerative changes. These questions probably could be justifiably raised to any study evaluating surgical management of patellar instability. Based on recent studies, MPFL reconstruction has gained acceptance over other soft tissue approaches to stabilize the patella. As the MPFL is the primary soft tissue restraint against lateral displacement of the patella, MPFL injury is best addressed by repair or reconstruction of the ligament. However, patellofemoral abnormalities, such as lateral retinacular tightness, increased tibial tubercle-trochlear groove distance, patella alta, and trochlea dysplasia, sometimes occur, as mentioned by Dr. Vavalle. We agree with his comments that additional surgical procedures probably sometimes should be combined with the MPFL reconstruction if the osseous architecture of the patellofemoral joint is substantially abnormal. Perhaps the most often needed additional procedure is distal realignment in the case of excess tibial tubercle-trochlear groove distance. We have not performed trochleoplasties, and we believe lateral retinacular release rarely is needed and should be performed only in cases in which the patella cannot be medialized into the trochlea without substantial tightness of the lateral structures. Patellar instability during childhood or adolescence, without a major initial external traumatic event, usually is involved with these abnormalities predisposing chronic instability. Given the fact that our study group involved patients with traumatic etiology of primary patellar dislocation, these bony abnormalities were found relatively infrequently, despite patella alta. We compared soft tissue stabilizations without additional surgical procedures, while trying to provide insight into an essential comparison of soft tissue surgical procedures. Again, we agree with Dr. Vavalle’s opinion that a surgical technique can prevent degenerative changes, especially when it improves patellofemoral tracking. Of the indices Dr. Vavalle mentioned, we measured lateral patellofemoral angle postoperatively but not congruence angle. Because we have found some of the patellofemoral radiographic indices relatively unreliable, we decided to describe only some of them. Regarding the assessment of congruence angle, our experience suggests it is readily affected by the knee extension-flexion position and muscle tension during the radiographs and, perhaps most importantly, the engagement position of the patella into the trochlea. The axial radiographic indices seem to be portrayed somewhat differently with the Merchant view, Laurin view, or routine knee MRI, because of the anatomic features of the trochlea and the interplay with existing muscle tension and soft tissue restraints [1]. Trochlear cartilage shape assessed on MRI might not be aligned with the bony shape of the trochlea on a Merchant view. In addition, a high-riding patella easily predisposes to radiographic incongruence, because patellar engagement may require even deeper flexion than 45°. We believe the potential observation errors in assessment of these indices may result in poor reliability of the values and questionable clinical validity. A fair conclusion might be MPFL reconstruction should control patellar tracking in a way that simulates the anatomic preinjury patellofemoral kinematics. We appreciate Dr. Vavalle’s comments and thank him for his valuable views on this topic.

Extensor Mechanism Injuries in Tibiofemoral Dislocations

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. 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. 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%). 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.

Incidence and Risk Factors of Acute Traumatic Primary Patellar Dislocation

The purpose of this study was to investigate incidence, nature, and risk factors of primary traumatic patellar dislocations. We identified acute first-time traumatic patellar dislocations from a national hospital discharge register. Patients with previous patellar dislocations, subluxations, or knee traumas were excluded. The sample consisted of 128,714 Finnish male conscripts (median age 20). Background risk factor data were obtained from a Finnish conscript service database. The dislocators were observed during their service period for a short-term outcome. From the 128,714 male conscripts, 278 had patellar dislocations, and 72 were classified as having sustained first-time traumatic patellar dislocations. The 128,436 nondislocators served as a control group. The incidence of acute traumatic primary patellar dislocations among male conscripts was 77.4 (95% CI: 61.1-96.8) per 100,000 persons per year. The male patients with traumatic primary patellar dislocations were taller (P = 0.03) and weighed more (P = 0.02) than the controls. Hemarthrosis was present in all patients, and when MRI or open surgery was performed, medial retinacular disruption and medial patellofemoral ligament (MPFL) injury were identified. Patients' return to military service was unrelated to the choice of treatment. Primary patellar dislocation is not a negligible cause of morbidity among young male adults. It can be concluded that hemarthrosis and MPFL rupture are the definite signs of an acute traumatic primary patellar dislocation. Height and weight were significant risk factors, whereas poor physical performance was not associated with primary patellar dislocation.

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

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

Augmented repair of avulsion-tear type medial patellofemoral ligament injury in acute patellar dislocation

This study investigated the results of augmented repair for avulsion-tear type medial patellofemoral ligament (MPFL) injury performed on a total of five knees with initial acute lateral patellar dislocation. Augmented repair was performed using a medial retinaculum slip on all five knees. The average follow-up was 5.9 years. The results were evaluated with the Insall, Aglietti, and Tria grading system. Three knees were classified as excellent, one knee as good, and one knee as fair. The mean Kujala score at follow-up was 97.6 points. Augmented repair of the injured MPFL for avulsion-type MPFL injury may be considered as one good option to prevent subsequent dislocation and subluxation.

Correlation of MR imaging findings and open exploration of medial patellofemoral ligament injuries in acute patellar dislocations

The purpose of this investigation was to correlate magnetic resonance (MR) images of medial patellofemoral ligament (MPFL) injuries with gross macroscopic findings. Twenty-seven knees with MPFL injury following an initial patellar dislocation were examined using axial proton-density and T2-weighted fast spin-echo MR imaging. MR findings were subsequently correlated with open exploration. MPFL injury was observed in 26 (96%) of the 27 knees. From the MR images, discontinuity, irregularity and/or high-signal intensity changes anterior to the femoral attachment were seen in 13 (82%) of the 16 knees with substantial-tear type injuries of the MPFL. In 8 (80%) of the 10 knees with avulsion-tear type injuries, detachment of the MPFL from the femoral attachment, accompanied with or without high-signal intensity changes, was confirmed. MPFL injury types could be accurately diagnosed on 21 (81%) out of 26 knees using MR imaging. MR imaging was an acceptable method in diagnosing MPFL injury types.

Medial patellofemoral ligament injury following acute transient dislocation of the patella: MR findings with surgical correlation in 14 patients.

The purpose of this study was to determine the accuracy of MRI in determining both the extent and the location of injury to the medial patellofemoral ligament (MPFL). MR findings were compared to the surgical results of 14 consecutive patients who experienced transient patellar dislocation. Two musculoskeletal radiologists, blinded to the surgical results, retrospectively reviewed the MR studies, and a consensus reading was obtained. Surgery demonstrated complete disruption of the MPFL in 7 of 14 patients (50%), with stretching or partial tearing of the MPFL in the remaining 7 (50%) patients. MRI was 85% sensitive and 70% accurate in detecting MPFL disruption. Vastus medialis obliquus muscle elevation was present in 12 of 14 (85%). MRI accurately depicts both the extent and the location of MPFL injury following transient patellar dislocation and can therefore play a significant role in directing surgical management of these patients.

Classification of lesions of the medial patello-femoral ligament in patellar dislocation.

The remnants of the medial patello-femoral ligament (MPFL) of 67 knees, 18 with acute patellar dislocation and 49 with chronic patellar dislocation, were studied. The MPFL injuries of the acute cases were categorised into 2 groups: an avulsion tear type and a substantial tear type. The chronic cases were put into 3 groups: those with loose femoral attachment (9 knees), those with scar tissue formation or abnormal scar branch formation (29 knees), and those with no evidence or continuity of the ligament (absent type) (11 knees). It is concluded that incompetence of the medial patello-femoral ligament is a major factor in the occurrence of recurrent patellar dislocation and/or an unstable patella following an acute patellar dislocation.

Lymphopaenia in elderly in-patients

<h3></h3> <b>Background:</b> Patella instability and medial patellofemoral ligament (MPFL) injury are frequently encountered in pediatric patients. MPFL reconstruction is often chosen to treat this condition with good results; however, no consensus has been reached about which graft or technique to use. The purpose of this study was to evaluate the differences in graft survivorship, clinical outcomes (assessed with Kujala scores), and cost between autograft and allograft usage in MPFL reconstruction in pediatric patients. <b>Methods:</b> In this retrospective review of patients who underwent MPFL reconstruction between 2012-2015, autograft gracilis tendon was used for Group 1, and allograft gracilis tendon was used for Group 2. Outcomes were graft survivorship, postoperative Kujala scores, operative time, costs, graft size, and tibial tubercle–trochlear groove distance. <b>Results:</b> Fifty-six patients were included in this study, 21 in Group 1 and 35 in Group 2. No differences in age, sex, or chronicity were seen between the groups. Patients in Group 1 had longer operative times (134.5 minutes vs 97.3 minutes, <i>P=</i>0.0002), higher rates of graft failure (28.6% vs 0%, <i>P</i>=0.0037), and lower Kujala scores (80.3 vs 92.1, <i>P</i>=0.0032) compared to Group 2. All graft failures occurred in patients with chronic patella dislocations and occurred an average of 13.8 months postoperatively. Overall, autograft was costlier than allograft because of the cost of reoperation. <b>Conclusion:</b> This study supports the use of allograft for chronic patellar instability because of improved graft survivorship and clinical outcome scores, as well as the lower cost and reoperation rate.