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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. 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. 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. 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. IV.

This report presents two cases of high-level athletes with bilateral patellar dislocations who were able to return to their preinjury level of activity after bilateral medial patellofemoral ligament (MPFL) reconstruction, without any major complications. Patient 1 was a 19-year-old male volleyball player for a top-level college volleyball team, and patient 2 was a 24-year-old woman who was a member of a national-level adult softball team. MPFL reconstruction could be an effective treatment for bilateral patellar dislocation in high-level athletes. Level of evidence V.

The purpose of this study was to identify the risk factors for recurrent lateral patellar dislocations and to incorporate those factors into a patellar instability severity score.Sixty-one patients [male/female 35/26; median age 19 years (range 9-51 years)] formed the study group for this investigation. Within the study group, 40 patients experienced a patellar redislocation within 24 months after the primary dislocation, whereas 21 patients, who were assessed after a median follow-up of 37 months (range 24-60 months), had not experienced a subsequent episode of lateral patellar instability. In all patients, age at the time of the primary dislocation, gender, the affected body side, body mass index, bilateral instability, physical activity according to Baecke's questionnaire, the grade of trochlear dysplasia, patellar height, tibial tuberosity-trochlear groove (TT-TG) distance, and patellar tilt were assessed. The odds ratio (OR) of each factor with regard to the patellar redislocation was calculated using contingency tables. Based on these data, a "patellar instability severity score" was calculated.The patellar instability severity score has six factors: age, bilateral instability, the severity of trochlear dysplasia, patella alta, TT-TG distance, and patellar tilt; the total possible score is seven. Reapplying this score to the study population revealed a median score of 4 points (range 2-7) for those patients with an early episode of patellar redislocation and a median score of 3 points (range 1-6) for those without a redislocation (p=0.0004). The OR for recurrent dislocations was 4.88 (95% CI 1.57-15.17) for the patients who scored 4 or more points when compared with the patients who scored 3 or fewer points (p=0.0064).Based on the individual patient data, the patellar instability severity score allows an initial risk assessment for experiencing a recurrent patellar dislocation and might help differentiate between responders and non-responders to conservative treatment after primary lateral patellar instability.Case-control study, Level III.

The objective of this study was to evaluate the mid-term results of a new technique for the arthroscopic repair of MPFL after an acute patellar dislocation (APD).The series included 17 patients (11 men and 6 women) with a first episode of acute patellar dislocation; treated over a period of 6 years. Re-dislocation, subjective symptoms and functional limitations were evaluated at an average follow-up of 2.2 years (1-5.5). The patients were evaluated with the Lysholm and the Kujala scoring systems.At follow-up, no re-dislocation was reported. Only one patient referred an episode of patellar instability, without a distinct dislocation. The postoperative median Lysholm score was 90 (72-100). The median Kujala score was 92 (75-100). Fourteen out of 17 patients were able to return to sports at the same level as before.When the MPFL is avulsed from the patella, the proposed technique has the advantage of restoring tension of the ligament through reattachment at the patellar border with two trans-patellar sutures. The full-arthroscopic approach has the advantage of being less invasive and having a shorter recovery time.