Recurrent Lateral Dislocation Of Patella Research Articles

The accuracy of multiple regression models for predicting the individual risk of recurrent lateral patellar dislocation

BackgroundRecurrent lateral patellar dislocation (RLPD) poses a significant threat to patients’ quality of life due to knee pain, patellofemoral cartilage damage, and potential traumatic arthritis. Predictive scoring systems have been developed to assess the risk of RLPD; however, their relative accuracy remains uncertain.PurposeTo investigate the accuracy of the multiple regression models to predict the individual risk of recurrent LPD.MethodsThe Patellar Instability probability calculator (PIP), Recurrent Instability of the Patella Score (RIP), and Patellar Instability Severity Score (PIS) scoring rules were measured in 171 patients with a history of patellar dislocation and 171 healthy individuals. Three prediction models were calculated based on the data to predict the risk of recurrent lateral patellar dislocation. The inter-observer and intra-observer reliability of each measurement parameter was evaluated. The predictive capacity of the three-prediction model was investigated using the receiver operating characteristic curve.ResultsIn the case group of 171 patients, PIS accurately predicted recurrent lateral Patella dislocation in 143 patients. RIP was 96, and PIP was 83. The positive predictive values were 92.9%, 64%, and 68% respectively. In the control group of 171 patients, the PIS was validated in 160 patients who would not experience dislocations. RIP was 117, and PIP was 50. The negative predictive values were 85.1%, 60.9%, and 36.2%, respectively. The area under the curve score for the PIS was 0.866, and the RIP was 0.673. the PIP was 0.678.ConclusionRIP and PIP did not work to predict LPD. PIS can accurately predict recurrent lateral patellar dislocation. It can aid doctors in making treatment decisions.Level of evidenceLevel III, retrospective comparative study.

Persistent J-Sign Following Distalization with Correction of Patellar Height: A Descriptive study reviewing anatomic factors (195)

Objectives:The anatomic factors associated with a J-sign (patella dislocation in extension) are debated and likely multi-factorial. With trochlear shape and patella height playing a role. The goal of distalization of the tibial tubercle (dTTO) is normalization of patella height to improve patellar stabilization by earlier trochlear groove engagement. dTTO is felt to diminish or remove the J-sign by ‘by-passing’ the supra-trochlear bump, thus avoiding the need for a trochleoplasty in addition to a dTTO. The objective is to determine if a persistent J-sign after surgical patellar stabilization and adequate patellar height restoration is due to additional anatomic variances that were not surgically addressed.Methods:A retrospective chart review of 89 consecutive patients who were treated by a single surgeon for recurrent lateral patella dislocation with medial patellofemoral ligament reconstruction (MPFL-R) and dTTO was undertaken. 63 patients were identified with a pre-operative J-sign and formed the study sample. 40 of these patients had no J-sign post-operatively and 23 patients had a persistent postoperative J-sign. All patients had radiographic measurements made for patella alta (caton-deschamps index [CD]), and magnetic resonance imaging measurements of trochlear depth, sulcus angle, as well as the individual components for measuring trochlear depth (medial, central, and lateral height).Results:The average age of patients at time of surgery was 21 years old (range,13-45). Females were 74% of the population. Average BMI was 26 (17-44) and follow-up averaged 16 months. Table 1 demonstrates the between group differences for the statistically significant variables. These included trochlear depth, and lateral-central difference (via components of trochlear depth calculation) (fig 1). If the patient had lateral condylar height < medial condylar height, a J -sign persisted (4 patients). When the post op C/D >/= 1.2, 5/6 (83%) patients had a persistent j-sign. There were 5 re-dislocations in this population: 2/23 (13%) with a persistent J-sign and 3/40 (8%) without. The KOOS was available for all patients at a minimum of 3 months (Table 2). There was no statistically significant domain that demonstrated a difference between the 2 groups. In both groups, the domains with the lowest scores were quality of life, sports, and symptoms.Conclusions:Dysplastic trochlea that have a small lateral-central difference (<2mm), a shallower trochlear depth, or a lateral condylar height less than the medial condylar height, are more likely to result in a persistent J-sign. In the setting of these dysplastic trochleas, consideration should be given to address trochlear anatomy at the same time as addressing patella height normalization.In the presence of a J-sign, patella height should be normalized to CD < 1.1 to reduce the likelihood of a persistent J-Sign. Post-Op KOOS scores suggest the persistent J-sign does not impact the functional recovery in these patients. In our cohort, there was no increased risk of re-dislocation with a persistent J-Sign.

Morphological study of the vastus medialis oblique in recurrent patellar dislocation based on magnetic resonance images

BackgroundTo investigate the morphological parameters of the vastus medialis obliquus (VMO) muscle and delineate its importance in the maintenance of patellofemoral joint stability.MethodsThe magnetic resonance imaging data of seventy-five knees (fifty-four patients) with recurrent lateral patella dislocation (LPD) and seventy-five knees (seventy patients) without recurrent LPD were retrospectively analysed. Five morphological parameters related to the VMO (elevation in the sagittal plane and coronal plane, craniocaudal extent, muscle-fibre angulation, cross-sectional area ratio) and two patella tilt parameters (patella tilt angle, bisect offset ratio) were measured in MR images. The independent-samples t test or chi-square test was used for statistical comparisons.ResultsThe mean ages of the patients in the recurrent LPD group and control group were 22.1 ± 9.9 years and 24.0 ± 6.5 years, respectively. Eighteen out of seventy-five (24%) patients MRI showed VMO injuries. Compared with the control group, the patients with recurrent LPD showed significantly higher sagittal VMO elevation (10.4 ± 2.3 mm vs. 4.1 ± 1.9 mm), coronal VMO elevation (15.9 ± 5.7 mm vs. 3.9 ± 3.7 mm), muscle-fibre angulation (35.4 ± 8.0° vs. 27.9 ± 6.3°), patella tilt angle (25.9 ± 10.7° vs. 9.1 ± 5.2°), and bisect offset ratio values (0.9 ± 0.3 vs. 0.5 ± 0.1) and significantly lower craniocaudal extent (13.7 ± 5.3 mm vs. 16.7 ± 5.1 mm) and cross-sectional area ratio values (0.05 ± 0.02 vs. 0.07 ± 0.02).ConclusionsThe results showed that abnormalities in the VMO and patella tilt were clearly present in recurrent LPD patients compared with normal people.

Recurrent lateral patella dislocation affects knee function as much as ACL deficiency \u2013 however patients wait five times longer for treatment

BackgroundSurgical treatment of young patients with recurrent lateral patella dislocation (RLDP) is often recommended because of loss of knee function that compromises their level of activity or even their daily life functioning. This situation is comparable to young patients with an anterior cruciate ligament (ACL) rupture. The purpose of this study was therefore to explore the time from injury to surgery and the pre-operative symptoms and knee function of young RLPD patients scheduled for stabilizing surgery and compare this group to age and sex-matched ACL-deficient patients.MethodForty-seven patients with unilateral RLPD listed for isolated medial patellofemoral ligament reconstruction were included in the study (RLPD-group). This group was compared to an age, sex and BMI matched ACL patient group obtained from the Norwegian knee ligament registry (ACL-group) for the following outcome measures: the knee injury and osteoarthritis outcome score (KOOS) assessed on the day of surgery and time from injury to surgery.ResultsThe RLPD-group scored significantly lower than the ACL-group for the three KOOS subscales “Pain” (73.6 vs. 79.8, p < 0.05), “Symptoms” (71.7 vs. 79.3, p < 0.05) and “ADL” (84.7 vs 89.5, p < 0.05). The lowest KOOS values were found for Sports/Recreation (53.5 vs. 51.3, p = 0.65) and Quality of life (37.6 vs. 36.7, p = 0.81). The average time from primary injury to surgery was 6 months for the ACL group and 31 months for the RLPD group.ConclusionRLPD affected knee function as much as ACL deficiency, and was associated with more pain. Still the RLDP patients waited on average 5 times longer for surgery.Trial registrationThe patients with RLPD consisted of patients who were examined for possible recruitment for a concurrent prospective randomized controlled trial comparing conservative treatment and isolated surgical medial patellofemoral ligament (MPFL) reconstruction (Clinical trials no: NCT02263807, October 2014).

Distalization Of Tibial Tubercle For Patella Stabilization: Does Length Of Distalization Or Residual Patella Alta Effect Outcome?

Objectives: Distalization of the tibial tubercle (DTT) is a surgical procedure to help stabilize the patella when patella alta is present. The purpose of this study is to: evaluate the accuracy of our operative intervention (i.e. how often is patella height normalization achieved). correlate post-operative (residual) patella alta with recurrent patellar instability correlate the mm of distal displacement with negative outcomes Methods: Data was collected retrospectively on consecutive patients who underwent DTT as part of their surgical procedure for recurrent lateral patella dislocation. All patients had concurrent medial patella ligament reconstruction (MPFLR), performed by a single surgeon between 2009-2015. Data collected included demographics, pre-and post-operative imaging measurements related to patella alta and trochlear dysplasia on MRI and plain radiographs, recurrent lateral patella dislocations, and complications including fracture and knee arthrofibrosis. Surgical planning including the assessment of the Caton-Deschamps index (CD) on sagittal radiographic imaging. The surgical goal was to have a final CD between 1.0 -1.2, or a maximum distance moved of 15 mm in cases of severe patella alta. When CD was within normal limits due to patellar anatomy, we used as a proxy the patellar-trochlear index (PTI), aiming for a PTI of 25% judged intra-operatively. Results: 89 patients underwent DTT over a 7-year period. There were 21 (24%) males/68 (76%) females. Mean (range): age 21 (13-45), BMI 25.8 (17-44.6). Pre-op imaging measurements were: IS ratio 1.5 (1.18-2.06), CD ratio 1.4 (1.05 -1.93), lateral patella tilt 24.7º (1º-53º), TT-TG 18.6 mm (8-28), sulcus angle 158º (123-180), PTI 29% (5-70). Post-operative mean CD was 1.09 (0.92 -1.67). The amount of distalization averaged 9.8 (range 4 to 15). 13 patients had residual patella alta (CD&gt;1.2). One patient with residual patella alta re-dislocated (CD=1.25). The most extreme residual patella alta (1.67) had a pre-op CD of 1.97 and was distalized 15 mm. There was no patellar baja. 6 patients (6%) had frank recurrent patellar dislocation; postoperative patella height in this group averaged 1.11 (1.02 -1.25), indicating that re-dislocation was not due to residual patella alta. Tibia fracture (4%) was not related to mm of distalization; mean (10) /range 8-15 mm. Arthrofibrosis requiring manipulation was needed in 11 patients (13%) whose mean distalization was 11.8 mm (9-15 mm). This distance was significantly different (p=0.009) from those not requiring manipulation. Conclusion: Distalization of TT leads to a high rate of normalization of patellar height measurements, with 94% patella stabilization. Residual patella alta was not associated with an increased risk of recurrence (p=0.57). Distalizing the tibial tubercle up to 15 mm did not increase fracture risk, however there was an increase in arthrofibrosis requiring manipulation.

Displacing lateral meniscus masquerading as patella dislocation

To alert the treating clinician to an uncommon knee meniscal condition that often masquerades as a more common patella condition. Retrospective chart review of a series of cases was undertaken. A series of 12 knees in 11 patients were referred to an orthopaedic surgeon with a diagnosis of recurrent lateral patella dislocation. Three knees had undergone patella realignment surgery with continuance of symptoms. Eight patients had prior magnetic resonance images read as no meniscal pathology and no acute patella/patella retinacular injury. All patients presented for a consult with a similar history. Under anaesthesia, all knees had a stable patella as judged by physical examination. At the time of surgery, six patients had a frank tear in the lateral meniscus, all of which were readily displaceable. Six knees showed a displaceable lateral meniscus with attenuation but not a visible frank tear. Ten menisci were treated with repair, and two knees underwent partial lateral meniscectomies. Patient follow-up of minimally 18months revealed no further episodes of "knee-cap dislocation" or symptoms of catching and locking. The clinician treating a patient with a history of a knee locking in flexion should have a high index of suspicion for a lateral meniscus tear or an unstable hypermobile lateral meniscus, despite patient report of perceived patella movement. History of symptoms occurring in knee flexion and attention to patella physical examination should be key factors in this diagnostic conundrum. Retrospective chart review, Level IV.

Influence of arthroscopic lateral release on functional recovery in adolescents with recurrent patellar dislocation

The aim of this study is to prove the influence of the arthroscopic lateral release on functional recovery in adolescents with recurrent lateral dislocation of patella. From 2006 to 2009, arthroscopic release of the lateral retinaculum was done on 27 adolescent patients (24 women, 3 men) and 33 knees (in 6 patients on both knees). All of them were active in different sports. The severity of patellar subluxation and dislocation was analysed on X-ray; the Q angle, congruence angle, sulcus angle, patellofemoral angle and height ratio were measured. Functional scores (Lysholm, Kujala, Tegner) were measured preoperatively and postoperatively. The average duration of clinical and X-ray follow-up was 4.5years (range 3-6years). The mean age of the patients was 14.56years (range 11-18years). There was an average of 4.16 dislocations (range 2-28 dislocations) before surgery. The mean Lysholm score improved from 64 to 95 (p=0.0002), and the mean Kujala score improved from 66 to 94 (p<0.0001). Congruence angle and lateral patellofemoral angle improved but without any significant differences. Arthroscopic lateral release successfully treats recurrent patellar dislocations in adolescents, influences functional recovery and improves knee function.