Medial Patellar Instability: A Systematic Review of the Literature of Outcomes After Surgical Treatment

Patient-reported outcome scores following patellar instability surgery-high prevalence does not equal high responsiveness: a systematic review

PURPOSE

The purpose of this study was to determine the utilization and responsiveness of common patient-reported outcomes (PROs) in patients undergoing surgery for patellar instability.

METHODS

Using PRISMA guidelines, a systematic review of studies reporting outcomes following surgical intervention for patellar instability was conducted using Pubmed, Cochrane, OVID Medline, and Google Scholar. Subgroup analysis of articles reporting at least two PROs with baseline and follow-up data were used to evaluate responsiveness of instruments using relative efficiency and effect size.

RESULTS

From the search, 2,848 unique articles were found, of which 178 were included in final analysis (7,122 patients, mean age 22.6, 63.6% female). The most commonly used PRO was the Kujala score (79.2%), followed by the Lysholm (34.8%), and Tegner (30.9%). Seventy-nine articles were eligible for subgroup analysis. The Kujala had a higher relative efficiency than ten of the 14 instruments to which it was compared but had lower relative efficiency compared to the IKDC and Lysholm scores. The Banff Patella Instability Instrument (BPII) and the Norwich score, condition-specific tools, were unable to be fully assessed due to rarity of use and lack of comparisons.

CONCLUSION

The hypothesis that the Kujala score is the most commonly used PRO for patellar instability, although other instruments offer greater efficiency was supported by our results. The IKDC and Lysholm scores had similar effect sizes but higher relative efficiencies than the Kujala, thus suggesting better responsiveness. This analysis adds useful information for surgeons on the effectiveness of the most common PRO's for evaluating patellofemoral instability outcomes.

LEVEL OF EVIDENCE

Level III.

Bilateral Medial and Lateral Patellofemoral Ligament Reconstruction in a Patient with Hypermobility Type Ehlers-Danlos Syndrome: A Case Report

CASE

Medial patellar instability (MPI) is a known sequela of previous lateral retinacular release. Literature on surgical intervention is scarce. We present a case of a 35-year-old woman with hypermobility type Ehlers-Danlos syndrome, with bilateral iatrogenic MPI (IMPI) and lateral patellar instability. This condition led to a marked decrease in quality of life, 10/10 persistent pain, and frequent dislocation events. She was successfully treated surgically, and at 2 years had 0/10 pain and no further dislocations.

CONCLUSIONS

Our technique for medial and lateral patellofemoral ligament reconstruction is a viable intervention for patients with IMPI, even in the setting of underlying collagen disorder.

Medial Patellofemoral Ligament Reconstruction: A Comparison of Single-Bundle Transpatellar Tunnel and Double-Anchor Anatomic Techniques for the Treatment of Recurrent Lateral Patellar Dislocation in Adults

PURPOSE

To compare the stability and clinical outcomes of 2 medial patellofemoral ligament reconstruction (MPFLR) techniques for the treatment of recurrent lateral patellar dislocation in adults.

METHODS

Ninety-one patients with recurrent patellar dislocation were randomly divided into 2 groups, undergoing either the traditional single-bundle transpatellar tunnel technique (group A) or the double-anchor anatomic reconstruction technique (group B). Preoperatively and at follow-up, the patellar position and rotation were evaluated by computed tomography with the congruence angle, lateral patellar angle, patellar tilt angle, and lateral patellar translation; the subjective symptoms and functional outcomes were evaluated with Kujala, Lysholm, Tegner, and International Knee Documentation Committee subjective scores. Clinical examinations were also performed, and redislocations or episodes of instability were recorded.

RESULTS

Patients were followed up for a mean period of 41.11 ± 7.40 months (range, 29-62 months). At the final point, no recurrent patellar dislocations occurred, except in 4 patients with instability symptoms in group A; however, no significant difference between the 2 groups was seen (χ² = 2.503, P = .114). The measurement results from computed tomography decreased significantly to the normal range, and no significant difference was found between the 2 groups except for the lesser patellar tilt angle in group B (t = 2.175, P = .030). The clinical examination improved significantly, no patient exhibited a positive apprehension test in either group, and the number of patients with abnormal lateral patellar translation grade and firm end point showed no statistically significant differences between the 2 groups (P > .05). All score systems significantly improved with no significant difference between the 2 groups except for the higher Kujala score (t = -40.635, P = .001) and International Knee Documentation Committee score (t = -33.823, P = .003) in group B.

CONCLUSIONS

Both MPFLR techniques achieved good results in the treatment of patellar dislocation. Compared with the single-bundle transpatellar tunnel technique, the double-anchor anatomic MPFLR technique may be more effective with a more congruous patellofemoral joint and better knee function.

LEVEL OF EVIDENCE

Level II, prospective comparative study.