Many studies have reported satisfactory clinical outcomes and low redislocation rates after reconstruction of the medial patellofemoral ligament (MPFL) for the treatment of lateral patellar instability. Despite uncorrected severe trochlear dysplasia (Dejour type B to D) being acknowledged as a major reason for less favourable clinical outcomes and a higher incidence of patellar redislocations after an isolated MPFL reconstruction, the evidence for a deepening trochleoplasty procedure remains scarce in the current literature. The hypothesis of this systematic review and meta-analysis was that a deepening trochleoplasty in combination with an a la carte extensor apparatus balancing procedure provides lower redislocation rates and superior clinical outcomes than isolated MPFL reconstruction in patients with lateral patellar instability caused by severe trochlear dysplasia.
A systematic review of the literature was conducted using specific inclusion and exclusion criteria for clinical studies reporting index operations (trochleoplasty and MPFL reconstruction) for the treatment of patellar instability caused by severe trochlear dysplasia. The Kujala score was analysed as the primary clinical outcome parameter in a random effects meta-analysis.
Ten uncontrolled studies with a total of 407 knees (374 patients) were included in this analysis. The MPFL group comprised 4 studies with a total of 221 knees (210 patients), and the trochleoplasty group comprised 6 studies with a total of 186 knees (164 patients). The mean preoperative Kujala score ranged between 50.4 and 70.5 in the MPFL group and between 44.8 and 75.1 in the trochleoplasty group. The pooled Kujala score increased significantly by 26.4 (95% CI 21.4, 31.3; P < 0.00001) points in the MPFL group and by 26.2 (95% CI 19.8, 32.7; P < 0.00001) points in the trochleoplasty group. The post-operative patellar redislocation/subluxation rate was 7% in the MPFL group and 2.1% in the trochleoplasty group.
This analysis found significant post-operative improvements in patient-reported outcomes for patients undergoing both an MPFL reconstruction and in those undergoing a trochleoplasty plus an individual extensor apparatus balancing procedure when assessed using the Kujala score. The likelihood of preventing the patella from subsequent post-operative redislocation/subluxation was, however, greater in patients who underwent trochleoplasty plus extensor balancing.
Level of evidence
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This study was performed at the University Medical Center Göttingen, Göttingen, Germany.
PB contributed to conception and design, analysis and interpretation of data, drafting the manuscript, and final approval; SR helped in acquisition of data, analysis and interpretation of data, and final approval; NH contributed to acquisition and interpretation of data and final approval; JDE contributed to acquisition and interpretation of data and final approval; KK helped in acquisition and interpretation of data and final approval; DD contributed to acquisition and interpretation of data and final approval; MN contributed to acquisition and interpretation of data and final approval; IJB helped in acquisition and interpretation of data and final approval; DL helped in acquisition and interpretation of data and final approval; MH contributed to acquisition of data, analysis and interpretation of data, and final approval; and TF helped in analysis and interpretation of data and final approval.
Conflict of interest
The authors declare that they have no competing interests.
For this type of study (systematic review and meta-analysis) formal consent is not required.
This study received no funding.
This article does not contain any studies with human participants performed by any of the authors.
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Balcarek, P., Rehn, S., Howells, N.R. et al. Results of medial patellofemoral ligament reconstruction compared with trochleoplasty plus individual extensor apparatus balancing in patellar instability caused by severe trochlear dysplasia: a systematic review and meta-analysis. Knee Surg Sports Traumatol Arthrosc 25, 3869–3877 (2017). https://doi.org/10.1007/s00167-016-4365-x
- Patellar instability
- Trochlear dysplasia
- Medial patellofemoral ligament
- MPFL reconstruction