Effects of Lateral Patellar Retinaculum Release for Recurrent Patella Dislocation: A Prospective Study

Figures & data

Figure 1 Consort diagram of the study.

Abbreviation: RPD, recurrent patella dislocation.

Figure 2 Workflow of necessary steps in this study. Randomization was performed and each patient was numbered. Patients with odd numbers were allocated to isolated MPFL reconstruction (Group I) and others were allocated to MPFL reconstruction combined with LPR release (Group II). Postoperative assessments including CT measurements and knee function were performed.

Abbreviations: CT, computed tomography; MPFL, medial patellofemoral ligaments; LPR, lateral patellar retinaculum.

Figure 3 The schedule of MPFL reconstruction with autografts: femoral and patellar bone tunnels.

Abbreviation: MPFL, medial patellofemoral ligaments.

Figure 4 The schedule of LPR release.

Abbreviation: LPR, lateral patellar retinaculum.

Table 1 Demographic Characteristics of the Population of the Study

Variables	Group I (n=45)	Group II (n=42)	P value
Age (years)	24.9 ± 7.2	27.1 ± 8.9	0.207
Males/females	17/28	20/22	0.354
BMI	22 ± 7.9	24 ± 7.2	0.222
Left side/right side	21/24	23/19	0.450
Duration of dislocation (months)	18.1 ± 6.7	19.8 ± 7.2	0.257
Number of dislocations	4.1 ± 2.1	3.7 ± 1.9	0.355

Notes: Group I: isolated MPFL reconstruction; Group II: MPFL reconstruction combined with LPR release.

Abbreviations: BMI, body mass index; MPFL, medial patellofemoral ligament; LPR, lateral patellar retinaculum.

Table 2 Comparisons of Preoperative Patella Associated Measurements and Knee Function Between the Two Groups

Variables	Group I (n=45)	Group II (n=42)	P value
Congruence angle	31.87 ± 4.23	32.64 ± 3.91	0.381
Patellar tilt angle	13.29 ± 2.17	13.47 ± 2.23	0.704
Lateral patellofemoral angle	−2.6 ± 3.8	−2.4 ± 4.7	0.827
TT-TG distance (mm)	16.7 ± 2.9	17.4 ± 3.2	0.288
Lysholm score	55.4 ± 5.1	56.7 ± 6.8	0.314
IKDC score	41.2 ± 5.7	42.6 ± 5.3	0.240

Notes: Group I: isolated MPFL reconstruction; Group II: MPFL reconstruction combined with LPR release.

Abbreviations: MPFL, medial patellofemoral ligament; LPR, lateral patellar retinaculum; IKDC, International Knee Documentation Committee; TT-TG, tibial tuberosity-trochlear groove.

Table 3 Comparison of Postoperative 12th-Month Patella Associated Measurements and Knee Function Between Two Groups

Variables	Group I (n=45)	Group II (n=42)	P value
Congruence angle	15.6 ± 4.2	15.9 ± 5.8	0.782
Patellar tilt angle	7.21 ± 1.45	7.38 ± 1.57	0.601
Lateral patellofemoral angle	8.6 ± 3.1	7.8 ± 3.9	0.291
Postoperative PTQR	22.4 ± 6.2	21.7 ± 6.8	0.617
Postoperative PTQC	27.8 ± 7.4	25.6 ± 8.1	0.189
Lysholm score	84.5 ± 7.1	89.7 ± 8.7	0.003
IKDC score	87.9 ± 7.2	93.1 ± 7.7	0.002

Notes: Group I: isolated MPFL reconstruction; Group II: MPFL reconstruction combined with LPR release.

Abbreviations: MPFL, medial patellofemoral ligament; LPR, lateral patellar retinaculum; IKDC, International Knee Documentation Committee; PTQR, patellar tilt with the quadriceps relaxed; PTQC, patellar tilt with the quadriceps contracted.