Long-Term Follow-Up of Nonoperatively and Operatively Treated Acute Primary Patellar Dislocation in Skeletally Immature Patients
Table 1
Descriptive data and outcomes of 51 patients.
Patellar dislocation
Group A Nonoperatively treated patients
Group B Patients treated operatively during acute phase
Group C Patients treated operatively due to recurrence
Girls : boys
16 : 17
4 : 3
9 : 2
Age at injury (years)a
13.5 ± 1.3
12.6 ± 2.3
13.3 ± 1.5
Follow-up time (years)a
7.7 ± 1.5
7.0 ± 1.4
7.3 ± 1.5
Trochlear dysplasia
67% (22 of 33)
83% (5 of 6)
64% (7 of 11)
Patella alta
33% (11 of 33)
33% (2 of 6)
38% (3 of 8)
Subjective knee functiona
KOOS subscales at follow-upb
(i) Pain (M = 92, F = 92)
90 ± 14
92 ± 8
86 ± 9
(ii) Symptoms (M = 87, F = 89)
82 ± 14
82 ± 11
78 ± 12
(iii) Function in daily living (M = 94, F = 95)
94 ± 12
97 ± 4
93 ± 6
(iv) Sports and recreation (M = 85, F = 86)
77 ± 24
79 ± 15
66 ± 17
(v) Quality of life (M = 85, F = 84)
69 ± 20
76 ± 19
60 ± 14
Kujala score at follow-upc
84 ± 10
84 ± 7
75 ± 15
Objective knee functiona
Peak torque/body weight
(i) Extension (90 degr/s)
187.2 ± 59.5
195.6 ± 57.4
157.9 ± 63.2
M: 220 ± 43
M: 242 ± 50
M: 231 ± 30
F: 152 ± 56
F: 161 ± 34
F: 142 ± 57
(ii) Flexion (90 degr/s)
106.3 ± 34.4
103.6 ± 31.7
113.8 ± 57.6
M: 128 ± 26
M: 124 ± 36
M: 208 ± 77
F: 83 ± 27
F: 88 ± 20
F: 93 ± 26
(iii) H/Q ratioe
0.58 ± 0.16
0.54 ± 0.12
1.03 ± 1.30
LSI, peak torque in extensionf
86 ± 17%
89 ± 15%
81 ± 32%
30 s mini squat test injured sideg
35 ± 15
36 ± 18
34 ± 13
LSI, 30 s mini-squat testf
93 ± 21%
97 ± 8%
99 ± 32%
Redislocation after latest treatmenth
67% (22 of 33)
43% (3 of 7)
18% (2 of 11)
The results are presented as the mean ± 1 SD.
bKOOS: knee injury and osteoarthritis outcome score, range 0–100; higher scores indicate a better outcome. Values in parentheses are the reference mean values reported for males, M, and females, F, 18–34 years of age in a population-based study by Paradowski et al. [27].
cKujala anterior knee pain score, range 0–100; higher scores indicate a better outcome, and healthy individuals score 99.9 [25].
dMean values of 42 knees.
eH/Q ratio: hamstrings to quadriceps ratio, normal value <0.6 [30].
fLSI: leg symmetry index, <85% of the unaffected side is considered pathological [34, 35].
gHealthy adults perform 30 times of knee bending/30 s [31].
h≥1 redislocation.
