LIVRE JDG 2012

P. Sillanpää

in three categories based on location: at the

level of the MPFL patellar insertion, at the

midsubstance of the MPFL and medial

retinaculum, and at the femoral origin of the

MPFL (Table 2) [6, 12]. Therefore, MRI is

recommended in cases of primary dislocation

to verify the diagnosis, evaluate additional

injuries, and, importantly, describe the anatomic

factors of the patellofemoral joint [6, 26-30].

Prospective studies report variable results after

surgical treatment for patellar dislocation [3].

Two prospective randomized studies described

better patellar stability after MPFL repair

compared with conservative treatment [5, 31].

However, only one study described clinically

significant improvement in subjective outcome

[31]. The recent study included MPFL

reinsertion with anchors [31], showing more

favorable results with surgical treatment. All of

the prospective randomized studies utilized

different kinds of MPFL repair [5, 21, 23, 31,

33]. To date, no study has compared MPFL

reconstruction to nonoperative treatment in a

prospective and randomized study setting.

MPFL repair by sutures is not better than

nonsurgical treatment, and does not decrease

recurrent instability rate in skeletally immature

children and do not improve subjective results

in adults [5, 21, 23]. Acute arthroscopic MPFL

repair is also not superior to nonsurgical

management [12]. Arthroscopic repair is likely

an insufficient method to approach all the

MPFL injury locations. Delayed repair is

usually not targeted to the previous injury

location and is therefore not useful [32-34].

Table 1: Risk factors for acute traumatic primary patellar dislocations among military conscripts (median

and standard deviation). Reprinted with permission of Wolters Kluwer Health (Sillanpaa P, Mattila VM,

Iivonen T, et al. Incidence and risk factors of acute traumatic primary patellar dislocation. Med Sci Sports

Exerc. 2008;40: 606-611.) [1]

* considered significant with p-value < 0.05

Risk factor

Acute traumatic

primary patellar

dislocation (n=75)

Healthy controls

(n=130,421)

p-value

Sex

- Male

- Female

128,642

1,992

0.283

Age (y)

19.8 (0.8)

20.0 (1.3)

0.287

Height (cm)

180.3 (7.2)

178.5 (6.7)

0.031*

Weight (kg)

77.2 (4.3)

73.2 (12.7)

0.014*

Muscle strength

16.4 (3.5)

16.4 (3.6)

0.960

Run test (m)

2500 (371)

2520 (355)

0.703

Body mass index

23.7 (3.8)

22.9 (3.5)

0.105

Table 2: Classification on medial patellofemoral ligament (MPFL)

injuries based on injury location and reported incidence in the literature [6, 26-30]

MPFL injur

classification

Anatomical description

Proportion in

primary dislocations

Mean reported

incidence

Patellar

MPFL patellar attachment

13-76%

54%

Midsubstance

MPFL midsubstance

(region between patellar and

femoral attachments)

0-30%

12%

Femoral

MPFL femoral attachment

12-66%

34%