Arch Orthop Trauma Surg (2013) 133:209–213 DOI 10.1007/s00402-012-1639-8

ARTHROSCOPY AND SPORTS MEDICINE

Operative vs conservative treatment of traumatic patellar dislocation: results of a prospective randomized controlled clinical trial M. Petri • E. Liodakis • M. Hofmeister • F. J. Despang • M. Maier • P. Balcarek • C. Voigt • C. Haasper • J. Zeichen • D. Stengel • C. Krettek K. H. Frosch • H. Lill • M. Jagodzinski

•

Received: 19 January 2012 / Published online: 9 November 2012 Ó Springer-Verlag Berlin Heidelberg 2012

Abstract Introduction Patellar dislocation is a common knee injury with mainly lateral dislocations, leading to ruptures of the medial patellofemoral ligament in most of the cases. Even though several prognostic factors for patellofemoral instability have been identified so far, the appropriate therapy for patients with patellar dislocation remains a controversial issue. The purpose of this study was to compare the outcome after conservative or operative treatment in patients after first-time patellar dislocation. Patients and methods This randomized controlled clinical trial was designed multicentric including patients from six

This is a multicentric study of the Committee TRAUMA of the AGASociety for Arthroscopy and Joint Surgery and the Committee Arthroscopy of the German Society for Trauma Surgery (DGU). M. Petri (&)  E. Liodakis  C. Haasper  C. Krettek  M. Jagodzinski Trauma Department, Hannover Medical School (MHH), Carl-Neuberg-Straße 1, 30625 Hannover, Germany e-mail: [email protected] M. Hofmeister Trauma Department, Traumacenter Murnau, Prof. Ku¨ntscher-Str. 8, 82418 Murnau, Germany F. J. Despang Trauma Department, DRK Hospital, Alte Frankfurter Str. 12, 57627 Hachenburg, Germany M. Maier Orthopaedic Surgery Department, University Hospital Friedrichsheim, Marienburg Str. 2, 60528 Frankfurt, Germany

German orthopaedic and trauma departments. Twenty patients with a mean age of 24.6 years with first-time traumatic patella dislocation were included and randomized into either a conservative arm or an operative arm. Plain X-ray images of the knee joint (a.p. and lateral view and tangential view of both patellae) were performed in all cases prior to therapy to exclude osteochondral fragments requiring refixation. An MRI was recommended, but not compulsory. Patients were consulted after 6, 12, and 24 months with a questionnaire including the criteria of the Kujala score, recurrent dislocation, and satisfaction. Results The mean Kujala score of the conservative vs operative treatment group was 78.6 vs 80.3 after 6 months (p = 0.842), 79.9 vs 88.9 after 12 months (p = 0.165), and 81.3 vs 87.5 after 24 months (p = 0.339). Redislocation rate after 24 months was 37.5 % in the conservative group C. Voigt  H. Lill Department of Trauma and Reconstructive Surgery, Friederikenstift Hospital Hannover, Humboldt Str 5, 30169 Hannover, Germany J. Zeichen Trauma Department, Johannes-Wesling-Hospital, Hans-Nolte-Str. 1, 32429 Minden, Germany D. Stengel Centre for Clinical Research, Unfallkrankenhaus Berlin, Warener Str. 7, 12683 Berlin, Germany K. H. Frosch Trauma Department, Asklepios Hospital St. Georg, Lohmu¨hlen Str. 5, 20099 Hamburg, Germany

P. Balcarek Trauma Department, University Hospital Go¨ttingen, Robert-Koch-Str. 40, 37075 Go¨ttingen, Germany

123

210

and 16.7 % in the operative group (p = 0.347). Due to the small number of patients that could be included, no significant difference between the groups could be detected. We see a tendency towards better results after operative treatment. Conclusion Our multicentric prospective randomized controlled trial revealed no significant difference between conservative and operative treatment for patients after firsttime traumatic patellar dislocation. However, a tendency towards a better Kujala score and lower redislocation rates for patients with operative treatment was observed. The small number of patients is a limiting factor of the study, leading to results without statistical significance. A meta-analysis including other study0 s level I data is desirable for the future. Keywords Knee  Injury  Patellar instability  Patellar dislocation

Introduction Patellar dislocation accounts for 2–3 % of all knee injuries [1, 2] and commonly occurs to the lateral side, leading to ruptures of the medial patellofemoral ligament (MPFL) in about 90 % of all cases [1, 3]. Treatment can be conservative if there are no other injuries like osteochondral fractures [4]. In case of accompanying injuries, operative treatment is usually required [4]. The current opinion of treating first-time patellar dislocation conservatively and operate in case of recurrent dislocation is empirical and not evidence-based [5]. A systematic review of 70 articles concluded that nonoperative treatment after the first dislocation should be conservative, but with several exceptions [5]. Until today, there have only been five prospective randomized trials comparing conservative and operative treatment after first-time patellar dislocation with inconsistent results [6–11]. An actual meta-analysis of studies comparing conservative and operative treatment indicated lower redislocation rates, but higher rates of patellofemoral osteoarthritis after operative treatement, concluding that these findings should be interpreted very cautiously [12]. Even though several prognostic factors for patellofemoral instability such as trochlear dysplasia, valgus deformity, distal femur internal rotation, occurence in youth, family history, and bilateral symptoms have been identified so far, the appropriate therapy for patients with patellar dislocation remains a controversial issue. The purpose of this study was to compare the outcome after conservative or operative treatment in patients after first-time patellar dislocation.

Arch Orthop Trauma Surg (2013) 133:209–213

orthopaedic and trauma centers. The institutional review board approved the study. Inclusion criteria were isolated, unilateral first-time traumatic patella dislocations in male and female patients between 15 and 40 years of age. Patients with open epiphyses could also be included. Informed consent by the patient or the legal guardian for minors was required. Exclusion criteria were recurrent dislocation, significant anatomical deformities, open injury, patients during pregnancy or lactation, and osteochondral fragments requiring refixation. Plain X-ray images of the knee joint (a.p. and lateral view and tangential view of both patellae) were performed in all cases prior to therapy to exclude osteochondral fragments requiring refixation. An MRI was recommended, but not compulsory. The study was performed with an adaptive design according to O0 Brien-Fleming [13]. Eighty-eight patients were scanned for the study and asked to participate. Sixtyfour patients declined to participate, mostly for mistrust of not receiving the best treatment. Twenty-four patients were included, among which four had to be excluded later as a loss-to-follow-up. Finally 20 patients (7 female (35 %) and 13 male (65 %)) with a mean age of 24.6 years (range 16–40) randomized into either a conservative arm (8 patients) or an operative arm (12 patients) remained for a complete follow-up of 24 months (Fig. 1). With use of a sealed envelope method utilizing a software generated block randomization patients were randomized in the individual centers. Surgery was limited to diagnostic arthroscopy followed by open soft tissue repairs including mainly suture and optional tightening of the ruptured medial structures in a manner of ‘‘repair the tear’’. MPFL-plastics were not performed in this study. A lateral release was optional. Bony corrections like osteotomies of the tibial tuberosity were excluded. Patients of both the conservative and the operative arm were treated with a DonJoyTM ROM-brace with 0-0-60° extension/flexion for the first 3 weeks and 0-0-90° extension/flexion for the following 3 weeks. Partial weightbearing of 15 kg on crutches was applied for the first 3 weeks, followed by progression to pain-adapted full weigthbearing. Patients were consulted with a questionnaire including the criteria of the Kujala score [14], about recurrent dislocation, and satisfaction after 6, 12, and 24 months.

Statistical analysis Patients and Methods This prospective randomized controlled trial was designed multicentric including patients from six major German

123

Statistical analysis was evaluated between the different groups using Mann–Whitney-U test and student0 s two tailed t test for continuous data. For categorial values the

Arch Orthop Trauma Surg (2013) 133:209–213

211

Fig. 1 ConsortTM flowchart of the randomization process

Assessed for eligibility (n=88)

Excluded (n=64) ♦ Not meeting inclusion criteria (n=0) ♦ Declined to participate (n=64) ♦ Other reasons (n=0)

Randomized (n=24)

Allocated to conservative therapy (n=10) ♦ Received allocated intervention (n=10)

Allocated operative therapy (n=14) ♦ Received allocated intervention (n=14)

♦

♦

Did not receive allocated intervention (n=0)

Did not receive allocated intervention (n=0)

Lost to follow-up (1 patient moved out of the area, contact data of 1 patient was incomplete) (n=2)

Lost to follow-up (2 patients moved out of the area) (n=2)

Discontinued intervention (n=0)

Discontinued intervention (n=0)

Analysed (n=8) ♦ Excluded from analysis (n=0)

Fischer0 s exact test and the Pearson-Chi-square test were used. The SPSS (SPSS 15.0, SPSS Inc., Chicago, IL, USA) software package was used. A p value \0.05 was considered to be statistically significant.

Results There was no relevant difference between the sex distribution of the conservative (62.5 % male and 37.5 % female) and the operative group (66.7 % male and 33.3 % female, p = 1.0). Mean age in the conservative group was 21.6 ± 5.6 and 27.2 ± 9.0 years in the operative group (p = 0.14). 47.4 % had right side dislocation, 52.6 % had a left side dislocation. 37 % of the patients were smokers, none of the patients suffered from diabetes mellitus. 26.3 % never practiced sports, 36.8 % seldom, 31.6 % often, and 5.3 % were sports professionals. Concerning sports activities, there was no significant difference between the patients of both groups (p = 0.469). For both groups together, the mean Kujala score was 79.6 ± 17.0 after 6 months, 85.3 ± 14.1 after 12 months, and 85.0 ± 15.8 after 24 months. The mean Kujala score of the conservative vs operative treatment group was 78.6 vs 80.3 after 6 months (p = 0.842), 79.9 vs 88.9 after 12 months (p = 0.165), and 81.3 vs 87.5 after 24 months (p = 0.339, Table 1).

Analysed (n=12) ♦ Excluded from analysis (n=0)

Table 1 Kujala score and redislocations rates Conservative

Operative

p value

6 months

78.6 ± 14.7

80.3 ± 19.2

0.842

12 months

79.9 ± 18.5

88.9 ± 9.4

0.165

24 months

81.3 ± 19.2

87.5 ± 13.3

0.339

Redislocation 24 months

37.5 %

16.7 %

0.347

Table 2 Episodes of instability (p = 0.079) Conservative

Operative

None

3/8 (37.5 %)

5/11 (45.5 %)

Once per month

0/8 (0 %)

3/11 (27.3 %)

Several times per month

2/8 (25.0 %)

0/11 (0 %)

Once per week

2/8 (25.0 %)

0/11 (0 %)

Several times per week

0/8 (0 %)

2/11 (18.2 %)

Once per day

0/8 (0 %)

1/11 (9.1 %)

Several times per day

1/8 (12.5 %)

0/11 (0 %)

The results concerning episodes of instability are summarized in Table 2. Taken both groups together, 25 % of the patients (5/20) sustained a redislocation, 75 % (15/20) remained stable after 24 months. In the conservative group, 37.5 % (3/8) sustained a redislocation, 62.5 % (5/8) remained stable. In the operative group, 16.7 % (2/12) sustained a

123

212

Arch Orthop Trauma Surg (2013) 133:209–213

Table 3 Consideration of results (p = 0.220) Conservative

Operative

Excellent

0/8 (0 %)

3/11 (27.3 %)

Good

4/8 (50 %)

5/11 (45.5 %)

Fair

4/8 (50 %)

2/11 (18.2 %)

Poor

0/8 (0 %)

1/11 (9.1 %)

redislocation with 83.3 % (10/12) remaining stable after 24 months (p = 0.347, Table 1). The patients subjective consideration of results is shown in Table 3. The power of this study is 25 % with Beta of 0.75. Power analysis revealed that at least 65 patients would be needed to reach a power of 80 % or more. The study design which was approved by the ethical committee scheduled a preterm termination of the study if less than 60 patients could be included within one year.

Discussion The most important finding of our study was that patients after operative treatment after first-time patellar dislocation by trend reach a higher Kujala score and lower rates of redislocation compared to conservative treatment. For many years, mainly overweight adolescent girls were considered to be at risk for patellofemoral instability [15, 16]. Recent studies however show that patellar dislocation is common in athletically active adolescents and young adults with an almost identical distribution between the sexes and a peak between 10 and 20 years of age [2, 4, 5, 15, 17]. Most of the first-time patellar dislocations occur during sporting activities, with incidences spreading from 55 % [18] over 61 % [17] and 65 % [2] up to 72 % [15]. The gender ratio of our population was 35 % female and 65 % male, which shows an overweight of males compared to the findings in literature, where usually an almost identical distribution between the sexes is described [2, 4, 5, 9, 15, 17, 19]. More detailed epidemiological studies revealed a male-to-female ratio of 46 % men and 54 % women among 1,765 patients with first-time patellar dislocations [5]. The studies of Sillanpa¨a¨ et al. [8, 20] which were conducted in a military hospital are of particular interest and may be most comparable to our study as they contained 94.7 % [20] respectively 92.5 % [8] male patients. Sillanpa¨a¨s results were heterogeneous, revealing lower rates of redislocation after surgical treatment in young male patients with traumatic patellar dislocation in one study [8], and equal redislocation rates but better regain of preinjury activity after surgery in the other study [20]. In both studies, they could not show clear subjective benefits in the long-term follow-up compared to conservative treatment.

123

The mean age of 24.6 years and the range of 16–40 of our study group is slightly older than the study population in most other studies, usually describing a peak between 10 and 20 years of age [2, 4, 5, 15, 17]. Until today, there have only been five prospective randomized trials comparing conservative and operative treatment after first-time patellar dislocation [6–11]. In 2005, Nikku et al. [7] reported the 7-year follow-up results of 127 patients after first-time patellar dislocation who had been randomized into 57 conservatively treated and 70 operatively treated. In the conservative group, 30 % of the patients retained a stable patella, redislocations occurred in 39 %. In the operative group, 36 % remained stable and 31 % suffered a redislocation. In the conservative group, 81 % of the patients were satisfied with their result, mean Kujala score was 90–94. In the operative group, only 67 % of the patients considered their result satisfying with a mean Kujala score of 88–89 [7]. The same author had previously reported the 2-year-results of the trial [6], showing no benefit from surgery compared to conservative treatment. As a conclusion, they at this time could not recommend routine surgery after first-time patellar dislocation. Their data differs remarkably from our study as their randomization was conducted using the date of birth, 50 % of their patients were below 16 years of age, and 54 of their 70 patients had a lateral release [6]. In 2008, Christiansen et al. [10] randomized 80 patients with primary patellar dislocation during delayed arthroscopy (mean 50 days after trauma) into either conservative treatment with a ROM-brace or operative treatment by reinsertion of the MPFL to the adductor tubercle. They performed a follow-up of 2 years, finding a mean Kujala score of 78 and redislocation rate of 20 % in the conservative group and a mean Kujala score of 85 and redislocation rate of 17 % in the operative group [10]. Palmu et al. [9] randomized a cohort of 74 patellar dislocations in children and adolescents younger than 16 years into either a conservative arm or an operative arm with immediate repair of the damaged medial structures and an optional lateral release. They performed a clinical follow-up after 2 years and phone-call questionnaires after a mean of 6 and 14 years, which is the longest follow-up so far in literature. 75 % of the conservative group considered their result good or excellent, so did 66 % of the operative group. Redislocation rates were at 71 % in the conservative group and 67 % in the operative group. They found a positive family history of patellar instability to be the only significant predictor for the longterm outcome. Therefore, they recommended to not routinely repair the medial structures acutely after patellar dislocation. This study used a lateral release in 88 % of the operatively treated cases, which may have contributed to residual instability [9].

Arch Orthop Trauma Surg (2013) 133:209–213

A prospective trial from Brazil 2008 dividing 33 patients into a conservative treatment and an operative treatment group revealed a significantly better Kujala score (92/100) and no recurrence in the operative group, compared to a Kujala score of 69/100 and eight relapses in the conservative group [11]. In 2009, Sillanpa¨a¨ et al. [8] compared 40 patients with first-time patellar dislocation in a follow-up of 7 years. Redislocations occurred in 29 % of conservatively treated patients and 0 % of operatively treated patients. This rate of redislocation is the lowest in the literature and could be caused by the fact that operative treatment was not limited. There were more than 90 % males within the study. Instability remained in 48 % of the conservative group and 12 % of the operative group. The mean Kujala score was 90 in the conservative group and 91 in the operative group [8]. Due to the small number of patients that could be included, no difference between the groups could be detected. We see a tendency towards better results after operative treatment.

Conclusions Our multicentric prospective randomized controlled trial revealed no significant difference between conservative and operative treatment for patients after first-time traumatic patellar dislocation. However, a tendency towards a better Kujala score and lower redislocation rates for patients with operative treatment was observed. The small number of patients is a limiting factor of the study, leading to results without statistical significance. Future prospective studies including a higher number of patients and a meta-analysis including other study0 s data is desirable for the future. Acknowledgments We greatly acknowledge funding of OrmedDJOTM for this study. Conflict of interest of interest.

The authors declare that they have no conflict

References 1. Arendt EA, Fithian DC, Cohen E (2002) Current concepts of lateral patella dislocation. Clin Sports Med 21(3):499–519 2. Balcarek P, Jung K, Ammon J, Walde TA, Frosch S, Schuttrumpf JP, Sturmer KM, Frosch KH (2010) Anatomy of lateral patellar instability: trochlear dysplasia and tibial tubercle-trochlear groove distance is more pronounced in women who dislocate the patella. Am J Sports Med 38(11):2320–2327. doi:10.1177/0363546510373887 3. Burks RT, Desio SM, Bachus KN, Tyson L, Springer K (1998) Biomechanical evaluation of lateral patellar dislocations. Am J Knee Surg 11(1):24–31

213 4. Oestern S, Varoga D, Lippross S, Kaschwich M, Finn J, Buddrus B, Seekamp A (2011) Patella dislocation. Unfallchirurg 114(4):345–359. doi:10.1007/s00113-011-2012-z 5. Stefancin JJ, Parker RD (2007) First-time traumatic patellar dislocation: a systematic review. Clin Orthop Relat Res 455:93–101. doi: 10.1097/BLO.0b013e31802eb40a 6. Nikku R, Nietosvaara Y, Kallio PE, Aalto K, Michelsson JE (1997) Operative versus closed treatment of primary dislocation of the patella. Similar 2-year results in 125 randomized patients. Acta Orthop Scand 68(5):419–423 7. Nikku R, Nietosvaara Y, Aalto K, Kallio PE (2005) Operative treatment of primary patellar dislocation does not improve medium-term outcome: a 7-year follow-up report and risk analysis of 127 randomized patients. Acta Orthop 76(5):699–704. doi: 10.1080/17453670510041790 8. Sillanpaa PJ, Mattila VM, Maenpaa H, Kiuru M, Visuri T, Pihlajamaki H (2009) Treatment with and without initial stabilizing surgery for primary traumatic patellar dislocation. A prospective randomized study. J Bone Joint Surg Am 91(2):263–273. doi: 10.2106/JBJS.G.01449 9. Palmu S, Kallio PE, Donell ST, Helenius I, Nietosvaara Y (2008) Acute patellar dislocation in children and adolescents: a randomized clinical trial. J Bone Joint Surg Am 90(3):463–470. doi: 10.2106/JBJS.G.00072 10. Christiansen SE, Jakobsen BW, Lund B, Lind M (2008) Isolated repair of the medial patellofemoral ligament in primary dislocation of the patella: a prospective randomized study. Arthroscopy 24(8):881–887. doi:10.1016/j.arthro.2008.03.012 11. Camanho GL, Viegas Ade C, Bitar AC, Demange MK, Hernandez AJ (2009) Conservative versus surgical treatment for repair of the medial patellofemoral ligament in acute dislocations of the patella. Arthroscopy 25(6):620–625. doi:10.1016/j.arthro. 2008.12.005 12. Smith TO, Song F, Donell ST, Hing CB (2011) Operative versus non-operative management of patellar dislocation. A meta-analysis. Knee Surg Sports Traumatol Arthrosc 19(6):988–998. doi: 10.1007/s00167-010-1355-2 13. Hartung J (2006) Flexible designs by adaptive plans of generalized Pocock- and O’Brien-Fleming-type and by self-designing clinical trials. Biom J 48(4):521–536 14. Kujala UM, Jaakkola LH, Koskinen SK, Taimela S, Hurme M, Nelimarkka O (1993) Scoring of patellofemoral disorders. Arthroscopy 9(2):159–163 15. Atkin DM, Fithian DC, Marangi KS, Stone ML, Dobson BE, Mendelsohn C (2000) Characteristics of patients with primary acute lateral patellar dislocation and their recovery within the first 6 months of injury. Am J Sports Med 28(4):472–479 16. Cash JD, Hughston JC (1988) Treatment of acute patellar dislocation. Am J Sports Med 16(3):244–249 17. Fithian DC, Paxton EW, Stone ML, Silva P, Davis DK, Elias DA, White LM (2004) Epidemiology and natural history of acute patellar dislocation. Am J Sports Med 32(5):1114–1121. doi: 10.1177/0363546503260788 18. Nietosvaara Y, Aalto K, Kallio PE (1994) Acute patellar dislocation in children: incidence and associated osteochondral fractures. J Pediatr Orthop 14(4):513–515 19. Weber-Spickschen TS, Spang J, Kohn L, Imhoff AB, Schottle PB (2010) The relationship between trochlear dysplasia and medial patellofemoral ligament rupture location after patellar dislocation: an MRI evaluation. Knee. doi:10.1016/j.knee.2010.04.002 20. Sillanpaa PJ, Maenpaa HM, Mattila VM, Visuri T, Pihlajamaki H (2008) Arthroscopic surgery for primary traumatic patellar dislocation: a prospective, nonrandomized study comparing patients treated with and without acute arthroscopic stabilization with a median 7-year follow-up. Am J Sports Med 36(12):2301–2309. doi:10.1177/0363546508322894

123