Patellar dislocation: cylinder cast, splint or brace? An evidence-based review of the literature
© van Gemert et al.; licensee Springer. 2012
Received: 10 May 2012
Accepted: 20 November 2012
Published: 31 December 2012
Patellar dislocations are a common injury in the emergency department. The conservative management consists of immobilisation with a cylinder cast, posterior splint or removable knee brace. No consensus seems to exist on the most appropriate means of conservative treatment or the duration of immobilisation. Therefore the aims of this review were first to examine whether immobilisation with a cylinder cast causes less redislocation and joint movement restriction than a knee brace or posterior splint and second to compare the redislocation rates after conservative treatment with surgical treatment. A systematic search of Pubmed, Embase and the Cochrane Library was performed. We identified 470 articles. After applying the exclusion and inclusion criteria, only one relevant study comparing conservative treatment with a cylinder cast, brace and posterior splint remained (Mäenpää et al.). In this study, the redislocation frequency per follow-up year was significant higher in the brace group (0.29; p < 0.05) than in the cylinder cast group (0.12) and the posterior splint group (0.08). The proportion of loss of flexion and extension was the highest in the cylinder cast group and the lowest in the posterior splint group (not significant). The evidence level remained low because of the small study population, difference in duration of immobilisation between groups and use of old braces. Also, 12 studies comparing surgical with conservative treatment were assessed. Only one study reported significantly different redislocation rates after surgical treatment. In conclusion, a posterior splint might be the best therapeutic option because of the low redislocation rates and knee joint restrictions. However, this recommendation is based on only one study with significant limitations. Further investigation with modern braces and standardisation of immobilisation time is needed to find the most appropriate conservative treatment for patellar luxation. Furthermore, there is insufficient evidence to confirm the added value of surgical management.
The most important complications of primary acute patellar dislocations are recurrence and continued disability . Consequently, it is important to determine the best treatment providing patellar stability and knee function. However, no consensus seems to exist on the most appropriate means of conservative treatment. Also, the immobilisation time has not been standardised. We, as emergency physicians, are seeking the best possible way to treat patients with acute primary patellar dislocation in the emergency department (ED). Therefore the primary aim of this review is to answer the following clinical query: Does immobilisation with a cylinder cast provide less redislocation and joint movement restriction than a knee brace or posterior splint in patients with primary acute patellar dislocation? Secondly we assessed the redislocation rates in surgical versus conservative treatment.
Search query as used in pubmed, embase and the cochrane library August 17th, 2012
patel* OR kneecap
luxat* OR subluxat* OR dislocat* OR displace* OR disarticulat* OR floating
cylinder cast OR gypsum OR plaster OR splint OR immobilisation OR immobilization OR “conservative treatment” OR brace OR sleeve OR support OR bandage OR orthosis OR nonoperative
Results of the search
Not specified (23)
Not specified (35)
Not specified (20)
Hing # , 2012
Not specified (157)
Cylinder cast (60)
Splint (17) Brace (23)
8 (53) 13 (48)
Brace restricted ROM (13)
Brace free ROM (13)
Reported redislocation rates ranged between 0-38% in patients treated with cylinder casts, between 4-53% in patients treated with splints and 6-54% in patients treated with braces (Table 2). However, the aforementioned single-arm studies did not provide an answer to our clinical question.
Study results: Mäenpää et al. 1997
Treatment arm (n)
Loss of extension
Loss of flexion
RR (CI 95%)
RR (CI 95%)
RR (CI 95%)
Cylinder cast (60)
Posterior splint (17)
Twelve studies reported redislocation rates after surgery compared to conservative treatment [3–11, 13, 15, 16]. Only one study showed a significantly lower redislocation rate in the surgical group . The other studies did not report a significant difference between surgical and non-surgical management.
The query in the Medline, Embase and Cochrane databases resulted in only one relevant article (Mäenpää et al.). Mäenpää et al. recommend using a posterior splint for acute primary patella dislocation because of the low knee joint restriction and low redislocation rates per follow-up year. They did not find a significant difference in the redislocation frequency among the cylinder cast, splint and brace groups. In contrast, they showed that patients treated with a brace exhibited a significantly higher redislocation frequency per follow-up year. This effect might be due to the shorter immobilisation time in the brace group compared to the other groups. Another explanation might be found in the type of brace used: simple straps and knee sleeves. These days knee braces that maintain better patellar alignment are available.
Mäenpää et al. showed the highest frequency of knee joint restriction in patients treated with cylinder casts. However, the difference to the other groups was not significant. This might be the result of the limitation of joint movement caused by the cylinder cast, which might protect against redislocation but may cause degenerative changes in the bone, cartilage and knee ligaments. Moreover, this movement limitation might also be caused by the longer immobilisation time in the cylinder cast group compared to the splint and brace groups. The lack of standardisation of the immobilisation time between groups in the Mäenpää et al. study makes the results unconvincing. Therefore, to find the most appropriate treatment for patellar dislocation, special attention should be given to the immobilisation time.
Although the above-mentioned study represents the best available evidence, the evidence level remains low because of the small study population, difference in immobilisation duration between groups, use of old braces and limitations in the study design.
Furthermore, 11 out of 12 studies comparing surgical and conservative treatment did not report significantly different redislocation rates [3–11, 13, 15, 16]. In conformation with these results, a recently published Cochrane review based on five studies involving 339 participants did not find evidence of lower redislocation rates in patients who were managed with surgical repair compared with those who were managed with conservative treatment .
Based on the best available evidence, the treatment for primary acute patellar dislocation remains controversial. A posterior splint might be the best therapeutic option because of the low redislocation rates and knee joint restrictions. However, this recommendation is based on only one small study with significant limitations. Further investigation with modern braces and standardisation of immobilisation time is needed to find the most appropriate conservative treatment for patellar dislocation.
Furthermore, there is insufficient evidence to confirm the added value of surgical management.
We thank Mendel van Griethuysen and Frank van Kemenade (plaster room, University Medical Center Utrecht) for making cylinder cast models for the images in this review. We thank Mr. Timmers (Medical Photographer, University Medical Center Utrecht) for producing accurate and objective images.
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