Treatment for first-time patellar dislocations in the Netherlands; a wide variety of strategies

M.R. van der Valk D. Vermeulen L. Kaas Department of Orthopaedic Surgery St. Antonius Hospital, Utrecht, the Netherlands

Abstract Introduction Patellar dislocations are a common problem in the casualty department (5.8 to 42 persons per 100.000 per year). In the Netherlands, a conservative treatment is usually chosen after a first-time patellar dislocation, although there is no consensus of what this conservative treatment should entail. The aim of this study was to assess the different treatment strategies used for first-time patellar dislocations in the Netherlands. Material and methods An online questionnaire was sent to physicians of the emergency, surgical and orthopaedic departments of 71 general and academic hospitals in the Netherlands. The questionnaire assessed the preferred treatment strategy used in primary patellar dislocations, duration of treatment and clinical evaluation of patients. Results A total of 147 responses were acquired (response rate 49%), of which 98% agreed on an initial conservative treatment in a first-time patellar dislocation. A posterior splint was used by 53 physicians (36%), a brace by 50 (34%) and a cast by 28 of the respondents (19%). Half of the respondents (n=73, 50%) treated patients for a duration of 6 weeks, 18 (12%) of the respondents for 4 weeks and 24 (16%) for 2 weeks. Conclusion In the Netherlands, treatment of a first patellar dislocation differs greatly between hospitals and physicians. Most physicians agree on a conservative treatment, although the treatment strategy and duration of treatment differs strongly. Further research is required to gain more evidence and to uniformise protocols in treatment after a first-time patellar dislocation.

Introduction Patellar dislocation is a serious problem with approximately 5.8 to 42 persons per 100.000 per year suffering from a patellar dislocation.1-4 Therefore, patellar dislocations are a common problem in the casualty department.2 It mainly affects young and active adolescents.2,4 Common trauma mechanisms include flexion of the knee in the valgus position or a direct trauma on the patella.5 Known risk factors for a patellar dislocation are: female gender, patella alta, trochlear dysplasia and an excessive tibial tuberosity-trochlear groove (TT-TG) distance.2,6 In the majority of patellar dislocations, the medial patellofemoral ligament (MPFL) is torn7 and the cartilage in the knee is damaged (95%).8 The first step of treatment after dislocation is reduction of the patella to its normal position. After reduction, X-rays, including a skyline view of the injured knee, are usually obtained to assess if there are any loose bony fragments or other associated injuries to the joint.7,9 There is a broad choice of treatment strategies following reduction, which can be divided into direct surgical intervention or a non-surgical treatment. Surgical intervention consists of MPFL reconstruction or patellar realignment procedures.10 Non-surgical intervention consists of (partial) immobilisation of the knee by restriction of flexion in the knee or functional mobilisation. Restricted flexion gives the MPFL the opportunity to heal. This can be achieved using either a posterior splint, a cast or a flexion-limiting brace.11-13 If functional mobilization is selected, the knee is often supported using elastic bandages,14 a brace with full range of motion or taping of the knee.10,12 After conservative treatment the redislocation rate, of first-time patellar dislocations is high at 17-44%2,13,15 and patients frequently experience persistent pain and instability in the knee (63%).14 Aside of the high redislocation risk, a period of immobilisation can induce atrophy and restriction in the range of motion.14 In the currently available literature, a wide variety of treatment strategies for first-time patellar dislocations are described. However, there is no consensus on the optimal treatment of first-time patellar dislocations and literature lacks studies of sufficient quality.14,16,17 The aim of this study was to assess the different treatment strategies for first-time patellar dislocations used in the Netherlands. In Dutch guidelines, the first choice of treatment fora first-time patellar dislocation is conservative if no concomitant osteochondral fractures are present.18 Therefore, this study will focus on conservative treatment options.

Methods An online questionnaire was developed in Google Forms®. The questionnaire is shown in appendix A. The invitation to complete this questionnaire was sent to 71 general and academic hospitals in the Netherlands with an emergency department. All physicians involved in the treatment of first-time patellar dislocations; including trauma surgeons, orthopaedic surgeons and casualty physicians; were invited. Attending physicians, residents in training, residents not in training and physician assistants were asked to fill in the questionnaire. The main purpose of the questionnaire was to assess the preferred treatment strategy used by their department in primary patellar dislocations; surgical or conservative; and if conservative, if either immobilisation by cast or a splint, functional mobilisation using a brace, tape or bandages or a combination of these techniques was used. Other questions concerned whether there is a standard treatment protocol in the hospital, the type of imaging routinely performed and which physical examination is performed. Data was collected in Google Forms® and further analysed using Excel (Microsoft Office Standard 2010).

Results The online questionnaire was open for response from April to September 2017. A total of 147 responses were received . A response was obtained from 35 of the 71 approached hospitals (49.3%) (fig 1). Of the respondents, 71% worked as an attending physician, 16% as a resident in training, 12% as a resident not in training and 2% as a physician assistant. Treatment strategies Of the respondents, 98% agreed on initial conservative treatment in a first-time patellar dislocation case. The remaining 2% also favoured conservative treatment, although they let the choice of treatment depend on concomitant injuries such as avulsion fractures. A posterior splint was the treatment of choice for 53 physicians (36%). A brace was the preferred treatment method for 50 (34%) and a cast for 28 of the respondents (19%). 7 respondents treated patients by a short (1 to 2 weeks) immobilisation using a splint or cast first followed by controlled mobilisation using a brace or tape. 2 respondents prescribed physiotherapy as the primary choice of treatment. 1 respondent only used mobilisation with tape as primary treatment. 7 respondents indicated that they used multiple treatments in patellar dislocation (fig 2). In 76% of the hospitals a standard treatment protocol was present; although only in 1 of the 35 hospitals all responding physicians did follow the treatment as proposed in the protocol.


Figure 1. Distribution of the departments of the respondents


Figure 2. The variation in first-time patellar dislocation treatment across the respondents

Duration of treatment Half of the respondents (n=73, 50%) treated patients for a duration of 6 weeks. 18 (12%) of the respondents continued treatment for 4 weeks, 2 (1%) for 3 weeks, 24 (16%) for 2 weeks and 2 (1%) for 1 week. 2 (1%) had an initial treatment for longer than 6 weeks and 26 (18%) were unfamiliar with the duration of treatment as they merely worked in casualty and did not perform the follow-up of patients at the outpatient clinic (fig 3). Imaging An X-ray of the knee after a patellar dislocation was routinely performed by 123 respondents (84%). The indication for more extensive imaging such as a computed tomography scan (CT-scan) or magnetic resonance imaging (MRI-scan) varied enormously across the respondents. An additional scan was performed by 73 respondents based on the result of the X-ray, by 15 respondents based on physical examination and by 39 respondents based on the mechanism of the trauma. When complaints persisted, 8 respondents ordered an additional scan and 13 when recurrence of patellar dislocation occured. 4 respondents always performed a scan after a first-time patellar dislocation and 18 respondents replied that they never perform further imaging.


Figure 3. Duration of treatment as responded

Discussion There are many treatment strategies described for first-time patellar dislocations ,including a brace, plaster cast, tape or surgical intervention. In the current literature, no consensus is reached on which of these treatments should be chosen to decrease pain and instability after treatment and to reduce the risk of redislocation.14,16,17 Assessments of clinical imaging and different treatment strategies used in the Netherlands can help to develop a more standardised protocol how to assess and treat first-time patellar dislocations. In this study we questioned physicians in the Netherlands how they treat first-time patellar dislocations. Results show that the treatment strategies differ greatly between Dutch hospitals and between treating physicians. If there are no fractures or concomitant injuries, an unanimous preference for conservative treatment exists with a roughly even distribution between immobilisation through a brace or posterior splint. A minority treats patients with a plaster cast. Of the respondents, 76% indicated that the hospital had a protocol which prescribed how to treat first-time patellar dislocations. What was striking, was that, despite the presence of a protocol, different treatments were carried out in 20 out of 23 hospitals who had multiple respondents. This may be caused by the weak availability of evidence in literature, causing ambiguity which treatment is best, which leads to physicians choosing the best treatment based on their own experience. Another cause could be that the physicians are not familiair with the treatment prescribed in the local protocol or the protocol being outdated. Additionally, the variation in the imaging performed after the dislocation is noticeable. Some respondents did not perform a standard X-ray after reduction, whilst other respondents always performed an X-ray and an additional scan in patients with a first-time patellar dislocation. Luhmann et al. described the findings of arthroscopy in all patients being surgically treated after a patellar dislocation. X-ray results showed that 27% of patients had an avulsion fracture of the lateral patella, 2% had a patellar fracture and in 1 patient an osteochondral defect was seen. Arthroscopy showed osteochondral defects in 73%, 15% of patients had a loose body and 10% a meniscal tear.19 To avoid missing these injuries , an X-ray should be performed in every patient and an additional scan should be performed if there is a suspicion of concomitant injuries. Duerr et al. conclude in their review that in every patient an anteroposterior and lateral X-ray should be made. They advise an additional CT-scan to detect abnormalities in the osseous anatomy and a MRI to diagnose tears in soft tissues such as ligaments or osteochondral lesions.9 In the literature, only 1 other study examining the application of the different treatment strategies was found, although concerning physiotherapists. Smith et al describe the treatment by physiotherapists of a first-time patellar dislocation, showing that most of this group treats their patients with exercises (74% quadriceps exercises and 64% vastus medialis oblique (VMO) specific exercises). What was triking was that most of these therapists did not always apply the same treatment to every patient. Casts or posterior splints were never applied and most physiotherapists applied a brace in less than 24% of the patients or never after a first-time patellar dislocation. Different taping techniques were used, although also in the minority of patients.20 A few studies have been published that compare the outcomes of the several conservative treatments. Maenpaa et al. compared 3 groups, one group treated with a plaster cast, the 2nd with a posterior splint, and the 3rd group treated with a patellar bandage or a brace. They found a higher recurrence rate when patellar bandages and braces were used compared to a plaster cast and posterior splint in a total of 100 patients. No other significant differences were found.14 Kaewkongnok et al. compared treatment with a brace for a duration of 2, 4 and 6 weeks and treatment with a brace followed by bandaging in a group of 1366 patients. The duration of the treatment with a brace did not significantly change the redislocation rate.15 Armstrong et al. performed a feasibility study for a randomised controlled trial comparing 5 weeks immobilisation with a cylinder cast with mobilisation after 1 week of immobilisation in 6 patients. They did not find significant differences in pain, the Lysholm Knee score and disability at the follow-up after 3 months.12 Only Maenpaa et al. found a significant difference in outcomes between the conservative treatment strategies; the level of evidence in the best treatment strategy in first-time patella dislocation is very low.14 The main limitation of the current study is the low response rate of 49.3%. A higher response rate would have improved the reliability and generalisability of this study. What may have influenced the results is that 45% of the responding physicians worked in the casualty department. In the Netherlands, these physicians treat most of the patients seen in casualty and consult other specialities if necessary. They only initiate treatment for the first week or weeks, after which follow-up is performed by an orthopaedic surgeon, trauma surgeon or resident. This may have influenced different outcomes;for example, the assessed information about the duration of treatment and indication for further imaging. This study shows a wide variation in the clinical assessment and treatment of first-time patellar dislocations in the Netherlands. A nationwide protocol or guideline could help to improve outcomes and decrease redislocation rates. However, literature does not provide sufficient evidence to develop such a protocol. A retrospective study, comparing the outcomes of different conservative treatment modalities, followed by a prospective study or randomised controlled trial, could provide the evidence required to make a recommendation for clinical practice. To uniformise treatment, sufficient, high quality research is required whether a knee should be immobilised, what theduration of immobilisation should be, or if quick functional mobilisationis indicated after a first-time patellar dislocation. If there is sufficient, high quality evidence on this subject, protocols can be adjusted and physicians can be stimulated to follow their protocols to improve the results of non-operative treatment of first-time patellar dislocation.

Conclusion In the Netherlands, treatment of a first patellar dislocation differs greatly between hospitals and physicians. Most physicians agree on a conservative treatment, however about a third prescribe a cylinder cast for a few weeks, others treat their patients with a brace or posterior splint. Also, duration of treatment varies from 2 to 6 weeks. Further research is required to gain more evidence and to uniformise protocols for treatment after a first-time patellar dislocation. Disclosure Statement The authors do not have any conflicts of interest to declare.

Acknowledgments We want to thank Nienke Wolterbeek for the advises for revision on the manuscript.

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