16.1.11-2 figure 1.jpg
16.1.11-2 figure 2.jpg
16.1.11-3 figure 3.jpg
Sleeve Fracture of the Patella: A Case Report

Virinderpal Singh Chauhan,1 Michael Maru 2
Rift Valley Provincial General Hospital, Nakuru
PCEA Kikuyu Hospital, Nairobi
Correspondence to: Dr. Virinderpal Chauhan, PO Box 3273–20100 Nakuru, Kenya; Email:dr.chauhansingh@gmail.com

Summary
Sleeve fractures form an integral part of the patellar fractures seen in children, which in their own entity are rare injuries. Diagnosis is usually missed early due to lack of awareness, and X-ray features are tricky if one is not aware of or familiar with the anatomy of an immature patella. This propagates neglect and outcomes are undesirable for the patient. We present a case of a 12-year-old boy who presented to our facility with a sleeve fracture that was initially missed in the outpatient clinic. Open reduction and repair with non-absorbable sutures was done and the construct protected with a back slab. Early diagnosis and surgical management are critical to favorable outcomes in these injuries.
 
Key words: Patella, Sleeve fracture, Pediatrics Ann Afr Surg. 2019; 16(1):43–45
DOI:http://dx.doi.org/10.4314/aas.v16i1.11
Conflicts of Interest: None
Funding: None
© 2019 Author. This work is licensed under the Creative Commons Attribution 4.0 International License.

Introduction

Sleeve fractures are rare in the skeletally immature child and represent chondral or osteochondral injuries that occur between the cartilage sleeve and the main part of the patella and ossific nucleus. Fractures of the patella collectively form 1% of all fractures, with sleeve fractures representing 57% of these (1–3). This is due to the anatomy of the immature patella, which begins to ossify at about 3–6 years of age and is surrounded by a layer of protective cartilage and soft tissue. It is this eggshell-like fragment that is avulsed that consists of cartilage, periosteum and retinaculum (1). The greatest challenge is the early diagnosis of these fractures, which are often missed or delayed because much of the fragment is unossified and can be missed on plain radiographs, these fractures are rare(4), and primary clinicians lack knowledge of them (5). At times the only indication of this fracture is a patella alta that is determined using the Insall-Salvati index. Neglect or delayed diagnosis is common and disastrous to the patient, who may go on to develop extensor lag and developmental disturbances of the patella (6). Our patient presented with a knee swelling after indirect trauma (pain while jumping for the ball in football); an initial diagnosis of patella tendon rupture had been made at a different facility. Misdiagnosis is common for the reasons already stated. Emphasis is on anatomical reduction and stabilization, which can be carried out using various methods. The aim of this paper is to highlight the importance of understanding the anatomy of an immature patella and of employing various teaching aids to make an early and accurate diagnosis. We hope this will aid in reducing the number of neglected cases or those cases that have been misdiagnosed or delayed.

 

Case Report

A 12-year-old boy was seen at the Presbyterian Church of East Africa (PCEA) Kikuyu Hospital Orthopedic and Rehabilitation Center in February 2016 with complaints of pain and inability to extend the right knee. He incurred the injury after a fall while playing football, which he described as his knee ‘giving way’. No previous incident was reported. On examination, swelling of the right knee was noticed with tenderness on palpation greater on the anterior aspect. A palpable gap on the inferior aspect of patella was recorded and a high riding patella noted. Straight leg test was negative. Radiographs showed a patella alta with an Insall-Salvati index >1.4 (Figure 1). A sleeve fracture of the right patella was seen with an intact patella tendon. The patient had previously been diagnosed with soft tissue injury to the knee at a peripheral facility and was managed conservatively. A second opinion before he came to our facility for further management stated a patella tendon tear. MRI to quantify the diagnosis could not be performed due to lack of funds. Hence a decision to operate was based on clinical and radiological findings.

 

The patella was accessed using a mid-line incision and the diagnosis was confirmed intra-operatively (Figures 2a and b). The sleeve fracture was repaired with a 2-0 mersilene ethicon fibre suture using mattress suturing technique, which we felt was a reasonably strong suture, and the construct was easy to miss.

Click to view figure 1

 

Notice the small distal fragment on the lateral view that is

secured in a backslab. A cast was maintained for 6 weeks before removal (Figure 3). The patient was discharged on an above-knee plaster of Paris with nonweight bearing for 6 weeks.