Introduction

Compartment syndrome can be a life changing consequence of injury to a limb. If not diagnosed and treated early it can lead to permanent disability. Neurovascular observations done on the ward by nursing staff, are often our early warning system to those developing compartment syndrome. But are these adequate for detecting the early signs of compartment syndrome? Our aim was to compare the quality and variability of charts across the UK major trauma network.

Coronal alignment is an important factor in long-term survival of TKA. Many implant systems are available and most aim to produce a posterior slope on the tibial component to reproduce the 7⁰ seen in the normal tibia. We hypothesized that resecting the tibial plateau with a posterior slope can introduce error in coronal plane alignment in TKA.

We used a standard saw-bones model in conjunction with a computer navigation system that is available for use in TKA (Stryker Orthopaedics). The normal protocol for preliminary referencing was followed; care was taken to identify tibial landmarks (tibial plateau reference point, true sagittal plane and transmalleolar axis). We then used a standard extramedullary alignment jig (Scorpio TKR System, Stryker Orthopaedics) with cutting blocks designed to give 0, 3, 5 and 7 degrees of posterior slope and varied the position of the alignment jig.

Variations included:

Medial rotation of the cutting block,

In all experiments, there was a greater deviation from ideal coronal alignment as the slope on the tibial cut was increased. The greatest influence was with external rotation of the distal part of the jig, which produced 3⁰ of varus at only 15⁰ of external rotation with a 7⁰ slope. Medialisation of the proximal reference point worsened this to 4.5⁰ of varus.

We have quantified the degree of coronal malalignment that can occur for different posterior slopes during tibial resection for TKA. We recommend either using a minimal slope or navigation to ensure correct implant positioning.

Correspondence should be addressed to Major M Butler RAMC, Princess Elizabeth Orthopaedic Centre, Royal Devon and Exeter Hospital, Exeter, Devon.

Background: Coronal alignment is important in long-term survival of TKA. Many systems are available; most aim to produce a posterior slope on the tibial component in order to reproduce the 7⁰ seen in the normal tibia. Some are designed to produce a bone cut with 7⁰ of slope whereas others combine the slope of the bone cut with an in-built slope on the polyethylene insert. We have investigated the theory that resecting the tibial plateau with a posterior slope can introduce error in coronal plane alignment in TKA.

Methods: We used a standard saw-bones model in conjunction with a computer navigation system that is available for use in TKA (Stryker Orthopaedics). The normal protocol for preliminary referencing was followed; care was taken to identify tibial landmarks (tibial plateau reference point, true sagittal plane and transmalleolar axis). We then used a standard extra-medullary alignment jig (Scorpio TKR System, Stryker Orthopaedics) with cutting blocks designed to give 0, 3, 5 and 7 degrees of posterior slope and varied the position of the alignment jig. Variations included:

Medial rotation of the cutting block

Results: In all experiments, there was a greater deviation from ideal coronal alignment as the slope on the tibial cut was increased. The greatest influence was from external rotation of the distal part of the jig which produced 3⁰ of varus at only 15⁰ of external rotation with a 7⁰ slope. Medialisation of the proximal reference point worsened this to 4.5⁰ of varus.

Conclusions: We have quantified the degree of coronal malalignment that can occur for different posterior slopes during tibial resection for TKA. We recommend either using a minimal slope or navigation to ensure correct implant positioning.

Between June 1988 and December 1997, 332 babies with 546 dysplastic hips were treated in the Pavlik harness for primary Developmental Dysplasia (DDH) as a product of the Southampton selective screening program. Each was managed by a strict protocol including ultrasonic monitoring of treatment within the harness. The group was prospectively studied over a mean duration of 6. 5 years (SD=2. 7y) with 89. 1% follow-up. The Acetabular Index (AI) and Centre-Edge angle of Wiberg (CEA) were measured on annual radiographs to determine the natural history of hip development following treatment in the Pavilik harness. These were compared to published normal values.

We observed a failed reduction rate of 15. 2% of all complete hip dislocations; these required alternative surgical treatment. The development of those hips of infants successfully treated in the harness showed no significant difference from the normal values of Acetabular Index for female left hips, after eighteen months of age. Of those dysplastic hips that were successfully reduced in the harness; 2. 4% exhibited persisting significant late dysplasia (CEA< 20°) and 0.2% demonstrated persistent severe late dysplasia (CEA< 15 °) All such cases could be identified at sixty months. Dysplasia was clinically deemed sufficient to merit innominate osteotomy in 0. 9% dysplastic hips treated. Avascular necrosis was noted in 1% of hips treated in the harness.

We conclude that using our protocol, successful initial treatment of DDH with the Pavlik harness appears to revert the natural history of hip development to that of the normal population. We recommend that regular radiographic surveillance up to 60 months of age constitutes safe and effective practice.

Between June 1988 and December 1997, we treated 332 babies with 546 dysplastic hips in a Pavlik harness for primary developmental dysplasia of the hip as detected by the selective screening programme in Southampton. Each was managed by a strict protocol including ultrasonic monitoring of treatment in the harness. The group was prospectively studied during a mean period of 6.5 ± 2.7 years with follow-up of 89.9%. The acetabular index (AI) and centre-edge angle of Wiberg (CEA) were measured on annual radiographs to determine the development of the hip after treatment and were compared with published normal values.

The harness failed to reduce 18 hips in 16 patients (15.2% of dislocations, 3.3% of DDH). These required surgical treatment. The development of those hips which were successfully treated in the harness showed no significant difference from the normal values of the AI for the left hips of girls after 18 months of age. Of those dysplastic hips which were successfully reduced in the harness, 2.4% showed persistent significant late dysplasia (CEA < 20°) and 0.2% persistent severe late dysplasia (CEA < 15°). All could be identified by an abnormal CEA (< 20°) at five years of age, and many from the progression of the AI by 18 months. Dysplasia was considered to be sufficient to require innominate osteotomy in five (0.9%). Avascular necrosis was noted in 1% of hips treated in the harness.

We conclude that, using our protocol, successful initial treatment of DDH with the Pavlik harness appears to restore the natural development of the hip to normal. We suggest that regular radiological surveillance up to five years of age is a safe and effective practice.