Introduction

Primary cilia are singular structures containing a microtubule-based axoneme which are believed to not only be mechanosensitive but also to co-ordinate many cell functions via signalling pathways including Hedgehog and Wnt. Primary cilia have previously been described on cells of mouse intervertebral discs (IVDs), but not in bovine or human IVDs. Our aim was to examine primary cilia in these species.

Background

Proteoglycans (PGs) have long been known to be important to the functioning of the intervertebral disc. The most common PG is aggrecan, but there are also small leucine-rich proteoglycans (SLRPs) which constitute only a small percentage of the total PGs. However, they have many important functions, including organising the collagen, protecting it from degradation and attracting growth factors to the disc. We have examined how the core proteins of these molecules vary in intervertebral discs from patients with different pathologies.

Background: The cells of the intervertebral disc must synthesise and maintain their surrounding matrix for it to function normally, providing all its physiological and mechanical properties. However, disc cells survive in an environment that most cells would not tolerate, ie with a low pH and relatively little oxygen. Cells which experience such potentially damaging conditions, including excessive heat, elicit a stress response and synthesise a range of proteins, called heat shock proteins (Hsps); these facilitate repair and survival or removal of damaged cells.

Methods and Results: We have studied Hsp production by disc cells, both in vitro and in vivo. We measured Hsps produced by bovine skin and disc cells grown in monolayer and heated up to 45°C and also immunostained human surgical discs for stress proteins, Hsp27 and Hsp72.

Disc cells responded differently to dermal fibroblasts; when freshly isolated they had a reduced or attenuated stress response and produced much less Hsp 70 than freshly isolated skin cells. After culturing in monolayer (by passage 2) all cells produced more Hsps. Human surgical discs produced varying amounts of Hsp, with most being produced by cells in herniated discs, particularly those within clusters of cells.

Conclusion: Our results suggest that intervertebral disc cells in vivo normally have a reduced stress response. Hsp production is considered to protect against damage, suggesting that the reduced response may contribute to disc degeneration and back pain. The prosurvival stress response of disc cells could provide a novel therapeutic target in patients with degenerative disc disease.

Conflict of Interest: None

Source of Funding: Wolfson Charitable Trust

The aim of our study was to assess the use of the Clavicular Hook Plate in treating acromio–clavicular joint dislocations and fractures of the distal clavicle. The prospective study was carried out at two hospitals- a teaching hospital and a district general hospital.

Between 2001 and 2004 a total of 37 patients with AC joint injuries and distal clavicle fractures were treated surgically with this device. Four of the patients had sustained a Neers Type 2 fracture of the distal clavicle, while 33 patients had acromio-clavicular joint dislocation (Rockwood Type 3 or higher). Mean age of the study group was 35.2 years. Post operatively, shoulder pendulum exercises were commenced on the second day and all patients discharged within 48 hours. During the first few weeks, we restricted shoulder abduction to 90 degrees. At the first postoperative follow up appointment at 2 weeks, average shoulder abduction was 30 degrees and forward elevation −40 degrees. This improved at 6 weeks to 85 degrees and 105 degrees respectively. The plates were removed at an average time interval of 11 weeks for the ACJ dislocations (range 8–12 weeks) and 15 weeks for the clavicle fractures (range 12–16 weeks). At three months after plate removal, we evaluated patients to measure the Visual Analogue Score(VAS) and Constant Score. The mean VAS was 1.4 (range 0–6) and the mean Constant score was 92 (range 72 to 98). Wound healing problems occurred in two patients, while two had a stress riser clavicle fracture. These had to be subsequently fixed with a Dynamic Compression Plate. One patient developed a superficial wound infection. Seven patients had problems due to impingement between the hook and the under surface of the acromion. A 45 year old female patient developed ACJ instability after plate removal. Radiographs revealed widening of the AC joint and some osteophyte formation. She went on to develop frozen shoulder which was treated with intensive physiotherapy.

The AO hook plate represents an improvement over previous implants in treating injuries around the AC Joint. However, the need for a second operation to remove the plate remains a significant problem. Complications resulting from impingement were common in our patients and represent a major drawback of this implant.

Two stainless steel ‘TriMed’ distal radial fracture reduction techniques were tested to compare the relative stability of the two in vitro for a pre-determined fracture pattern. The movement of the bony segments were plotted over time using an ARAMIS 3 dimensional non-contacting displacement mapping system (GOM mbH, Braunschweig, Germany) to give quantitative data. The data was used to calculate the relative motion of the bony segments with the aim of investigating regions of compression across the fracture line, which is thought to accelerate fracture healing, and shear between bony segments, which is detrimental to fracture healing.

Ten third generation adult radius biomechanical model Sawbones (Sawbones, Malmö, Sweden) were cut to simulate AO type C2 fractures with dorsal comminution. Five bones were plated using the TriMed fixed angle volar bearing plate and five were plated using the TriMed radius and ulnar plating technique. Samples were potted and loaded cyclically at 1 Hz via a floating scaphoid-lunate bearing onto the end of the radius at incrementally increasing loads of 100 N – 500 N with 1000 load cycles applied for each load level.

The results showed the radius and ulnar pin-plate configuration allowed greater movement of the articular surface, with relative shear motion and separation between the two segments, although the relative shear movement between the two distal segments was below 2mm, which is considered the definition of failed fixa-tion. With the volar bearing plate the two distal segments moved as single unit and compression with minimal shear was applied across the fracture line to the proximal radius. Thus the radius and ulnar plates allowed shear across all three fracture lines, while the volar plate held the two distal segments fixed relative to each other and allowed compression across the interface with the proximal radius. The ARAMIS system allowed the three dimensional motion of the bony segments to be followed, in particular the relative motion between the segments, indicating the type of healing to be expected clinically. The study demonstrated the value of ARAMIS in investigating the stability of wrist fractures fixations and can easily be adapted to investigate other orthopaedic fixation systems.

A prospective clinical investigation to determine the optimum knee flexion angle for the ‘skyline’ patellofemoral joint radiograph.

Plain radiography of the patello-femoral joint includes the axial or ‘skyline’ radiograph. The optimum knee flexion angle for making this image remains unclear.

We therefore performed a prospective clinical study in which patients underwent three skyline radiographs with knee flexion angles of 30(or minimal flexion), 50 and 90 degrees. The patients were new patients, aged between 12 and 30, presenting to a knee clinic with anterior knee pain. Two observers evaluated the radiographs, making a standardised series of measurements. Blinding was organised so that the observers were unable to use any information other than the radiographic image alone. One observer evaluated all the films on two separate occasions to allow calculation of intra- and interassessor agreement.

There were 67 knees from 46 patients. There was a high level of intra- and inter-observer agreement. There were a number of patients in which the radiographic appearance of the patello-femoral varied markedly between the different views; in all cases the abnormality was best demonstrated by the 30-degree view. There were however a number of minimal flexion views in which the film contained incomplete information because part of the patello-femoral joint was missing from the image.

We conclude that whilst a minimal flexion skyline view is the most sensitive method for the detection of patellar tilt and subluxation, not all knees can be successfully imaged at the required position. A flexible approach is therefore needed, to obtain satisfactory images at minimal flexion.