Abstract

Aim

This study aimed to identify risk factors for development of deep periprosthetic joint infection (PJI) in patients following surgical treatment of neck of femur fracture.

Viscosupplementation with hyaluronic acid (HA) is an established intervention for pain control in patients with mild to moderate osteoarthritis (OA) of the hip and knee. It is highly concentrated at the surface of the articular cartilage and the superficial layers of the synovial membrane. In the synovial fluid, HA acts as both a lubricant and a shock absorber. Due to the meshwork it forms with aqueous solutions, it acts as a semi-permeable barrier regulating metabolic exchanges between cartilage and the synovial fluid, and a viscoelastic shield around synoviocytes and adjacent nerve endings. Through its molecular size HA hinders the free movement of lytic enzymes and inflammatory mediators, and enhances chondrocyte metabolism. Osteoarthritis is associated with a decrease in concentration and average molecular weight of native HA in synovial fluid.

The mechanism of action of administered intra-articular HA is not completely understood, but as its clinical benefit exceeds its intra-articular presence, it is thought to perhaps induce native biosynthesis of HA and other extracellular matrix components and in particular suppress the inflammatory response and inhibit substance P, in addition to contributing to shock absorption by means of its viscoelastic properties.

Problems include inconvenience, expense and the logistical problems associated with multiple injections, injection technique and level of skill required by the administering physician, variable clinical response and adverse reactions.

In this independent, prospective, randomized trial, we compare efficacy and complications associated with treatment 100 athletes (112 knees) using durolaneTM and synvisc oneTM using the Visual Analogue Score, SF-36 V2 questionaire, and Oxford knee scores. Range of movement and absence from sporting activity is recorded at each visit. These assessments are repeated at 3, 6, 9 and 12 months. Significant improvement is seen in the VAS, SF 36 V2 and Oxford Knee Scores (p=0.01) and reduction in the use of analgesics and anti-inflammatories is seen with both products at 3 months post injection, with a significant advantage to the duro-lane group (p=0.001). At 6 months, this difference is extended even further. A small but statistical difference is noted in the time taken for the athlete to return to sporting activity following a rest period due to pain. Adverse reactions occur significantly less with the more effective product. We conclude that intra-articular HA a useful intervention in patients with mild to moderate OA of the knee, can produce sustained pain relief at 6 months, and can reduce the requirement for analgesia and anti-inflammatory medication during this time.

Embryonic chick tenocytes cultured in fixed-length three-dimensional fibrin gels synthesise a taught collagen fibril-rich extracellular matrix that closely resembles embryonic tendon (Kapacee et al., Matrix Biology, 27: 371–375, 2008). Importantly, the cells replace fibrin with parallel arrays of collagen fibrils that are able to resist pulling forces. Regenerative medicine strategies for musculoskeletal applications require the development of tissue with mechanical strength comparable to that of native tissues. How the cells generate tension is not understood and the mechanical properties and the cellular behaviour of this culture system have not been described. This project aimed to describe the morphology of cells in the tendon-like constructs and to quantitate the mechanical properties of the constructs.

Multiphoton imaging (MPI) can image deep into objects with reduced phototoxicity, allowing live-cell applications. MPI of the tendon constructs revealed that cells under tension were aligned longitudinally with the matrix. However, when tension was released the cells became rounded. The results suggested that embryonic tendon cells align along lines of force. Mechanical testing of newly-formed tendon constructs (T0), then at weekly intervals to six weeks (T7 to T42) was performed using an INSTRON^® failure-testing machine. An initial increase in ultimate tensile strength (UTS) was seen from T0 to T7 (1.023±0.031N to 1.150±1.150N, p=0.006), followed by a gradual decline at T35 to 0.350±0.043N, after which there was no further decrease. The UTS of the constructs was comparable with embryonic day 14 chick tendon. The initial increase in strength between T0 and T7 was cell dependent; constructs immersed in Triton-X 100 to remove cells were weaker than cellular constructs (1.277±0.096 versus 0.508±0.099, p< 0.001). Stress-strain plots demonstrated toe, heel, linear and failure regions that are classically observed in tendon.

The results show that embryonic tendon cells synthesise an extracellular matrix of collagen fibrils that are tensioned by the cells, and that the tendon constructs have mechanical strength comparable to in vivo generated tissue.

The research is generously supported by grants from The Wellcome Trust.

Purpose: Injury to the distal radioulnar joint can result in ulna sided wrist pain and instability. Stabilisation of the distal radioulnar ligaments described by Adams and Berger uses a tendon graft run along the anatomical course of the distal radioulnar ligaments from the lip of the radial sigmoid notch to the fovea of the ulna. The graft wraps around the ulna head and is fixed with a simple suture; this can be challenging for the surgeon and requires a considerable length of tendon. The length of graft required could be reduced by fixing the graft directly to the ulna. Alternative fixation methods when the graft is short would include bone anchors and interference screws.

We therefore compared the fixation strength achieved with simple suture, by bone anchor and by interference screw (Mini Bio-suture Tack and 3mm Biotenodesis interference screw, Arthrex, UK).

Methods: Four ulna bones were harvested along with four corresponding tendons. Tendons were divided into 2mm wide strips and run through a 3.5mm hole in the ulna. Maximum load was measured after fixing the tendon with 1) simple suture, 2) a bone anchor, and 3) an interference screw. Paired data was tested with the paired T-test and Wilcoxon test.

Results: Maximum load recorded was highest for the Mini Bio-Suture Tack bone anchor (99.28 ± 47.39) followed by the simple suture method (96.23 ± 24.14 N), and the Biotenodesis interference screw (46.90 ± 11.29). Differences approached significance when comparing simple suture fixation with interference screws (p=0.02/0.068).

Conclusions: No study has investigated the use of interference screws to secure two tendons in one graft tunnel. Previous work using a single graft and a single tendon has consistently shown that interference screws are superior to other methods of fixation. However, when performing Adam’s procedure for stabilisation of the distal radioulnar joint suturing the tendon together or using a bone anchor provide the greatest fixation strength. This might be due to loss of the interference effect when placing two grafts in the tunnel.

For any fracture classification, a high level of intraobserver reproducibility and interobserver reliability is desirable. We compare the consistency of the AO and Neer classifications for proximal humerus fractures with an assessment of the digitised radiographs of 100 fractures by 10 orthopaedic surgeons and 5 radiologists using the General Electric Picture Archiving and Communications System (PACS), allowing manipulation of the image. This process repeated 1 month later.

Reproducibility and reliability moderate for both the AO and Neer systems. Reproducibility using the AO/ ASIF system was slightly greater. The assessor’s level of experience and specialty did affect accuracy. The ability to electronically manipulate images does not improve reliability and their sole use in describing these injuries and comparing similarly classified fractures from different centres is not recommended.

Fractures of the proximal humerus are common. Most undisplaced or minimally displaced, and treated conservatively. Up to one fifth may benefit from surgery. As decisions regarding treatment are based on the fracture type, a radiological classification should be easy to use and have a high degree of reliability and reproducibility to serve as a useful discriminator, creating standards by which treatment can be recommended and outcomes compared.

Radiographs of 100 fractures of the proximal humerus selected. A true anteroposterior, scapular lateral, and axillary radiograph taken for each fracture. 10 orthopaedic surgeons and 5 radiologists recruited as assessors, including 5 specialist registrars. Each given a printed description of both Neer and AO classifications, a goniometer and ruler. The assessment preceeded by short lecture. Radiographs could be manipulated digitally for size, contrast, brightness, orientation and the negative image displayed. We did not require assessors to determine subgroups for reasons of simplicity. Reproducibility and reliability analysed using Kappa statistical methods. Coefficients for agreement compared using the Student t test incorporating the standard errors of kappa for these groups. A comparison made between radiologists and surgeons, and then consultant orthopaedic surgeons and trainees.

In each case the AO/ASIF system was statistically (p< 0.01) more accurate.

Agreement was greater for less complex (one and two part, and type A) fractures.

Level of experience produced a statistically (p< 0.01) significant difference in accuracy. Specialty did not.

Our analysis comparing the Neer and AO systems uses the largest group of assessors reviewing the largest number of radiographs reported in the literature.

We concur with others in concluding that using these systems in isolation in determining treatment and comparing results following treatment cannot be recommended

For any fracture classification, a high level of intraobserver reproducibility and interobserver reliability is desirable. We compare the consistency of the AO and Frykman classifications for distal radius fractures using digitised radiographs of 100 fractures by 15 orthopaedic surgeons and 5 radiologists using a Picture Archiving and Communications System (PACS). The process was repeated 1 month later. Reproducibility moderate for both the AO and Frykman systems, reliability only fair for both the AO and Frykman systems. In each case reproducibilty using the Frykman system was slightly greater. The assessor’s level of experience and specialty was not seen to influence accuracy. The ability to electronically manipulate images does not appear to improve reliability compared to the use of traditional hard copies, and their sole use in describing these injuries is not recommended.

These fractures are common, approximately one sixth of all fractures and the most commonly occurring fractures in adults. Their multitude of eponyms hint at the difficulty in formulating a comprehensive and useable system. The Frykman classification is most popular, but limited- does not quantify displacement, shortening or the extent of comminution. The more comprehensive AO system is limited in its complexity with 27 possible subdivisions. Computerised tomography shown to give only marginal improvement in consistency of classification.

Radiographs of 100 fractures selected. Anteroposterior and lateral view for each. 15 orthopaedic surgeons and 5 radiologists recruited as assessors, including 5 specialist registrars. Each given a printed description of Frykman and AO classifications. Radiographs could be manipulated digitally. Intra and inter-observer reproducibility analysed. A comparison made comparing reproducibility between radiologists and surgeons, consultant orthopaedic surgeons and trainees. Statistical methods; analysis involves adjustment of observed proportion of agreement between observers by correction for the proportion of agreement that could have occurred by chance. Kappa coefficients compared using the Student t test incorporating standard errors of kappa for these groups.

Median interobserver reliability was fair for both the AO (kappa = 0.31, range 0.2 to 0.38) and Frykman (kappa = 0.36, range 0.30 to 0.43) systems. Median intraobserver reproducibility was moderate for both the AO (kappa = 0.45, range 0.42 to 0.48) and Frykman (kappa = 0.55, range 0.51 to 0.57) systems. In each case the Frykman system was statistically (p< 0.01) more accurate. Level of experience, or specialty was not seen to influence accuracy (p< 0.01).

Our results demonstrate that using them in isolation in determining treatment and comparing results following treatment cannot be recommended