The management of chronic wrist pain is a challenging clinical problem. Wrist denervation aims to achieve an improvement in pain through selective neurotomy, irrespective of cause. Numerous authors have reported their experience and demonstrated a range of clinical outcomes. No studies to date have reliably identified patient populations in whom denervation surgery is most likely to succeed. We aimed to establish and investigate a new approach, combining local anaesthetic injections with a uniquely tailored functional assessment by a hand therapist, to act as a tool to identify individuals in whom surgical denervation is more likely to yield benefit. We conducted a retrospective review of 17 patients who had undergone wrist denervation procedures following our method of pre-operative assessment and selection. Patients in whom denervation was combined with other diagnostic or therapeutic surgical procedures were excluded. Each patient underwent an initial assessment by a hand therapist in which pain and functional scores were recorded using the Patient Rated Wrist Evaluation (PRWE). Further unique assessments of function were made, tailored to the functional goals and requirements of each patient. Pain scores were measured for each task. Local anaesthetic injections were then administered around the nerves considered for neurotomy and the assessments were repeated. Patients who demonstrated clear improvements in pain and function underwent surgery. Post-operative assessments of pain and function were repeated.Introduction
Methods
Negative ulnar variance, lunate shape and increased load transmission are associated with Kienbock’s disease. This may reflect trabecular alignment being more susceptible to shear forces along “fault planes” in Type 1 lunates, causing microfractures and avascular necrosis. The aim of this study was to assess the relationship between lunate bone structure, density and ulnar variance. Standard 90/90 radiographs of 22 cadaveric wrists were taken for ulnar variance and lunate shape. The lunates were harvested and routine CT scans (1mm) were taken in 22/22 in the coronal, sagittal and transverse planes. DICOM files were analysed using Mimics (Materialise, Belgium) to measure Hounsfield units. MicroCT scans (SkyScan, Belgium) (40 μm) were taken in 10/22 in the coronal plane and measured for trabecular angle at the proximal and distal joint surfaces and the ‘tilting angle’ (between scaphoid and radius joint surfaces). Data was anlaysed using one-way ANOVA tests using SPSS for Windows. Negative ulnar variance was noted in 7/22, neutral 10/22 and positive 5/22. Lunate shape according to Zapico was 0/22 Type 1, 18/22 Type 2 and 4/22 Type 3. Lunate bone density was significantly lower in the ulnar positive specimens compared to ulnar negative and neutral (p<
0.001) (fig. 1). The average trabecular angle measured 84.7° (+/− 4.5°) at the proximal and 90.3° (+/− 2.6°) at the distal joint surfaces and tilting angle was 115.7° (+/− 12.0°) (fig. 2). The 50% slice on the microCT correlated best with xray measurements of this angle. This study quantifies the previous finding that load transmission through the lunate and hence lunate bone density is related to ulnar variance and that this is higher in ulnar negative wrists. MicroCT is a useful modality to assess trabecular structure and supports the ‘fault plane’ hypothesis of Kienbock’s Disease.
Extensor Pollicis Longus (EPL) rupture occurs in 0.2 – 3% of fractures of the distal radius. The underlying mechanism is unknown. This study prospectively evaluates EPL and surrounding structures using high-resolution ultrasound (US) in patients with distal radius fracture 6 weeks after injury and correlates the findings with initial radiographic measurements. US can assess tendon size, echogenicity and peak velocity, haematoma depth and thickness of the extensor retinaculum and tendon sheath. The normal wrist was examined as a control.
Radiographic measurements – AO classification: A-32, B-12 and C-14. 76% were undisplaced fractures with dorsal tilt less than 10. Statistical analysis revealed that EPL tendon peak velocity is significantly slower on the fractured side (p=0.001). The extensor retinaculum thickness is greater (p=0.003) and the synovial sheath thickness is greater (p less than 0.001) on the fractured side. Synovial sheath thickness was also found to be significantly greater in the intra-articular fractures (p=0.03) and the undisplaced fractures (p=0.03).
As expected, the peak tendon velocity is reduced following fracture, but this is still significant at 6 weeks. This could be associated with impaired diffusion of nutrients within the synovial sheath. There is also persistent soft tissue swelling with significantly increased extensor retinaculum and synovial sheath thickness. This is a protective response to trauma, but we propose that this could interfere with the already tenuous blood supply of the EPL tendon. It could also reduce diffusion of nutrients within the tendon sheath, particularly in undisplaced fractures, where the extensor retinaculum is not torn and any increased pressure may not be dispersed. The study is ongoing with the aim to be able to identify patients at risk for EPL rupture and potentially be able to prevent it by early surgical decompression.
