Brigitte E. Scammell

Biomechanics of intra-articular and extra-articular reconstruction of the anterior cruciate ligament

Many methods of reconstruction for ACL deficiency have been described, but little is known about their biomechanical properties. We examined extra-articular (EA), intra-articular (IA) and combined (EA+IA) reconstructions in ten cadaver knees after the ACL had been ruptured by the performance of a rapid anterior drawer movement. Stability at each stage before and after rupture and reconstruction was tested by anterior drawer, Lachman, varus-valgus and tibial rotation tests. Both IA and IA+EA reconstructions restored normal stability, while EA reconstructions improved stability but did not restore it to normal. The addition of an EA procedure to an IA procedure made no difference to knee stability. We conclude that in cases of isolated ACL deficiency there is no biomechanical basis for EA reconstruction, either alone or in addition to an IA reconstruction.

Bone graft substitutes currently available in orthopaedic practice: The evidence for their use

We reviewed 59 bone graft substitutes marketed by 17 companies currently available for implantation in the United Kingdom, with the aim of assessing the peer-reviewed literature to facilitate informed decision-making regarding their use in clinical practice. After critical analysis of the literature, only 22 products (37%) had any clinical data. Norian SRS (Synthes), Vitoss (Orthovita), Cortoss (Orthovita) and Alpha-BSM (Etex) had Level I evidence. We question the need for so many different products, especially with limited published clinical evidence for their efficacy, and conclude that there is a considerable need for further prospective randomised trials to facilitate informed decision-making with regard to the use of current and future bone graft substitutes in clinical practice.

Tonic Modulation of Spinal Hyperexcitability by the Endocannabinoid Receptor System in a Rat Model of Osteoarthritis Pain

Objective To investigate the impact of an experimental model of osteoarthritis (OA) on spinal nociceptive processing and the role of the inhibitory endocannabinoid system in regulating sensory processing at the spinal level. Methods Experimental OA was induced in rats by intraarticular injection of sodium mono-iodoacetate (MIA), and the development of pain behavior was assessed. Extracellular single-unit recordings of wide dynamic range (WDR) neurons in the dorsal horn were obtained in MIA-treated rats and saline-treated rats. The levels of endocannabinoids and the protein and messenger RNA levels of the main synthetic enzymes for the endocannabinoids (N-acyl phosphatidylethanolamine phospholipase D [NAPE-PLD] and diacylglycerol lipase α [DAGLα]) in the spinal cord were measured. Results Low-weight (10 gm) mechanically evoked responses of WDR neurons were significantly (P < 0.05) facilitated 28 days after MIA injection compared with the responses in saline-treated rats, and spinal cord levels of anandamide and 2-arachidonoyl glycerol (2-AG) were increased in MIA-treated rats. Protein levels of NAPE-PLD and DAGLα, which synthesize anandamide and 2-AG, respectively, were elevated in the spinal cords of MIA-treated rats. The functional role of endocannabinoids in the spinal cords of MIA-treated rats was increased via activation of cannabinoid 1 (CB1) and CB2 receptors, and blockade of the catabolism of anandamide had significantly greater inhibitory effects in MIA-treated rats compared with control rats. Conclusion Our findings provide new evidence for altered spinal nociceptive processing indicative of central sensitization and for adaptive changes in the spinal cord endocannabinoid system in an experimental model of OA. The novel control of spinal cord neuronal responses by spinal cord CB2 receptors suggests that this receptor system may be an important target for the modulation of pain in OA.

Surgical treatment of distal radial fractures with a volar locking plate versus conventional percutaneous methods: a randomized controlled trial.

BACKGROUND The aim of this study was to compare the outcomes of displaced distal radial fractures treated with a volar locking plate with the results of such fractures treated with a conventional method of closed reduction and percutaneous wire fixation with supplemental bridging external fixation when required. Our aim was to ascertain whether the use of a volar locking plate improves functional outcomes. METHODS A single-center, pragmatic, randomized controlled trial was conducted in a tertiary care institution. One hundred and thirty patients (eighteen to seventy-three years of age) who had a displaced distal radial fracture were randomized to treatment with either a volar locking plate (n = 66) or a conventional percutaneous fixation method (n = 64). Outcome assessments were conducted at six weeks, twelve weeks, and one year. Outcomes were measured on the basis of scores on the Patient Evaluation Measure (PEM) and QuickDASH questionnaire (a shortened version of the Disabilities of the Arm, Shoulder and Hand, or DASH, Outcome Measure), EuroQol-5D (EQ-5D) scores, wrist range of motion, grip strength, and radiographic parameters. RESULTS The rate of follow-up at one year was 95%. Patients in the volar locking-plate group had significantly better PEM and QuickDASH scores and range of motion at six weeks compared with patients in the conventional-treatment group, but there were no significant differences between the two groups at twelve weeks or one year. Grip strength was better in the plate group at all time points. The volar locking plate was better at restoring palmar tilt and radial height. Significantly more patients in the plate group were driving at the end of six weeks, but this did not translate to a significant difference between groups in terms of those returning to work by that time. CONCLUSIONS Use of a volar locking plate resulted in a faster early recovery of function compared with use of conventional methods. However, no functional advantage was demonstrated at or beyond twelve weeks. Use of the volar locking plate resulted in better anatomical reduction and grip strength, but there was no significant difference in function between the groups at twelve weeks or one year. The earlier recovery of function may be of advantage to some patients. LEVEL OF EVIDENCE Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

The contribution of spinal glial cells to chronic pain behaviour in the monosodium iodoacetate model of osteoarthritic pain

BackgroundClinical studies of osteoarthritis (OA) suggest central sensitization may contribute to the chronic pain experienced. This preclinical study used the monosodium iodoacetate (MIA) model of OA joint pain to investigate the potential contribution of spinal sensitization, in particular spinal glial cell activation, to pain behaviour in this model. Experimental OA was induced in the rat by the intra-articular injection of MIA and pain behaviour (change in weight bearing and distal allodynia) was assessed. Spinal cord microglia (Iba1 staining) and astrocyte (GFAP immunofluorescence) activation were measured at 7, 14 and 28 days post MIA-treatment. The effects of two known inhibitors of glial activation, nimesulide and minocycline, on pain behaviour and activation of microglia and astrocytes were assessed.ResultsSeven days following intra-articular injection of MIA, microglia in the ipsilateral spinal cord were activated (p < 0.05, compared to contralateral levels and compared to saline controls). Levels of activated microglia were significantly elevated at day 14 and 21 post MIA-injection. At day 28, microglia activation was significantly correlated with distal allodynia (p < 0.05). Ipsilateral spinal GFAP immunofluorescence was significantly (p < 0.01) increased at day 28, but not at earlier timepoints, in the MIA model, compared to saline controls. Repeated oral dosing (days 14-20) with nimesulide attenuated pain behaviour and the activation of microglia in the ipsilateral spinal cord at day 21. This dosing regimen also significantly attenuated distal allodynia (p < 0.001) and numbers of activated microglia (p < 0.05) and GFAP immunofluorescence (p < 0.001) one week later in MIA-treated rats, compared to vehicle-treated rats. Repeated administration of minocycline also significantly attenuated pain behaviour and reduced the number of activated microglia and decreased GFAP immunofluorescence in ipsilateral spinal cord of MIA treated rats.ConclusionsHere we provide evidence for a contribution of spinal glial cells to pain behaviour, in particular distal allodynia, in this model of osteoarthritic pain. Our data suggest there is a potential role of glial cells in the central sensitization associated with OA, which may provide a novel analgesic target for the treatment of OA pain.

2009 ISSLS Prize Winner: What influence does sustained mechanical load have on diffusion in the human intervertebral disc?: an in vivo study using serial postcontrast magnetic resonance imaging.

Study Design. An in vivo study of the effects of mechanical loading on transport of small solutes into normal human lumbar intervertebral discs (IVD) using serial postcontrast magnetic resonance imaging (MRI). Objective. To investigate the influence of a sustained mechanical load on diffusion of small solutes in and out of the normal IVD. Summary of Background Data. Diffusion is an important source of disc nutrition and the in vivo effects of load on diffusion in human IVD remains unknown. Methods. Forty normal lumbar discs (on MRI) in 8 healthy volunteers were subjected to serial post contrast (Gadoteridol) 3 Tesla MRI in 2 phases. In phase 1 (control), volunteers were scanned at different time points – precontrast and 1.5, 3, 4.5, 6, and 7.5 hours postcontrast injection. In phase 2, 1 month later, the same volunteers were subjected to sustained supine loading for 4.5 hours. MRI scans were performed precontrast (preload) and postcontrast (postloading) at 1.5, 3, and 4.5 hours. Their spines were then unloaded and recovery scans performed at 6 and 7.5 hours postcontrast. In house software was used to analyze images. Results. Repeated-measures ANOVA and pairwise comparisons at different time points in the central region of the loaded disc (LD) compared to the unloaded discs (UD) revealed significantly lower signal intensity ratios (P1.5h:P3h:P4.5h<0.001:<0.001:<0.002) indicating reduction in transport rates for the LDs. Signal intensity ratios continued to rise in LD for 3 hours into recovery phase,whereas UD at the same time point showed a decrease (mean ± SD = 0.08 ± 0.08 vs. −0.21 ± 0.03). Conclusion. Sustained supine creep loading (50% body weight) for 4.5 hours retards transport of small solutes into the center of human IVD and it required 3 hours of accelerated diffusion in recovery state for LD to catch-up with diffusion in UD. The study supports the theory that sustained mechanical loading impairs diffusion of nutrients entering the disc and quite possibly accelerates disc degeneration.

Structural Associations of Symptomatic Knee Osteoarthritis

Structural changes of osteoarthritis (OA) may occur in the absence of pain. In this study, we aimed to identify histopathologic features that are associated with symptomatic knee OA.

The value of combining single photon emission computerised tomography and computerised tomography in the investigation of spondylolysis

The aim of this study was to assess the diagnostic value of combining single photon emission computerised tomography (SPECT) with reverse gantry computerised tomography (rg-CT) in the investigation of spondylolysis. Patient characteristics and imaging results in 118 patients, aged 8–44 years, with low back pain (LBP) were analysed. SPECT showed increased scintigraphic uptake in 80 patients, and spondylolysis was identified on rg-CT in 53. The Cohen Kappa ratio of 0.362 (95% CI: 0.198–0.526) suggests only fair agreement for the result of increased scintigraphic activity with the finding of spondylolysis on rg-CT. We conclude that these investigations give mutually exclusive information, which leads to four diagnostic categories. When there was increased scintigraphic activity on SPECT, 58.8% (95% CI: 48.0–69.5%) of patients had spondylolysis on rg-CT. With rest from provoking activities, these lesions may heal. We interpret the findings of increased scintigraphic activity, but no spondylolysis demonstrated on rg-CT as indicating a bone stress response. These also require rest from provoking activity to prevent a stress fracture developing. In this study, 84.2% (95% CI: 72.67–95.8%) of those patients without increased activity on SPECT had no spondylolysis identified on rg-CT. These patients may need further investigations such as magnetic resonance imaging (MRI) to diagnose pathology, which typically does not involve the posterior elements—but rest from sport may not be so important. There were five patients in our study, without increased scintigraphic activity, but in whom bilateral chronic-appearing (wide separation, smooth sclerotic bone margins) spondylolyses were identified at L5. These all were anticipated from previous plain radiographs or MRI. This group will almost certainly not heal, and if the spondylolyses are the cause of pain these vertebrae will need stabilisation by surgery if physiotherapy fails.

Clinical outcome of symptomatic unilateral stress injuries of the lumbar pars interarticularis.

Study Design. A prospective case-series study. Objective. To evaluate the results of nonoperative and operative treatment of symptomatic unilateral lumbar pars stress injuries or spondylolysis. Summary of Background Data. Most patients become asymptomatic following nonoperative treatment for unilateral lumbar pars stress injuries or spondylolysis. Surgery, however, is indicated when symptoms persist beyond a reasonable time affecting the quality of life in young patients, particularly the athletic population. Methods. We treated 42 patients (31 male, 11 female) with unilateral lumbar pars stress injuries or spondylolysis. Thirty-two patients were actively involved in sports at various levels. Patients with a positive stress reaction on single photon emission computerized tomography imaging underwent a strict protocol of activity restriction, bracing, and physical therapy for 6 months. At the end of 6 months, patients who remained symptomatic underwent a computed tomography (CT) scan to confirm the persistence of a spondylolysis. Eight patients subsequently underwent a direct repair of the defect using the modified Buck’s Technique. Baseline Oswestry Disability Index (ODI) and Short-Form-36 (SF-36) scores were compared with 2-year ODI and SF-36 scores for all patients. Results. Eight of nine fast bowlers in cricket were right-handed. The spondylolytic defect appeared on the left side of their lumbar spine. In the nonoperated group, the mean pretreatment ODI was 36 (SD = 10.5), improving to 6.2 (SD = 8.2) at 2 years. In SF-36 scores, the mean score for physical component of health (PCS) improved from 30.7 (SD = 3.2) to 53.5 (SD = 6.5) (P < 0.001), and the mean score for the mental component of health (MCS) improved from 39 (SD = 4.1) and 56.5 (SD = 3.9) (P < 0.001) at 2 years. Twenty of 32 patients resumed their sporting career within 6 months of onset of treatment, and a further 4 of 32 patients returned to sports within 1 year. The 8 patients who remained symptomatic at 6 months underwent a unilateral modified Buck’s repair. The most common level of repair was L5 (n = 5). One patient with spina bifida and a right-sided L5 pars defect remained symptomatic following direct repair. The mean preoperative ODI was 39.4 (SD = 3.6), improving to 6.4 (SD = 5.2) at the latest follow-up. The mean score of PCS (SF-36) improved from 29.6 (SD = 4.4) to 49.2 (SD = 6.2) (P < 0.001), and the mean score of MCS (SF-36) improved from 38.7 (SD = 1.9) to 54.5 (SD = 6.4) (P < 0.001). Conclusions. The increased incidence of the unilateral lumbar pars stress injuries or frank defect on the contralateral side in a throwing sports, e.g., cricket (fast bowling), may be related to the hand dominance of the individual. Nonoperative treatment for patients with a unilateral lumbar pars stress injuries or spondylolysis resulted in a high rate of success, with 81% (34/42) of patients avoiding surgery. If symptoms persist beyond a reasonable period, i.e., 6 months, and reverse gantry CT scan confirms a nonhealing defect of the pars interarticularis, one may consider a unilateral direct repair of the defect with good functional outcome. Direct repair in patients with spina bifida at the same lumbar level as the unilateral defect may be complicated by nonunion.

Reduced bone formation after exposure to organophosphates

Bone histomorphometric analysis in 24 agricultural workers with chronic organophosphate exposure showed significantly lower bone formation at tissue and cellular level than in healthy controls.