Ossicles of lumbar articular facets: normal variant or spondylolytic variant?

PURPOSE: The objective of this study was to establish the prevalence and significance of ossicles of lumbar articular facets (OLAF) in young athletes with backache diagnosed by multi-detector computed tomography (MDCT). MATERIALS AND METHODS: The MDCT examinations of the lumbar spine carried out for suspected spondylolysis on 46 consecutive symptomatic young athletes presenting to a sports injury clinic over a 1-year period were retrospectively reviewed. OLAF study included detailed correlation with the structural and morphological stress features of the posterior neural arches. This was then compared with a control group composed of 39 patients. RESULTS: Twenty-three OLAF were identified in 15 patients. Eleven of the 15 patients with ossicles had posterior element stress changes (PEST)/pars defects. In the control group, two OLAF were identified in two patients, one demonstrating PEST changes. CONCLUSION: The high prevalence of OLAF in young symptomatic athletes compared with the asymptomatic control group is indicative of stress fractures. The non-united articular process fractures should be regarded as part of the spectrum of stress-induced changes in the posterior neural arch in the same way as spondylolysis. MDCT with volumetric acquisition and multi-planar reformation is the most reliable investigation in the diagnosis of OLAF. KEY POINTS: 1) This CT study supports a traumatic aetiology for lumbar articular facets ossicles. 2) OLAF represent part of a spectrum of stress-induced changes in the posterior neural arch. 3) OLAF are associated with typical spondylolysis. 4) OLAF can be overlooked on reverse gantry angle computed tomography (RG-CT). 5) OLAF may account for some of the discrepancy between radionuclide and RG-CT studies.

Repeated exercise stress impairs volitional but not magnetically evoked electromechanical delay of the knee flexors.

The effects of serial episodes of fatigue and recovery on volitional and magnetically evoked neuromuscular performance of the knee flexors were assessed in 20 female soccer players during: (i) an intervention comprising 4 × 35 s maximal static exercise, and (ii) a control condition. Volitional peak force was impaired progressively (-16% vs. baseline: 235.3 ± 54.7 to 198.1 ± 38.5 N) by the fatiguing exercise and recovered to within -97% of baseline values following 6 min of rest. Evoked peak twitch force was diminished subsequent to the fourth episode of exercise (23.3%: 21.4 ± 13.8 vs. 16.4 ± 14.6 N) and remained impaired at this level throughout the recovery. Impairment of volitional electromechanical delay performance following the first episode of exercise (25.5%: 55.3 ± 11.9 vs. 69.5 ± 24.5 ms) contrasted with concurrent improvement (10.0%: 24.5 ± 4.7 vs. 22.1 ± 5.0 ms) in evoked electromechanical delay (P < 0.05), and this increased disparity between evoked and volitional electromechanical delay remained during subsequent periods of intervention and recovery. The fatiguing exercise provoked substantial impairments to volitional strength and volitional electromechanical delay that showed differential patterns of recovery. However, improved evoked electromechanical delay performance might identify a dormant capability for optimal muscle responses during acute stressful exercise and an improved capacity to maintain dynamic joint stability during critical episodes of loading.

Response shift in self-reported functional scores after knee microfracture for full thickness cartilage lesions.

OBJECTIVE: Our aim was to determine whether response shift (RS), a change in the internal standards of a patient, occurs in patients treated for full thickness knee cartilage defects. We have also evaluated the effect of functional scores on patient satisfaction after surgery. DESIGN: Self-administered questionnaires were used to evaluate pre- and post-operative and retrospective post-operative scores of 53 patients following knee microfracture. Patient satisfaction, Lysholm, Visual Analogue Scale (VAS) for pain and modified International Knee Documentation Committee (IKDC) scores were evaluated. RS (pre-test-then-test), unadjusted and adjusted treatment effects (UTE and ATE) and their effect sizes were calculated. RESULTS: All four functional outcome measures had a positive RS. The effect size of the RS ranged from around 0.35 for the Lysholm and IKDC2 score to over 0.9 for the VAS pain score. Gender, age, smoking status and time since follow-up did not significantly affect the RS. RS did not differ significantly between the three patient satisfaction groups (P>0.05). Post-operative Lysholm and IKDC1 scores differed most significantly between the satisfaction groups. CONCLUSIONS: All four scores had a significant shift, implying that patients thought they felt worse before the operation in retrospect than they did at the time. The traditional way of assessing treatment effect, difference between post-intervention and pre-intervention functional scores, may be confounded by change in the internal standards of the patient and should take this into account. RS did not affect the clinical interpretation in this case series. Patient-reported satisfaction after surgery is only related to post-operative scores.

A case study: Glycosaminoglycan profiles of autologous chondrocyte implantation (ACI) tissue improve as the tissue matures.

BACKGROUND: Autologous chondrocyte implantation (ACI) has been used to treat cartilage defects in thousands of patients worldwide with good clinical effectiveness 10-20years after implantation. Information concerning the quality of the repair cartilage is still limited because biopsies are small and rare. Glycosaminoglycan structure influences physiological function and is likely to be important in the long term stability of the repair tissue. The aim of this study was to assess glycosaminoglycans in ACI tissue over a two year period. METHODS: Biopsies were taken from one patient (25years old) at 12months and 20months post-ACI-treatment and from three normal cadavers (21, 22 and 25years old). Fluorophore-assisted carbohydrate electrophoresis (FACE) was used to quantitatively assess the individual glycosaminoglycans. RESULTS: At 12months the ACI biopsy had 40% less hyaluronan than the age-matched cadaveric biopsies but by 20months the ACI biopsy had the same amount of hyaluronan as the controls. Both the 12 and 20month ACI biopsies had less chondroitin sulphate disaccharides and shorter chondroitin sulphate chains than the age-matched cadaveric biopsies. However, chondroitin sulphate chain length doubled as the ACI repair tissue matured at 12months (3913Da±464) and 20months (6923Da±711) and there was less keratan sulphate as compared to the controls. CONCLUSIONS: Although the glycosaminoglycan composition of the repair tissue is not identical to mature articular cartilage its quality continues to improve with time.

The potential benefit of thermal shrinkage for lax anterior cruciate ligaments.

Radiofrequency thermal shrinkage of the anterior cruciate ligament (ACL) injured knee is a relatively recent treatment. The purpose of this study was to retrospectively analyse the results in a cohort of 32 patients with a minimum follow-up of 12 months (range 12-37 months). Cases were acute (1) or chronic (31), involving either a native or reconstructed ligament. Native ACL injuries were: lax but intact (12 + 1 acute), partial tears with remaining intact femoral attachment (4) or completely torn and attached to the posterior cruciate ligament (PCL) (6). Reconstructions were: Hamstrings (3), Bone-Patella Tendon-Bone (5) or allograft (1). We also recorded concomitant pathology, function status, Lysholm and Tegner scores and KT2000 values. The procedure was successful in limiting instability overall in 72% (23/32), and in particular 44% of reconstructed ligaments (4/9). There was no correlation of results to the treatment of co-existent pathology. The clinical scores remained high in successful cases although sporting function did reduce by follow-up. We conclude that despite these results the technique is still of value in appropriately selected, counselled and rehabilitated individuals. It is a safe technique that may avoid the necessity to proceed to reconstruction and can be considered as a planned procedure or as an adjunct to other therapy for instability at the time of arthroscopy for other pathology.

The diagnostic value of the stump impingement reflex sign for determining anterior cruciate ligament stump impingement as a cause of knee locking.

BACKGROUND: The stump impingement reflex is a subtle bounce to the knee thought to be caused by hamstring contraction when the knee is brought into extension and the torn ACL stump impinges between the distal femur and the tibial plateau. We have studied the diagnostic value of this sign. FINDINGS: From Feb 2008-Feb 2009, we audited 30 patients who underwent urgent arthroscopy for acutely locked knees. The presence of the stump impingement reflex prior to surgery was compared with the intra-operative findings. The diagnostic values of the stump impingement sign were found to be: Sensitivity 58%, Specificity 81%, Positive predictive value 70%, Negative predictive value 72% and Accuracy 71%. CONCLUSIONS: We believe that the stump impingement reflex is a specific sign for ACL stump impingement as a cause of knee locking. We recommend close inspection for this sign when examining locked knees.

Radiological findings and healing patterns of incomplete stress fractures of the pars interarticularis.

OBJECTIVE: The objective was to retrospectively record the CT and MRI features and healing patterns of acute, incomplete stress fractures of the pars interarticularis. METHOD: The CT scans of 156 adolescents referred with suspected pars interarticularis stress fractures were reviewed. Patients with incomplete (grade 2) pars fractures were included in the study. Fractures were assessed on CT according to vertebral level, location of cortical involvement and direction of fracture propagation. MRI was also performed in 72 of the 156 cases. MRI images of incomplete fractures were assessed for the presence of marrow oedema and cortical integrity. Fracture healing patterns were characterised on follow-up CT imaging. RESULTS: Twenty-five incomplete fractures were identified in 23 patients on CT. All fractures involved the inferior or infero-medial cortex of the pars and propagated superiorly or superolaterally. Ninety-two percent of incomplete fractures demonstrated either complete or partial healing on follow-up imaging. Two (8%) cases progressed to complete fractures. Thirteen incomplete fractures in 11 patients confirmed on CT also had MRI, and 92% demonstrated oedema in the pars. Ten out of thirteen fractures (77%) showed a break in the infero-medial cortex with intact supero-lateral cortex, which correlated with the CT findings. MRI incorrectly graded one case as a complete (grade 3) fracture, and 2 cases as (grade 1) stress reaction. Six fractures had follow-up MRI, 67% showed partial or complete cortical healing, and the same number showed persistent marrow oedema. CONCLUSIONS: Incomplete fracture of the pars interarticularis represents a stage of the evolution of a complete stress fracture. The direction of fracture propagation is consistent, and complete healing can be achieved in most cases with appropriate clinical management. CT best demonstrates fracture size and extent, and is the most appropriate modality for follow-up. MRI is limited in its ability to fully depict the cortical integrity of incomplete fractures of the pars, but the presence of marrow oedema on fat-saturated T2-weighted sequences is a useful means of detecting acute spondylolysis.