The value of preoperative grade of radiographic and histological changes in predicting pain relief after total knee arthroplasty for osteoarthritis.

PURPOSE: Many attempts with contradictory results have been made to correlate different features of OA with pain. One reason may be that pain at rest and pain with movement are seldom considered separately although the mechanisms may be quite different. Furthermore, pain ratings are subject to individual interpretation making an inter-individual comparison questionable. By instead calculating the absolute and relative changes in pain on an intra-individual level after total knee arthroplasty (TKA), we aimed at exploring a relationship between pain and radiological and histological changes. METHODS: In 69 patients undergoing TKA, preoperative radiographs and perioperative histological samples of the synovial membrane were graded for severity of osteoarthritic and inflammatory changes. The findings were related to the intensity of pain at rest and with movement both preoperatively and 18 months postoperatively according to the visual analogue scale (VAS). RESULTS: The radiographic and histological findings showed no significant correlation with the mean pre- or postoperative pain scores. Instead, change in pain with movement from pre- to postoperative was significantly related to the grade of radiographic osteoarthritis. Best pain relief by TKA was achieved in patients with severe radiographic changes. This, however, only applied to pain with movement. CONCLUSIONS: Pain at rest and pain with movement may have different mechanisms. We believe that assessing the intensity of pain at rest and pain with movement separately and considering changes in pain on an individual level will be helpful strategies in future follow-up studies and efforts aimed at explaining the mechanisms of pain in OA.

Occurrence of substance P in bone repair under different load comparison of straight and angulated fracture in rat tibia.

Substance P (SP) has been shown in vitro to stimulate both formation and resorption of bone. This seemingly contradictory observation could be explained by in vivo variations in skeletal loading and rate of bone turnover, features which may be explored during different phases of fracture healing. In 50 SD rats, the right tibia was fractured and fixed with an intramedullary pin in straight alignment and in anterior angulation resulting in a convex and concave side under different load. Fracture repair was assessed by radiography, histology, and semi-quantitative immunohistochemistry of SP nerve fiber occurrence at days 7, 21, 35, 56, and 84 post-fracture. During regeneration, days 7-35, abundant SP-nerve ingrowth was observed in the fracture callus reaching a side-symmetrical peak at day 21 in straight fractures. In angulated fractures, the SP peak was also observed at day 21 on the concave loaded side, but not until day 35 on the convex unloaded side. Each SP-peak coincided with cortical bridging. During remodeling, days 35-84, a side-symmetrical disappearance of SP-positive fibers was seen in straight fractures. The same pattern was seen on the concave loaded side of angulated fractures. However, on the convex unloaded side, where resorption now took place, SP-fibers remained until the end of the experiment. Our study suggests that neuronal SP during bone regeneration has a stimulatory role on bone formation, while during remodeling increased SP fiber density in unloaded areas may be related to bone resorption.

Site-specific CGRP innervation coincides with bone formation during fracture healing and modeling: A study in rat angulated tibia.

Sensory neuropeptide involved in local bone turnover is known, but poorly understood. In the present study, we analyze the occurrence of neuronal CGRP during healing and modeling of straight and angular tibial fractures in 74 rats. Bone healing and modeling was assessed by radiography and reinnervation by semi-quantitative immunohistochemistry method at fracture site between 1-12 weeks postfracture. The regenerating nerve fibers containing CGRP were observed in fracture callus as well as in close proximity to chondrocytes, with woven bone in both fractures already at week 1. Notably, it located predominantly on the concave side of angulated fracture in the manner of sprouting into bone from weeks 3 to 5 postfracture. In both fractures, fracture calluses peaked radiographically at week 3 postfracture. In angulated fracture, a reduction of 11% in callus thickness on convex side and an increase of 365% on concave side were noted from weeks 3 to 12. A 27-fold increase in total neuronal CGRP in straight fracture and 38-fold increases in angular fracture compared to intact bone was observed at week 3. In both types of fracture, neuronal CGRP was greater on the concave side than the convex; this difference was more pronounced in the angulated fracture. CGRP immunoreactivity clearly coincides with amount of new bone formation especially on the concave side of angulated fracture. The combined results suggest that fracture evokes an intense, localized in-growth of new nerve fibers containing CGRP, which may prove to be a prerequisite of fracture healing and modeling.

Physical activity modulates nerve plasticity and stimulates repair after Achilles tendon rupture.

In a rat model of tendon rupture using semiquantitative methodology, healing was assessed according to the diameter of newly organized collagen and the occurrence of the sensory neuropeptides (SP, CGRP) in relation to different levels of physical activity. Normally, innervation of the Achilles tendon is confined to the paratenon. After rupture new nerve fibers grow into the tendon proper, but disappear after healing. In a first experiment to establish peak tissue and nerve regeneration after rupture, tendon tissues from freely moving rats were collected consecutively over 16 weeks. A peak increase in organized collagen and nerve ingrowth was observed between week 2 to 4 post rupture. Therefore, in a second experiment week 4 was chosen to assess the effect of physical activity on tendon healing in three groups of rats, that is, wheel running, plaster treated, and freely moving (controls). In the wheel-running group, the diameter of newly organized collagen was 94% ( p = 0.001) greater than that in the plaster-treated group and 48% ( p = 0.02) greater than that in the controls. Inversely, the neuronal occurrence of CGRP in the tendon proper was 57% ( p = 0.02) lower in the wheel-running group than that in the plaster-treated group and 53% ( p = 0.02) lower than that in the controls, suggesting an earlier neuronal in-growth and disappearance in the more active group. Physical activity speeds up tendon healing, which may prove to be linked to accelerated neuronal plasticity.

Opioid peptides and receptors in joint tissues: study in the rat.

Using immunohistochemical and biochemical techniques, the occurrence of endogenous opioid peptides and their receptors in normal rat bone and joint tissues was investigated. Opioid receptors were detected, quantified, and characterized in homogenates from capsule/synovium and periosteum using radioligand binding assays. Receptor binding of the nonselective opioid [3H]naloxone to tissue homogenates was stereospecific and saturable, showing similar characteristics to that of brain tissue, although with lower binding capacities. By immunohistochemistry, the neuronal occurrence of four different enkephalins was demonstrated in synovium, bone marrow, periosteum, and juxta-articular bone, whereas no neuronal dynorphin immunoreactivity was detected. Double-staining studies disclosed that enkephalins coexisted with substance P in primary afferent fibers. The applied techniques can be used to assess changes in the distribution of endogenous opioids and their receptors in joint tissues in conditions associated with pain and inflammation. The endogenous opioid system now demonstrated might be targeted and exploited therapeutically to obtain peripheral control of symptoms in joint disorders.

Spontaneous correction of angular fracture deformity in the rat.

BACKGROUND: The different parts of long bone are known to participate in the spontaneous correction of fracture deformity. However, the relative contribution of growth plate, epiphysis and diaphysis of bone during the correction process is not clear. ANIMALS AND METHODS: We used a rat model of tibial fracture fixed with a semi-rigid intramedullary pin in anterior angulation, and evaluated the magnitude, temporal course and pertinent sites of spontaneous deformity correction by means of radiography and bone mineral uptake. RESULTS: Over a 12-week period, the mean angular deformity was corrected from 27 degrees to 11 degrees. The major portion of the correction (14 degrees of 16 degrees) occurred within 3 weeks, concomitantly with fracture healing. The angle of the proximal growth plate changed 8 degrees over the study period. The first 3 weeks were characterized by intense bone formation on the concave side of the fracture. From weeks 3-8, signs of resorption predominated on the corresponding convex side. On the concave side, the front of new bone formation in the proximal diaphysis moved in the opposite direction to that at the fracture level, so that both sites contributed to deformity correction. INTERPRETATION: We found that different sites of a diaphyseal bone fractured in angulation respond quite differently, but still in an orchestrated way to promote correction by modeling. Notably, most of the spontaneous correction occurred during the reparative phase, the major contributor being the diaphysis, not the growth plate. Compared to other reports on angulated fracture using rigid fixation and limb immobilization, our data suggest that semi-rigid fixation and early weight bearing is more efficient in enhancing not only healing, but also deformity correction.

Increase in sensory neuropeptides surrounding the Achilles tendon in rats with adjuvant arthritis.

The Achilles tendon in rats with adjuvant arthritis was analyzed by radioimmunoassay (RIA) and semi-quantitative immunohistochemistry for the occurrence of two sensory neuropeptides, substance P (SP) and calcitonin gene related peptide (CGRP), and a sensory modulating peptide, galanin (GAL). The tissue concentration of SP and CGRP in the Achilles tendon and its envelope, i.e. the paratenon and bony insertion, as assessed by RIA was increased by 22% and 71%, respectively, compared to normal controls, whereas the level of GAL was unchanged. Semi-quantitative immunohistochemistry applied to different regions of the tendon in arthritic rats disclosed an increased occurrence of SP and CGRP positive nerve fibers in the paratenon and bone tendinous junction, whereas GAL fibers were only increased at the bone tendinous junction. Notably, neither neuropeptides nor inflammatory cells were seen in the tendon proper. The increased occurrence of SP and CGRP in the tendon envelope presumably reflects inflammatory actions, whereas that of GAL implies an endogenous anti-inflammatory response. The observed SP and CGRP upregulation in the paratenon and bony insertion suggests a pathophysiological role in paratenonitis and enthesitis often seen in patients with rheumatoid arthritis. Presumably Achillodynia originates in the tendon envelope rather than the tendon proper. The observations could be used to define new pharmacological targets for mitigating symptoms from tendons in rheumatoid arthritis and possibly also in other disorders. Whether a neuronal pathogenic mechanism underlies tendon overuse disorders in non-arthritic tendinopathies and the development of degeneration, i.e. tendinosis, remains to be studied.

Combined radiology and cytology in the diagnosis of bone lesions: a retrospective study of 370 cases.

BACKGROUND: Some of the risks with open biopsy can be avoided by fine-needle aspiration biopsy. The diagnostic contribution of radiologic findings has not been systematically studied. PATIENTS AND METHODS: We retrospectively analyzed the validity of combined radiology and fine-needle aspiration cytology for the diagnosis of bone lesions in a consecutive series of 370 patients. The treatment diagnosis was based solely on radiology and cytology in 234 cases, whereas in 136 cases histopathology was also applied. RESULTS: Comparison of radiology and cytology showed diagnostic compliance in 256 cases (69%) and non-compliance in 101 (28%). 13 (3%) cases failed to yield diagnostic material for cytology. Among the 256 compliant cases, the diagnostic error rate was 1% (2 were falsely benign), whereas the corresponding rate was 17% among the 101 non-compliant cases. In the latter group, 36 cases yielded only normal cells at aspiration, out of which 20 proved to have a neoplastic lesion (8 metastases, 12 benign). The overall sensitivity of cytology alone in recognizing malignancy was 90%. The specificity was 95%. Given a malignant or benign diagnosis, the positive predictive value was 97% and the negative predictive value was 84%. INTERPRETATION: Our study suggests that a simple approach based on conventional radiography and fine-needle aspiration cytology offers a valid means of diagnosing bone lesions. Provided there is compliance between radiology and cytology, the risk of false diagnosis is around 1%.

Bone and joint neuropathy in rats with type-2 diabetes.

We have previously demonstrated that Goto-Kakizaki (GK) rats with spontaneous type-2 diabetes and peripheral neuropathy exhibit regional osteopathic changes. In the present study on 18 GK rats and 21 control Wistar rats, the occurrence of the sensory neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP), and the autonomic neuropeptide Y (NPY) was analysed in bone and joints, dorsal root ganglia and lumbar spinal cord by immunohistochemistry and radioimmunoassay (RIA). Immunohistochemistry disclosed a predominance of immunoreactivities in vessel-related nerve fibers, although some were also seen in free terminals. While SP, CGRP and NPY in periosteum, cortical bone and synovium was confined to neuronal tissue, the bone marrow in addition exhibited an abundance of NPY-positive megakaryocytes. Apart from this cellular source of NPY, the observations suggest that the three neuropeptides analysed in bone and joints are of neuronal origin. Quantification by RIA showed a significant decrease of NPY in cortical bone (-36%), bone marrow (-66%) and ankle (-29%) of GK rats. CGRP was decreased in the spinal cord (-19%) and dorsal root ganglia (-26%) but was unchanged in bone and joints, as with SP. Given the suggested anabolic role of NPY and CGRP on bone, neuropeptidergic deficit in diabetes may prove to be an important factor underlying the development of regional osteopenia.

Diagnosis of high-grade osteosarcoma by radiology and cytology: a retrospective study of 52 cases.

The diagnostic value of combined radiology and fine needle aspiration cytology (FNAC) was retrospectively assessed in a consecutive series of 52 patients with high-grade osteosarcoma. The series was divided into typical and atypical osteosarcomas according to radiological features and site. Thirty-two of 33 radiologically typical osteosarcoma cases were correctly diagnosed by cytology; one lesion was diagnosed as sarcoma NOS. Nineteen osteosarcoma cases were radiographically atypical. Six of these were diagnosed as osteosarcoma and another six as sarcoma NOS. In three cases another type of sarcoma was suggested. One case was falsely classified as benign. FNAC of three cases were non-diagnostic. Overall, the diagnostic difficulties pertained to the radiologically atypical cases. Notably, four of these also posed considerable difficulties in the histopathological assessment prompting external consultation. Our study suggests that open biopsy can be obviated in high-grade osteosarcomas exhibiting typical radiological features, i.e., in two-thirds.

Neuronal plasticity in relation to nociception and healing of rat achilles tendon.

Nerve regeneration and the occurrence of three neuropeptides; i.e. substance P (SP), calcitonin gene related peptide (CGRP) and galanin (GAL), were studied during healing of tendon rupture in the rat by semi-quantitative immunohistochemistry. The neuronal findings were related to nociception as assessed by hindpaw withdrawal latencies at thermal and mechanical tests. Experimental rupture of rat Achilles tendon--normally devoid of nerves--elicited extensive nerve ingrowth into the rupture site in the early phase of healing followed by almost complete fiber disappearance (weeks 12-16). The ingrowth of SP and CGRP positive fibers, seen already at weeks 1-2, was associated with increased nociception. Subsequently, the occurrence of GAL positive fibers at weeks 4-6 was associated with decreased nociception. An even stronger relationship to nociception during healing was observed when the rate of change in neuropeptide expression instead of the expression in absolute terms was considered, according to the "cascade" formula of SP(')+CGRP(')-GAL(').It may prove that the observed temporal occurrence of different neuropeptides reflects a role of the peripheral nervous system in regulating synchronously nociception and healing.

Peripheral quantitative computed tomography for the detection of diabetic osteopathy: a study in the Goto-Kakizaki rat.

RATIONALE AND OBJECTIVE: To assess the utility of dual energy x-ray absorptiometry (DEXA) and peripheral quantitative computed tomography (pQCT) in detecting trabecular and cortical bone changes in diabetes as a model of osteopenia. MATERIALS AND METHODS: The tibia from 10 type-2 diabetic Goto-Kakizaki (GK) rats and 10 control Wistar rats were analyzed by DEXA, pQCT, and ash weight determination. RESULTS: DEXA of GK rats showed a significant reduction in mineral content (32%) and density (24%) of the metaphysis, but not of the diaphysis. PQCT disclosed that the reduction of density predominantly pertained to the trabecular bone (reduced by 62%). Periosteal and endosteal circumferences of the diaphyses were increased and cortical thickness was unchanged leading to increased moment of inertia. CONCLUSIONS: This study suggests that in osteopathic conditions, cortical and trabecular bone should be separately examined within specific subregions to obtain relevant information. Loss of metaphyseal trabecular bone seems to be a predominant feature in diabetic rats. Moreover, there is increased moment of inertia in the diaphysis implying increased strength. These diagnostic features of diabetic osteopathy can only be assessed by pQCT. It may prove that similar changes occur in human type-2 diabetes, which could explain the susceptibility to periarticular fracture and Charcot arthropathy.

Early nerve regeneration after achilles tendon rupture--a prerequisite for healing? A study in the rat.

Nerve regeneration during healing of Achilles tendon rupture in the rat was studied by immunohistochemistry including semi-quantitative assessment. Neuronal markers for regenerating and mature fibers, ie., growth associated protein 43 (GAP-43) and protein gene product 9.5 (PGP 9.5), respectively, were analyzed at different time points (1-16 weeks) post-rupture. In the paratenon, both the ruptured and intact contralateral tendon (control) consistently exhibited immunoreactivity to the two neuronal markers. However, in the proper tendinous tissue only the ruptured tendon showed immunoreactivity to GAP-43 and PGP 9.5. This expression was seen already at week 1 post-rupture to reach a peak at week 6 followed by a successive drop till week 16. Also the occurrence of sensory and autonomic fibers according to immunoreactivity for calcitonin gene-related peptide (CGRP) and neuropeptide Y (NPY), respectively, was analyzed. CGRP-positivity was abundantly seen from weeks 2-6 in both perivascular and sprouting free nerve endings in the proper tendon tissue undergoing healing. NPY appeared later, at weeks 6-8 post-rupture around blood vessels mainly located in the surrounding loose connective tissue. Apart from a role in vasoaction (CGRP, vasodilatory; NPY, vasoconstrictory). both neuropeptides have been implicated in fibroblast and endothelial cell proliferation required for angiogenesis. The present study shows that early healing of ruptured tendons is characterized by an orchestrated, temporal appearance of nerve fibers expressing peptides with different actions. The observed pattern of neuronal regeneration and neuropeptide expression may prove to be important for normal connective tissue healing.

Alteration in endogenous opioid systems due to chronic inflammatory pain conditions.

The influence of chronic arthritic pain on two endogenous opioid peptides, dynorphin B and [Met5]enkephalin-Arg6-Phe7, and multiple opioid receptors in discrete brain, lumbar spinal cord and pituitary pools was investigated. Using radioimmunoassay and receptor binding assay, we examined the changes in regional opioid peptide levels and opioid receptor activity due to chronic inflammation in adjuvant arthritic rats. At 4 weeks post-inoculation, increased levels of immunoreactive dynorphin B and [Met5]enkephalin-Arg6-Phe7 were measured in tissues of arthritic rats compared with controls. No significant changes in mu-, delta- or kappa-opioid receptors were seen after chronic inflammation. Taken together, these results indicate that in chronic arthritis, opioid receptor changes do not follow the peptide alterations of pro-dynorphin and pro-enkephalin systems. Thus, dynamic modification and modulation of nociceptive information takes place during chronic inflammation. This supports the key role of the central nervous system in chronic inflammatory pain conditions.

Representativeness of radiologically guided fine-needle aspiration biopsy of bone lesions.

The consistency of the cellular yield as obtained by radiologically guided fine-needle aspiration biopsy (FNAB) was investigated in 29 cases with bone lesions. Aspirates from three different sites of the same lesion were analysed randomly and independently by two cytologists unaware of the clinical and radiological findings.The series was grouped cytologically into four categories: (1) benign, (2) sarcoma, (3) other malignancy, (4) non-conclusive. A lesion was considered cytologically homogenous, when all three aspirates were identically categorised. Among 29 lesions, 13 and 12, respectively, were assessed as homogeneous by the two cytologists. In the remaining lesions, heterogeneity almost exclusively pertained to the mixture of conclusive and non-conclusive aspirates. An alternative diagnosis was suggested in one case by each cytologist. Comparison of the two cytologists' assessments showed that 21 cases were compliant, i.e., no inter-observer difference in 63 out of 87 aspirates. In the remaining eight cases (24 aspirates), non-compliance was mainly due to differences between the cytologists in the ratio of conclusive versus non-conclusive aspirates. Only the analysis of one and the same aspirate resulted in two different diagnoses. A correct diagnosis was given by the cytologists in 22 and 23 cases, incorrect in two and non-conclusive in five and four, respectively.Our cytological study of bone lesions, albeit limited, suggests that true tumour heterogeneity is rare. The non-compliance between the two cytologists and the diagnostic difficulties should mainly be attributed to the blind, random approach of the study.The main problem of FNAB pertains to the high rate of non-conclusive aspirates.This, however, does not entail an increased risk of incorrect diagnosis, but rather prompts repeat FNAB.