Periprosthetic joint infection after total hip arthroplasty induces histological degeneration of the gluteus medius tendon.

Aims: A revision for periprosthetic joint infection (PJI) in total hip arthroplasty (THA) has a major effect on the patient's quality of life, including walking capacity. The objective of this case control study was to investigate the histological and ultrastructural changes to the gluteus medius tendon (GMED) in patients revised due to a PJI, and to compare it with revision THAs without infection performed using the same lateral approach. Methods: A group of eight patients revised due to a PJI with a previous lateral approach was compared with a group of 21 revised THAs without infection, performed using the same approach. The primary variables of the study were the fibril diameter, as seen in transmission electron microscopy (TEM), and the total degeneration score (TDS), as seen under the light microscope. An analysis of bacteriology, classification of infection, and antibiotic treatment was also performed. Results: Biopsy samples from the GMED from infected patients revealed a larger fibril diameter than control patients, as seen in the TEM (p < 0.001). Uninfected patients were slightly older and had their revisions performed significantly later than the infected patients. Histologically, samples from infected patients revealed significantly more vascularity (p < 0.001), the presence of glycosaminoglycans (p < 0.001), and a higher TDS (p = 0.003) than the control patients. The majority of patients had staphylococcal infections of various species. Conclusion: More histological degeneration in the GMED was found in patients undergoing THA revision surgery due to PJI than in patients undergoing THA revision surgery due to other reasons.

Histological and ultrastructural degenerative findings in the gluteus medius tendon after hip arthroplasty.

BACKGROUND: Despite gluteus medius (GMED) tendinosis being relatively common, its presence in association with hip osteoarthritis (OA) or total hip arthroplasty (THA) is not well studied. It was hypothesized that more tendon degeneration would be found in patients with OA of the hip and in those that had undergone THA than that in a control group. METHODS: One hundred patients were included between 2016 and 2019 and were included into 4 groups; the patients were undergoing revision surgery in two groups and primary THA in the other two groups; 22 patients had previously undergone primary THA through a direct lateral approach (involving sectioning of the GMED tendon), 24 patients had previously undergone primary THA through a posterior approach (leaving the GMED tendon intact), 29 patients had primary hip OA, and 25 patients who suffered a femoral neck fracture served as controls. Biopsies from the GMED tendon were obtained at the time of the primary THA or the hip revision surgery. The tendon biopsies were examined ultrastructurally and histologically. RESULTS: Ultrastructurally, the direct lateral and posterior revision groups had statistically significantly more collagen fibrils with smaller diameters compared with the fracture and primary THA groups. Moreover, the direct lateral revision group had more collagen fibrils with smaller diameters compared with the posterior revision group. Histologically, the direct lateral revision group had a higher total degeneration score (TDS) compared with the primary hip OA group. CONCLUSIONS: The GMED tendon shows more ultrastructural degeneration in patients who undergo hip revision arthroplasty than in patients with primary OA of the hip and control patients, who had suffered a femoral neck fracture. Furthermore, patients who had previously undergone primary THA through a direct lateral approach revealed more histological GMED tendon degeneration than patients who suffer primary hip OA.

More histologic and ultrastructural degenerative signs in the subscapularis tendon and the joint capsule in male patients with shoulder impingement.

PURPOSE: The purpose of the present study was to analyze biopsy samples from the subscapularis tendon and from the joint capsule from male patients with shoulder impingement syndrome (SAIS) and compare them with samples from male patients with post-traumatic recurrent shoulder instability. The hypothesis of the study was that patients with SAIS would have more histologic and ultrastructural degenerative changes in their subscapularis tendon and joint capsule than patients with post-traumatic recurrent shoulder instability. METHODS: Male patients scheduled for surgery, with either subacromial decompression or Bankart reconstruction, were included. Four biopsies from each patient were obtained from the capsule and four from the subscapularis tendon during arthroscopic surgery. The histologic characteristics and the presence of glycosaminoglycans were assessed using the light microscope, and the ultrastructure was assessed using a transmission electron microscope. RESULTS: Eight patients, median age 53 (45-74) years (p < 0.0001), were included in the impingement group, and 12 patients, median age 27 (22-48) years, were included in the instability group. The histologic assessment revealed significantly higher cellularity and total degeneration score in the capsule (p = 0.016 and p = 0.014 respectively) in patients with subacromial impingement compared with the instability patients. The corresponding finding was not made for the subscapularis tendon. The ultrastructural evaluation revealed that the instability patients had more fibrils with a large diameter (indicating less degeneration) in both the subscapularis tendon and the capsule compared with the impingement patients (p < 0.0001). CONCLUSION: Male patients with subacromial impingement have more histologic and ultrastructural degenerative changes in their shoulder compared with patients with post-traumatic recurrent shoulder instability. CLINICAL RELEVANCE: It appears that in patients with subacromial impingement, the whole shoulder joint is affected and not only the subacromial space. It is the opinion of the authors that intra-articular therapeutic injections could be tried more often in these patients. LEVEL OF EVIDENCE: III.

[Missed diagnosis of Achilles tendon ruptures most common in elderly patients]. / Missad diagnos av hälseneruptur vanligast hos äldre patienter.

We audited forty-six patients with a rupture of the Achilles tendon notified to the Swedish regulatory authority (the Health and Social Care Inspectorate) due to suspicion of malpractice. The patients' history and clinical presentation differed from those with a more classical acute rupture. The diagnostic errors were often found in patients older than 60 years, they were just as common in women as in men and the symptoms often had a subacute start. In most patients, the diagnostic errors were due to an incomplete clinical examination. More than one fourth of the patients were on medication with statins or quinolones.

Altered patterns of displacement within the Achilles tendon following surgical repair.

PURPOSE: Ultrasound speckle tracking was used to compare tendon deformation patterns between uninjured and surgically repaired Achilles tendons at 14-27-month follow-up. The hypothesis was that the non-homogenous displacement pattern previously described in uninjured tendons, where displacement within deep layers of the tendons exceeds that of superficial layers, is altered following tendon rupture and subsequent surgical repair. METHODS: In the first part of this study, an in-house-developed block-matching speckle tracking algorithm was evaluated for assessment of displacement on porcine flexor digitorum tendons. Displacement data from speckle tracking were compared to displacement data from manual tracking. In the second part of the study, eleven patients with previous unilateral surgically treated Achilles tendon rupture were investigated using ultrasound speckle tracking. The difference in superficial and deep tendon displacement was assessed. Displacement patterns in the surgically repaired and uninjured tendons were compared during passive motion (Thompson's squeeze test) and during active ankle dorsiflexion. RESULTS: The difference in peak displacement between superficial and deep layers was significantly (p < 0.01) larger in the uninjured tendons as compared to the surgically repaired tendons both during Thompson's test (-0.7 ± 0.2 mm compared to -0.1 ± 0.1 mm) and active dorsiflexion (3.3 ± 1.1 mm compared to 0.3 ± 0.2 mm). The evaluation of the speckle tracking algorithm showed correlations of r ≥ 0.89 between displacement data acquired from speckle tracking and the reference displacement acquired from manual tracking. Speckle tracking systematically underestimated the magnitude of displacement with coefficients of variation of less than 11.7%. CONCLUSIONS: Uninjured Achilles tendons display a non-uniform displacement pattern thought to reflect gliding between fascicles. This pattern was altered after a mean duration of 19 ± 4 months following surgical repair of the tendon indicating that fascicle sliding is impaired. This may affect modulation of the action between different components of the triceps surae, which in turn may affect force transmission and tendon elasticity resulting in impaired function and risk of re-rupture.

Histological Evaluation of Regenerated Semitendinosus Tendon a Minimum of 6 Years After Harvest for Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Semitendinosus (ST) and/or gracilis (G) autografts are the most used grafts for anterior cruciate ligament (ACL) surgery. The tendons have been shown to be able to regenerate but with focal areas of scar tissue in the short term. There are no long-term histological studies of the regenerated tendons. HYPOTHESIS: In the long term, the regenerated ST tendon normalizes and has a similar histology as the contralateral nonharvested tendon. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Eighteen patients (8 female, 10 male) who underwent ACL surgery using ipsilateral ST/G tendon autografts were included in this study. Percutaneous specimens were obtained from the regenerated ST tendon and the contralateral nonharvested ST tendon under ultrasonographic guidance at a median of 8.4 years (100.5 months; range, 77-129 months) after the harvest procedure. Specimens from the nonoperated side served as controls. The histology and presence of glycosaminoglycans (GAGs) were assessed using a light microscope and a semiquantitative grading system. RESULTS: Thirty-six biopsies were obtained (2 biopsies from each patient). In 5 biopsies, the amount of tissue was too small to analyze in the light microscope, and 1 patient had been operated on bilaterally and was therefore excluded. In total, 24 biopsies were included in the histological analysis. In overall terms, there were no significant differences between the regenerated and nonharvested ST tendon in terms of fiber structure, cellularity, vascularity, and level of GAGs a minimum 6 years after harvest of the ST tendon. However, 3 of the regenerated tendons displayed a loss of fiber structure. CONCLUSION: The ST tendon regenerates and may regain a histological appearance similar to that of the nonharvested contralateral tendon, as seen in this study a median of 8.4 years after harvesting. However, in some tendons, loss of fiber structure was found.

Dynamic contrast enhanced magnetic resonance imaging in chronic Achilles tendinosis.

BACKGROUND: Chronic Achilles tendinosis is a common problem. When evaluating and comparing different therapies there is a need for reliable imaging methods. Our aim was to evaluate if chronic Achilles tendinosis affects the dynamic contrast-enhancement in the tendon and its surroundings and if short-term eccentric calf-muscle training normalizes the dynamic contrast-enhancement. METHODS: 20 patients with chronic Achilles tendinopathy were included. Median duration of symptoms was 31 months (range 6 to 120 months). Both Achilles tendons were examined with dynamic contrast enhanced MRI before and after a 12- week exercise programme of eccentric calf-muscle training. The dynamic MRI was evaluated in tendon, vessel and in fat ventrally of tendon. Area under the curve (AUC), time to peak of signal, signal increase per second (SI/s) and increase in signal between start and peak as a percentage (SI%) was calculated. Pain and performance were evaluated using a questionnaire. RESULTS: In the fat ventrally of the tendon, dynamic contrast enhancement was significantly higher in the symptomatic leg compared to the contralateral non-symptomatic leg before but not after treatment. Despite decreased pain and improved performance there was no significant change of dynamic contrast enhancement in symptomatic tendons after treatment. CONCLUSION: In Achilles tendinosis there is an increased contrast enhancement in the fat ventrally of the tendon. The lack of correlation with symptoms and the lack of significant changes in tendon contrast enhancement parameters do however indicate that dynamic enhanced MRI is currently not a useful method to evaluate chronic Achilles tendinosis.

The reharvested patellar tendon has the potential for ligamentization when used for anterior cruciate ligament revision surgery.

PURPOSE: The aim of the present study was to make an in-depth clinical, radiographical, and histological evaluation of patients who underwent anterior cruciate ligament (ACL) revision surgery with reharvested central third patellar tendon autograft. METHODS: Four patients (two women and two men) underwent ACL revision surgery with reharvested patellar tendon autograft 71 (66-120) months after the primary reconstruction. The patients were followed prospectively and underwent a clinical examination and magnetic resonance imaging (MRI) at two and 10 years. Furthermore, they underwent a second-look arthroscopy involving a biopsy procedure from the reconstructed ACL 3 years after revision surgery. RESULTS: The clinical results were poor both at two and 10 years, but the knees were stable and had a firm endpoint in all four patients in the Lachman test. At the second-look arthroscopy, the graft appeared macroscopically normal in all four patients. Histologically two patients had a normal or close to normal appearance of the reconstructed ACL with no or slight increase in cellularity and vascularity. Two patients had a marked increase in cellularity and vascularity, and the findings revealed that ligamentization was present in all four patients. CONCLUSIONS: The clinical outcome 10 years after ACL revision surgery was poor in these four patients. In contrast, the reharvested patellar tendon appeared close to normal on MRI, and the second-look arthroscopy with the concomitant histological findings revealed that the grafts were viable 3 years after revision. Therefore, the reharvested patellar tendon seems to have the potential for ligamentization when used for ACL revision surgery. LEVEL OF EVIDENCE: Case series, Level IV.

Non-uniform displacement within the Achilles tendon during passive ankle joint motion.

PURPOSE: An initial step in the understanding of Achilles tendon dynamics is to investigate the effects of passive motion, thereby minimising muscle activation and reducing internal joint forces. Internal tendon dynamics during passive ankle joint motion have direct implications for clinical rehabilitation protocols after Achilles tendon surgery. The aim of this study was to test the hypothesis that tendon tissue displacement is different in different layers of the Achilles tendon during controlled passive ankle joint movements. METHODS: Ultrasound imaging was conducted on the right Achilles tendon of nine healthy recreationally active males. Standardised isokinetic passive dorsi-plantar-flexion movements were performed with a total range of motion of 35°. The tendon was divided into superficial, central and deep layers in the resulting B-mode ultrasound images viewed in the sagittal plane. A block-matching speckle tracking algorithm was applied post-process, with kernels for the measurement of displacement placed in each of the layers. RESULTS: The mean (SD) displacement of the Achilles tendon during passive dorsiflexion was 8.4 (1.9) mm in the superficial layer, 9.4 (1.9) mm in the central portion and 10.4 (2.1) mm in the deep layer, respectively. In all cases, the movement of the deep layer of the tendon was greater than that of the superficial one (P < 0.01). CONCLUSIONS: These results, achieved in vivo with ultrasonographic speckle tracking, indicated complex dynamic differences in different layers of the Achilles tendon, which could have implications for the understanding of healing processes of tendon pathologies and also of normal tendon function.

The long-term clinical and MRI results following eccentric calf muscle training in chronic Achilles tendinosis.

PURPOSE: To evaluate the long-term results following eccentric calf-muscle training in patients with chronic Achilles tendinopathy. MATERIALS AND METHODS: A total of 24 patients with chronic Achilles tendinopathy were included in a study evaluating MRI findings and clinical symptoms before and after 3 months of daily eccentric calf-muscle strength training. Median duration of symptoms was 18 months (range 6-120). Four of the patients did not perform the prescribed treatment for different reasons and were followed for 14 months. The resulting 20 treated patients completed 4.2-year (range 29-58 months) follow up. Tendon volume was evaluated by using 3D seed growing technique and signal abnormalities were visually semi-quantitatively graded. Level of pain and performance was categorized using a questionnaire completed by the patient. RESULTS: In the symptomatic treated patients, median intensity level of pain decreased from moderate/severe at time of inclusion to mild at follow up (p < 0.05). Median level of performance increased from severe impairment at time of inclusion to normal at follow up (p < 0.05). 12 out of 20 patients had raised intratendinous signal at time of inclusion compared to 2 out of 20 patients at follow up (p < 0.001). Mean tendon-volume measured 6.7 cm(3) (SD 2.0) at time of inclusion and 6.4 cm(3) (SD 2.0) at follow up (p = 0.18). The four symptomatic non-treated tendons did not improve regarding pain, performance, intratendinous signal or tendon volume. CONCLUSION: We found decreased pain, improved performance and decreased intratendinous signal both compared to index examination and immediately after the 3 months training regimen in a 4.2-year clinical and MRI follow up, in a group of patients treated with heavy loaded eccentric calf-muscle training for chronic Achilles tendinopathy. The improvements were greater at 4.2-year follow up, despite no further active treatment, than immediately after the treatment. This may indicate a good long-term prognosis for Achilles tendinosis patients.

Force in the achilles tendon during walking with ankle foot orthosis.

BACKGROUND: Ankle foot orthoses are used for postoperative treatment of Achilles tendon ruptures and decrease calf muscle electromyography activity during walking. HYPOTHESIS: Achilles tendon load decreases with increased restriction of dorsiflexion and is associated with decreased triceps surae activity. STUDY DESIGN: Controlled laboratory study. METHODS: In 8 subjects, the maximum force and rate of force development in the Achilles tendon were measured with an optic fiber technique, and the activity of the gastrocnemius, soleus, and tibialis anterior muscles was recorded using electromyography. Trial conditions were walking barefoot and wearing an ankle-foot orthoses set in 3 different positions: (1) locked at 20 degrees of plantar flexion and with free plantar flexion but restricted dorsiflexion to (2) 10 degrees plantar flexion and (3) 10 degrees dorsiflexion, respectively. The design of the ankle foot orthoses did not provide heel support when fixed in a plantarflexed position. RESULTS: Maximum Achilles tendon force was highest at the ankle-foot orthoses setting of 20 degrees plantar flexion (3.1 times body weight) and decreased to 2.1 times body weight during barefoot walking (P < .01). The rate of Achilles tendon force showed an increasing trend with less-restricted dorsiflexion. Soleus activity was 52% of mean barefoot walking activity at 3 20 degrees plantar flexion (P < .001) and then increased as dorsiflexion was less restricted. CONCLUSION: Weightbearing in ankle-foot orthoses when dorsiflexion is restricted beyond neutral may result in increased forces in the Achilles tendon compared with barefoot walking, despite reduced electromyography activity in the triceps surae and decreased rate of force development. CLINICAL RELEVANCE: If patients bear full weight in an ankle-foot orthoses locked at 20 degrees plantar flexion without heel support, the maximum force in the tendon may exceed that encountered during barefoot walking.

A histological and ultrastructural evaluation of the patellar tendon 10 years after reharvesting its central third.

PURPOSE: This study was undertaken to evaluate the histologic and ultrastructural characteristics of the patellar tendon 10 years after reharvesting its central third. HYPOTHESIS: In the long term, after its central third is reharvested, the patellar tendon does not regain a normal histological and ultrastructural appearance. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Twelve consecutive patients (4 women, 8 men) who underwent anterior cruciate ligament revision surgery using reharvested ipsilateral patellar tendon autografts were included in the study. Percutaneous biopsy samples were obtained from the central and lateral parts of the patellar tendon under ultrasonographic guidance at a median of 116 months (range, 102-127 months) after the revision procedure. Eleven biopsy specimens from asymptomatic patellar tendons obtained from open anterior cruciate ligament reconstructions served as controls. The histologic characteristics and the presence of glycosaminoglycans were assessed using a light microscope, and the ultrastructure was assessed using a transmission electron microscope. RESULTS: The histological evaluation revealed deterioration in fiber structure, increased cellularity, and increased vascularity in both the central and peripheral parts of the reharvested patellar tendon specimens compared with normal tendon specimens. No difference in the amount of glycosaminoglycans was seen in specimens from either part of the reharvested patellar tendons and the control specimens. The ultrastructural evaluation revealed that all the control specimens had a normal morphologic appearance and a compact extracellular matrix with regularly oriented collagen fibrils. Furthermore, in the control specimens, the fibril diameter was heterogeneous, with all fibril size classes present. Specimens from the central and the lateral part of the reharvested tendon displayed pathological cell appearance and a more heterogeneous extracellular matrix. The lateral specimens from the reharvested tendons also displayed all fibril size classes but with a more homogeneous distribution. In the central specimens, the largest fibril size class was absent. CONCLUSION: Ten years after its central third was reharvested for anterior cruciate ligament revision surgery, the patellar tendon had not normalized in terms of its histological and ultrastructural appearance.

The temporal responses of protein synthesis, gene expression and cell signalling in human quadriceps muscle and patellar tendon to disuse.

We hypothesized that rates of myofibrillar and patellar tendon collagen synthesis would fall over time during disuse, the changes being accompanied in muscle by decreases in focal adhesion kinase (FAK) phosphorylation and in gene expression for proteolytic enzymes. We studied nine men (22 +/- 4 years, BMI 24 +/- 3 kg m(-2) (means +/- s.d.) who underwent unilateral lower leg suspension for 23 days; five were studied between 0 and 10 days and four between 10 and 21 days. Muscle and tendon biopsies were taken in the postabsorptive state at days 0, 10 and 21 for measurement of protein synthesis, gene expression and protein phosphorylation. Muscle cross-sectional area decreased by 5.2% at 14 days and 10.0% (both P < 0.001), at 23 days, i.e. 0.5% day(-1), whereas tendon dimensions were constant. Rates of myofibrillar protein synthesis fell (P < 0.01) from 0.047% h(-1) at day 0 to 0.022% h(-1) at 10 days without further changes. Tendon collagen synthetic rates also fell (P < 0.01), from 0.052 to 0.023% h(-1) at 10 days and then to 0.010% h(-1) at 21 days. FAK phosphorylation decreased 30% (P < 0.01) at 10 days. No changes occurred in the amounts/phosphorylation of PKB-P70s6k-mTOR pathway components. Expression of mRNA for MuRF-1 increased approximately 3-fold at 10 days without changes in MAFbx or tripeptidyl peptidase II mRNA, but all decreased between 10 and 21 days. Thus, both myofibrillar and tendon protein synthetic rates show progressive decreases during 21 days of disuse; in muscle, this is accompanied by decreased phosphorylation of FAK, with no marked increases in genes for proteolytic enzymes.

Ultrastructural collagen fibril alterations in the patellar tendon 6 years after harvesting its central third.

BACKGROUND: Clinically, donor site problems are common, even in the long term after anterior cruciate ligament reconstruction using patellar tendon autograft. However, there is a lack of knowledge in terms of the mid- and long-term ultrastructural appearance of the previously harvested tendon in humans. HYPOTHESIS: The patellar tendon does not regain normal ultrastructure 6 years after harvesting its central third and leaving the defect open. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Thirteen patients were included in the study. Biopsy specimens were obtained from the central and lateral thirds of the patellar tendon under ultrasound guidance 71 months (range, 68-73 months) after the reconstruction. Ten biopsy specimens from other subjects with asymptomatic patellar tendons served as controls. The sections were evaluated using transmission electron microscopy. Longitudinal sections were used for morphological evaluation, and the fibril diameter was measured on the transverse sections and grouped into 5 diameter classes. RESULTS: All control specimens were found to have a compact extracellular matrix with regularly oriented collagen fibrils. Specimens from the lateral part of the harvested tendons displayed a more heterogeneous extracellular matrix. In 3 specimens, the extracellular matrix was different from that of the control specimens. Specimens from the central part of the harvested tendons displayed an even more heterogeneous extracellular matrix, with 8 specimens judged as heterogeneous. The fibril diameter in control specimens displayed the most heterogeneous pattern, and all 5 fibril classes were present. All fibril classes were found in the lateral biopsy specimens from the previously harvested tendons, but the 2 smallest fibril classes (0-30 and 31-60 nm) were significantly more dominant compared with control specimens (P < .0001). In the central specimens from the previously harvested tendons, only the 3 smallest size classes were found (P < .0001 vs controls). CONCLUSION: Six years after harvesting its central third and leaving the defect open, the patellar tendon revealed a "more heterogeneous matrix" with changes in ultrastructural morphology and relative fibril diameter distribution compared with normal control tendon.

Reliability in the assessment of tendon volume and intratendinous signal of the Achilles tendon on MRI: a methodological description.

The purpose is to introduce a method for accurately and objectively evaluating volume and mean intratendinous signal within the Achilles tendon using MRI. We prospectively studied MRI from 33 patients with chronic Achilles tendinosis (20 males and 13 females) with a median age of 52 years (range 29-70). In all patients, both Achilles tendons were investigated with T1-WI as well as PD-WI MRI. Thus, 66 Achilles tendons were evaluated in the study. Tendon volume and mean intratendinous signal were evaluated using a computerized 3-D seed-growing technique. In general, the computerized 3-D seed-growing technique resulted in an excellent overall observer reliability of the MRI-measurements. The reliability (R) for tendon volume measurements was highest for the T1-WI sequence (R=97.9%). For the mean intratendinous signal, the PD-WI sequence showed the highest reliability (R=88.1%). The same pattern was present when we studied the coefficient of variation (CV). For the CV, lower figures indicate more reliable estimates. CV was 4.9% for tendon volume and 8.9% for mean intratendinous signal. In conclusion, it could be said that a computerized 3-D seed-growing technique to monitor and evaluate the volume of the Achilles tendon and mean intratendinous signal, using MRI, shows an overall excellent reliability regarding inter- as well as intra-observer reliability.

Acute rupture of the Achilles tendon.

Achilles tendon ruptures are common, and their incidence is increasing. The evidence for best management is controversial, and, in selected patients, conservative management and early mobilization achieves excellent results. Surgery is associated with an increased risk of superficial skin breakdown; however, modern techniques of percutaneous repair that are performed under local anesthesia and followed by early functional rehabilitation are becoming increasingly common, and should be considered when managing such patients.

A long-term serial histological evaluation of the patellar tendon in humans after harvesting its central third.

It is previously known that the patellar tendon does not normalise histologically in the short term after harvesting its central third. The aim of the study was to obtain long-term serial biopsies from the central and peripheral parts of the patellar tendon after the harvesting procedure. Our hypothesis was that in the long term after harvesting its central third, the patellar tendon does not regain normal histological appearance. Seventeen consecutive patients, who had undergone anterior cruciate ligament reconstruction using patellar tendon autografts, were included. Percutaneous biopsies were obtained under ultrasonographic guidance 27 (24-29) months and 71 (68-73) months after the index procedure, respectively. The sections were stained with haematoxylin and eosin. The biopsies were evaluated using light microscope. Both at 27 months and 71 months, the fibre structure was deteriorated and the vascularity and cellularity were increased compared with normal tendon. This was seen in both the central and peripheral parts of the tendon. In conclusion, nearly 6 years after harvesting its central third, the patellar tendon had still not normalised histologically, neither in the central nor peripheral parts of the tendon.

Immediate Achilles tendon response after strength training evaluated by MRI.

PURPOSE: To evaluate the tendon response after acute strength training in chronic Achilles tendinosis using magnetic resonance imaging (MRI). METHODS: Twenty-two patients (44 Achilles tendons, 15 males, 8 patients with bilateral symptoms) with a median age of 45 yr (range 28-57 yr) were included in the study. In all patients, both Achilles tendons were examined with MRI before and immediately after a standardized training program. The most painful side underwent 6 sets and 15 repetitions of heavy-loaded eccentric training. The contralateral tendons underwent only concentric loading during the training program. The tendon volume and the intratendinous signal were evaluated and calculated by MRI using a seed-growing technique. RESULTS: The immediate response of eccentric loading on the symptomatic tendons resulted in a 12% increase of the tendon volume, evident on T2-WI, from 7.8 +/- 2.0 to 8.8 +/- 2.7 cm3 (P < 0.001), and a 31% increase of the intratendinous signal evident on PD-WI, from 221 +/- 74 to 278 +/- 78 signal units (SU) (P < 0.001). The corresponding sequences on the contralateral concentrically loaded tendons showed an increase of 17% of tendon volume, from 6.1 +/- 1.5 to 7.0 +/- 1.6 cm3 (P < 0.001), and an increase of 27% of the intratendinous signal, from 170 +/- 55 to 211 +/-57 SU (P < 0.001). There was no significant difference of the mean of the increased tendon volume and the intratendinous signal between the eccentrically heavily loaded symptomatic tendons and the concentrically loaded contralateral tendons. CONCLUSIONS: Both eccentric and concentric loading of the Achilles tendon resulted in increased total tendon volume and intratendinous signal. This increase may be explained by a higher water content and/or hyperemia in the Achilles tendon during and/or immediately after strength training of the gastrocnemius-soleus complex.

Eccentric training of the gastrocnemius-soleus complex in chronic Achilles tendinopathy results in decreased tendon volume and intratendinous signal as evaluated by MRI.

BACKGROUND: Satisfactory treatment results have been reported after eccentric calf muscle strength training in patients with chronic Achilles tendinopathy. HYPOTHESIS: Magnetic resonance imaging may be a useful adjunct in the evaluation of the effect of 3 months of eccentric calf muscle strength training. STUDY DESIGN: Prospective cohort study. METHODS: Using magnetic resonance imaging, the Achilles tendons were investigated in 25 patients (16 men and 9 women) ranging in age from 28 to 70 years (median, 51 years) before and after training. Five different magnetic resonance imaging sequences were used. Tendon volume and mean intratendinous signal were calculated using a new seed-growing technique showing 99.3% and 96.6% intraobserver reliability, respectively. The clinical outcome was categorized according to pain level and performance using a questionnaire completed by the patient. RESULTS: The eccentric training resulted in a 14% (mean) decrease of tendon volume measured on T1-weighted images, from 6.6 +/- 3.1 cm3 to 5.8 +/- 2.3 cm3 (P < .05). The intratendinous signal in the symptomatic Achilles tendon measured on proton density-weighted images decreased 23% (mean), from 227 +/- 77 signal units to 170 +/- 83 signal units (P < .05). The gadolinium contrast agent-enhanced images did not add further value compared with other sequences. CLINICAL OUTCOME: The clinical outcome was categorized as excellent in 10, good in 3, fair in 5, and poor in 8 patients. The Delta signal correlated significantly with the pain level (P < .05). CONCLUSIONS: Eccentric training resulted in decreased tendon volume and intratendinous signal and was correlated with an improved clinical outcome. Magnetic resonance imaging techniques can be used as an adjunct to clinical evaluation by monitoring morphologic effects in clinical treatment studies of Achilles tendinopathy.

Mechanism of accumulation of cholesterol and cholestanol in tendons and the role of sterol 27-hydroxylase (CYP27A1).

OBJECTIVE: Tendon xanthomas are deposits of lipids and connective tissue commonly found in hypercholesterolemic patients. Macrophages are likely to be responsible for the lipid accumulation. Normolipidemic patients with the rare disease cerebrotendinous xanthomatosis, lacking the enzyme sterol 27-hydroxylase (CYP27A1), develop prominent xanthomas in tendons and brain containing both cholestanol and cholesterol, with a cholestanol:cholesterol ratio higher than that in the circulation. Because of its ability to convert cholesterol into polar metabolites that leave the cells faster, CYP27A1 has been suggested to be an antiatherogenic enzyme. The hypothesis was tested that tendons contain CYP27A1 that may be of importance for the normal efflux of both steroids. METHODS AND RESULTS: Western blotting and combined gas chromatography-mass spectrometry showed that human tendons contain significant amounts of CYP27A1 and its product, 27-hydroxycholesterol. Immunohistochemistry showed that CYP27A1 is present in macrophages and tenocytes. The tendons also contained cholestanol, with a cholestanol:cholesterol ratio slightly higher than that in the circulation. Recombinant human CYP27A1, and cultured human macrophages containing this enzyme, had similar activity toward cholesterol and cholestanol. After loading of macrophages with labeled cholesterol and cholestanol, there was an efflux of these steroids in both unmetabolized and 27-oxygenated form, resulting in a significant cellular accumulation of cholestanol compared with cholesterol. CONCLUSION: The results are consistent with the possibility that CYP27A1 is of importance for the efflux of both cholesterol and cholestanol from tendons.