Evaluation of hop performance in children with anterior cruciate ligament reconstruction using healthy reference data: A cross-sectional study.

BACKGROUND: Hop performance evaluation in children after anterior cruciate ligament (ACL) reconstruction may benefit from comparison to healthy controls. Thus, the purpose was to investigate the hop performance in children one year after ACL reconstruction with a comparison to healthy controls. METHODS: Hop performance data from children with ACL reconstruction one year post-surgery and healthy children were compared. Four one-legged hop test data were analyzed: 1) single hop (SH), 2) 6 m timed hop (6 m-timed), 3) triple hop (TH), and 4) cross-over hop (COH). Outcomes were the best result (longest/fastest hop) from each leg and limb asymmetry. Differences in hop performance between-limbs (operated versus non-operated) and between-groups were estimated. RESULTS: 98 children with ACL reconstruction and 290 healthy children were included. Few statistically significant group differences were observed. Girls with ACL reconstruction outperformed healthy controls in two tests on the operated leg SH, COH) and in three tests on the non-operated leg (SH, TH, COH). However, the girls performed 4-5% worse on the operated leg when compared to the non-operated leg in all hop tests. No statistically significant between-group differences in the limb asymmetry were found. CONCLUSION: The hop performance in children with ACL reconstruction one year post-surgery was largely comparable to the level of healthy controls. Despite this, we cannot exclude that neuromuscular deficits exist among the children with ACL reconstruction. The inclusion of a healthy control group for evaluating hop performance evoked complex findings regarding the ACL reconstructed girls. Thus, they may represent a selected group.

Remodeling of muscle fibers approaching the human myotendinous junction.

The myotendinous junction (MTJ) is at high risk of strain injuries, due to high amounts of energy that is transferred through this structure. The risk of strain injury is significantly reduced by heavy resistance training (HRT), indicating a remodeling capacity of MTJ. We investigated the degree of remodeling of muscle fibers near the human MTJ. In 8 individuals, samples were taken from the semitendinosus and gracilis MTJ and they were stained immunohistochemically for myonuclei (DAPI), fibroblasts (TCF7L2), and satellite cells (CD56). A high portion of the muscle fibers adjacent to the MTJ contained a centrally located myonucleus (47 ± 8%, mean ± SD) and half of the muscle fibers were CD56 positive. The number of satellite cells and fibroblasts were not higher than what has previously been reported from muscle bellies. The immunohistochemical findings suggest that the rate of remodeling of muscle fibers near the MTJ is very high. The finding that there was no increased number of satellite cells and fibroblasts could be explained as a dynamic phenomenon. The effect of HRT should be evaluated in a randomized setting.

Composition and adaptation of human myotendinous junction and neighboring muscle fibers to heavy resistance training.

The myotendinous junction (MTJ) is a common site of strain injury and yet understanding of its composition and ability to adapt to loading is poor. The main aims of this study were to determine the profile of selected collagens and macrophage density in human MTJ and adjoining muscle fibers, and to investigate whether heavy exercise loading would alter this profile. Fifteen individuals scheduled for anterior cruciate ligament repair surgery were randomized into three groups: control, acute or 4 weeks heavy resistance training. MTJ samples were collected from the semitendinosus and gracilis muscles and were sectioned and stained immunohistochemically for collagen types I, III, VI, XII, XIV, XXII, Tenascin-C and CD68. Macrophage density and distribution was evaluated and the amount of each collagen type in muscle and MTJ was graded. Collagen XXII was observed solely at the MTJ, while all other collagens were abundant at the MTJ and in muscle perimysium or endomysium. The endomysial content of collagen XIV, macrophages and Tenascin-C increased following 4 weeks of training. These findings illustrate the heterogeneity of collagen type composition of human MTJ. The increase in collagen XIV following 4 weeks of training may reflect a training-induced protection against strain injuries in this region.

Potential serious bias in National Clinical Databases with low degree of reported follow-up.

We identified reasons for the low follow-up rate in the Danish Knee ligament Reconstruction Register (DKRR) and evaluated its influence on the data quality. All 946 primary ACL-reconstructed patients in the Capital Region of Denmark during 2012 were identified in the databases of 8 participating hospitals. We studied the patient files and compared them to figures reported to the DKRR. 92.5% of the operated patients was registered in DKRR. The 1-year follow-up rate reported to DKRR was 33.4%, and 14.5% filled in patient reported outcomes (KOOS and Tegner) at 1 year. Only 65% had actually been invited for follow-up, but among the patients who had been invited 91% were seen. 41% of existing follow-up data was not reported. Contemporary technology and structured motivation should be introduced to increase validity of data in national clinical databases. Follow-up >90% in the DKRR is realistic if patents are invited and reported. The unreported data is potentially a serious bias. It is suggested that data from clinics with low follow-up should not be used in studies involving outcomes based on national databases because of risk of bias.

The role of the anterolateral ligament in ACL insufficient and reconstructed knees on rotatory stability: A biomechanical study on human cadavers.

Studies suggest that the anterolateral ligament (ALL) is important for knee stability. The purpose was to clarify ALL's effect on rotatory and anterior-posterior stability in the anterior cruciate ligament (ACL)-insufficient and reconstructed knees and the effect of reconstruction of an insufficient ALL. Eighteen cadaveric knees were included. Stability was tested for intact (+ALL), detached (-ALL) and reconstructed (+ reALL) ALL, with ACL removed (-ACL) and reconstructed (+ACL) in six combinations. All were tested in 0, 30, 60, and 90 °C flexion. Anterior-posterior stability was measured with a rolimeter. Rotation with a torque of 8.85 Nm was measured photographically. The ALL was well defined in 78% of knees. ACL reconstruction had a significant effect on anterior-posterior stability. Detaching the ALL had a significant effect on internal rotatory stability and on anterior-posterior stability in ACL-insufficient knees. Reconstruction of ACL and ALL reestablished knee stability. The appearance of the ALL was not uniform. The ALL was an internal rotational stabilizer. Anatomical ALL reconstruction in combination with ACL reconstruction could reestablish stability. ALL reconstruction might be considered in patients with combined ACL and ALL tears, but the clinical effect should be established in a controlled clinical study.

The human myotendinous junction: an ultrastructural and 3D analysis study.

The myotendinous junction (MTJ) is a specialized structure in the musculotendinous system, where force is transmitted from muscle to tendon. Animal models have shown that the MTJ takes form of tendon finger-like processes merging with muscle tissue. The human MTJ is largely unknown and has never been described in three dimensions (3D). The aim of this study was to describe the ultrastructure of the human MTJ and render 3D reconstructions. Fourteen subjects (age 25 ± 3 years) with isolated injury of the anterior cruciate ligament (ACL), scheduled for reconstruction with a semitendinosus/gracilis graft were included. Semitendinosus and gracilis tendons were stripped as grafts for the ACL reconstruction. The MTJ was isolated from the grafts and prepared for transmission electron microscopy (TEM) and focused ion beam/scanning electron microscopy. It was possible to isolate recognizable MTJ tissue from all 14 patients. TEM images displayed similarities to observations in animals: Sarcolemmal evaginations observed as finger-like processes from the tendon and endomysium surrounding the muscle fibers, with myofilaments extending from the final Z-line of the muscle fiber merging with the tendon tissue. The 3D reconstruction revealed that tendon made ridge-like protrusions, which interdigitiated with groove-like indentations in the muscle cell.

Dimensionality of the Knee Numeric-Entity Evaluation Score (KNEES-ACL): a condition-specific questionnaire.

The benefit of anterior cruciate ligament (ACL) reconstruction has been questioned based on patient-reported outcome measures (PROMs). Valid interpretation of such results requires confirmation of the psychometric properties of the PROM. Rasch analysis is the gold standard for validation of PROMs, yet PROMs used for ACL reconstruction have not been validated using Rasch analysis. We used Rasch analysis to investigate the psychometric properties of the Knee Numeric-Entity Evaluation Score (KNEES-ACL), a newly developed PROM for patients treated for ACL deficiency. Two-hundred forty-two patients pre- and post-ACL reconstruction completed the pilot PROM. Rasch models were used to assess the psychometric properties (e.g., unidimensionality, local response dependency, and differential item functioning). Forty-one items distributed across seven unidimensional constructs measuring impairment, functional limitations, and psychosocial consequences were confirmed to fit Rasch models. Fourteen items were removed because of statistical lack of fit and inadequate face validity. Local response dependency and differential item functioning were identified and adjusted. The KNEES-ACL is the first Rasch-validated condition-specific PROM constructed for patients with ACL deficiency and patients with ACL reconstruction. Thus, this instrument can be used for within- and between-group comparisons.

Development of the Knee Numeric-Entity Evaluation Score (KNEES-ACL): a condition-specific questionnaire.

Patient-related outcome measures (PROMs) are commonly used to gauge treatment effects in patients with anterior cruciate ligament (ACL) deficiency. Valid measures of specific conditions depend on relevant item content. While item content can be derived either from clinicians (face validity) or from patients, item relevance and comprehensiveness can only be confirmed by the patient (content validity). Focus group and single interviews were conducted with patients' pre- and post-ACL reconstruction in order to construct a condition-specific PROM for the target patients. One hundred fifty-seven items from a previously conducted literature search were used as a basis for content genesis. Content saturation was achieved after three focus groups and seven single interviews. Thirty-eight items from the literature search were directly endorsed, and five modified items were endorsed. Twelve new item themes with verbatim content emerged. Thus, a 55-item pilot PROM consisting of six conceptual domains was assembled. We have constructed a condition-specific PROM for measurement of surgical and non-surgical treatment effects on ACL deficiency. The instrument possesses face and content validity. A pilot survey to assess the psychometric properties will be performed using Rasch measurement theory.

Ultrasound-guided continuous suprascapular nerve block for adhesive capsulitis: one case and a short topical review.

We present a case with an ultrasound-guided (USG) placement of a perineural catheter beneath the transverse scapular ligament in the scapular notch to provide a continuous block of the suprascapular nerve (SSN). The patient suffered from a severe and very painful adhesive capsulitis of the left shoulder secondary to an operation in the same shoulder conducted 20 weeks previously for impingement syndrome and a superior labral anterior-posterior tear. Following a new operation with capsular release, the placement of a continuous nerve block catheter subsequently allowed for nearly pain-free low impact passive and guided active mobilization by the performing physiotherapist for three consecutive weeks. This case and a short topical review on the use of SSN block in painful shoulder conditions highlight the possibility of a USG continuous nerve block of the SSN as sufficient pain management in the immediate post-operative period following capsular release of the shoulder. Findings in other painful shoulder conditions and suggestions for future studies are discussed in the text.

Early osteoarthritis and microdialysis: a novel in vivo approach for measurements of biochemical markers in the perisynovium and intraarticularly.

The microdialysis technique was evaluated as a possible method to obtain local measurements of biochemical markers from knee joints with degenerative changes. Seven patients scheduled for arthroscopy of the knee due to minor to moderate degenerative changes had microdialysis catheters inserted under ultrasonographic guidance, intraarticularly and in the synovium-close tissue. Catheters were perfused at a rate of 2 µl/min for approximately 100 min with a Ringer solution containing radioactively labeled glucose, and the positions of the catheters were later visualized during arthroscopy. All intraarticular catheters and 6/7 subsynovial catheters were positioned correctly. Relative recovery (RR) was intraarticularly 0.64 ± 0.02 (mean ± SEM) and synovium-close 0.54 ± 0.06. Mean values of cartilage oligomeric matrix protein (COMP), aggrecan and glucosyl-galactosyl-pyridinoline in the intraarticular dialysates were 18.1 ± 7.0 U/l, 243.6 ± 108.6 ng/ml and 108.0 ± 29.0 pmol/ml, respectively. COMP and glucosyl-galactosyl-pyridinoline concentrations were significantly higher intraarticularly compared to perisynovial tissue (P < 0.05), whereas for aggrecan, no significant difference was found (P = 0.06). The microdialysis method can be used for intraarticular and subsynovial determination of metabolites in human knees at these sites. The present methodology displays a potential for future studies of simultaneous biochemical changes within and around joints.

From mechanical loading to collagen synthesis, structural changes and function in human tendon.

The adaptive response of connective tissue to loading requires increased synthesis and turnover of matrix proteins, with special emphasis on collagen. Collagen formation and degradation in the tendon increases with both acute and chronic loading, and data suggest that a gender difference exists, in that females respond less than males with regard to an increase in collagen formation after exercise. It is suggested that estrogen may contribute toward a diminished collagen synthesis response in females. Conversely, the stimulation of collagen synthesis by other growth factors can be shown in both animal and human models where insulin-like growth factor 1 (IGF-I) and transforming growth factor-beta-1 (TGF-beta-1) expression increases to accompany or precede an increase in procollagen expression and collagen synthesis. In humans, it can be demonstrated that an increase in the interstitial concentration of TGF-beta, PGE2, IGF-I plus its binding proteins and interleukin-6 takes place after exercise. The increase in IGF-I expression in tendon includes the isoform that has so far been thought only to exist in skeletal muscle (mechano growth factor). The increase in IGF-I and procollagen expression showed a similar response whether the tendon was stimulated by concentric, isometric or eccentric muscle contraction, suggesting that strain rather that stress/torque determines the collagen-synthesis stimulating response seen with exercise. The adaptation time to chronic loading is longer in tendon tissue compared with contractile elements of skeletal muscle or the heart, and only with very prolonged loading are significant changes in gross dimensions of the tendon observed, suggesting that habitual loading is associated with a robust change in the size and mechanical properties of human tendons. An intimate interplay between mechanical signalling and biochemical changes in the matrix is needed in tendon, such that chemical changes can be converted into adaptations in the morphology, structure and material properties.

Traumatic knee extension deficit (the locked knee): can MRI reduce the need for arthroscopy?

In the present study we investigated the validity of magnetic resonance imaging (MRI) and arthroscopy in knees with acute, traumatic extension deficit (the "locked knee"), and evaluated whether arthroscopy of knees with no mechanical pathology could be avoided by MRI evaluation. The study consisted of 50 patients who had an acute, traumatic extension deficit of the knee. All patients were submitted to MRI prior to arthroscopy. Following MRI and surgery, standardized forms were filled out, attempting to objectify the findings. The orthopaedic surgeon was not aware of the MRI result prior to surgery. Evaluating MRI, all grade-3 meniscal lesions were considered able to cause a mechanical block as well as acute partial or total anterior cruciate ligament (ACL)-ruptures. ACL-ruptures with an old appearance were not considered able to cause locking. Assuming that arthroscopy was the gold standard, the following results were calculated for the overall appearance of a lesion able to cause locking: Positive predictive value = 0.85, negative predictive value = 0.77, sensitivity = 0.95, specificity = 0.53. Two knees were erroneously evaluated with no mechanical locking at MRI (one bucket-handle lesion and one pathological synovial plica). MRI of the knee with acute, traumatic extension deficit is in the acute or subacute phase a safe method to identify the patients that have a mechanical reason for locking and therefore can benefit from arthroscopic treatment.

Collagen synthesis in human musculoskeletal tissues and skin.

We have developed a direct method for the measurement of human musculoskeletal collagen synthesis on the basis of the incorporation of stable isotope-labeled proline or leucine into protein and have used it to measure the rate of synthesis of collagen in tendon, ligament, muscle, and skin. In postabsorptive, healthy young men (28 +/- 6 yr) synthetic rates for tendon, ligament, muscle, and skin collagen were 0.046 +/- 0.005, 0.040 +/- 0.006, 0.016 +/- 0.002, and 0.037 +/- 0.003%/h, respectively (means +/- SD). In postabsorptive, healthy elderly men (70 +/- 6 yr) the rate of skeletal muscle collagen synthesis is greater than in the young (0.023 +/- 0.002%/h, P < 0.05 vs. young). The rates of synthesis of tendon and ligament collagen are similar to those of mixed skeletal muscle protein in the postabsorptive state, whereas the rate for muscle collagen synthesis is much lower in both young and elderly men. After nutrient provision, collagen synthesis was unaltered in tendon and skeletal muscle, remaining at postabsorptive values (young: tendon, 0.045 +/- 0.008%/h; muscle, 0.016 +/- 0.003%/h; elderly: muscle, 0.024 +/- 0.003%/h). These results demonstrate that the rate of human musculoskeletal tissue collagen synthesis can be directly and robustly measured using stable isotope methodology.

Diagnosing patients with longstanding shoulder joint pain.

OBJECTIVE: To examine the interobserver agreement of commonly used clinical tests and diagnoses in patients with shoulder pain, and the accuracy of these tests and ultrasonographic findings in comparison with arthroscopic findings. METHODS: Eighty six patients with longstanding shoulder joint pain were "blindly" examined by two trained doctors using several clinical tests. In all patients an ultrasonographic examination was performed, and in 42 (49%) an arthroscopy. RESULTS: Tests for impingement showed poor to moderate agreement. Tenderness of muscles, muscle weakness, and tests for labral lesion also showed poor agreement. Pain during muscle contraction showed moderate agreement. The agreement of clinical diagnoses was poor and the accuracy was low in comparison with arthroscopy. Ultrasonography was accurate in full thickness supraspinatus tendon tears, but inaccurate for partial tears and labral lesions. CONCLUSIONS: Most clinical tests showed poor agreement. Clinical and ultrasonographic diagnoses had low accuracy in comparison with arthroscopy.

Muscle reflexes during gait elicited by electrical stimulation of the posterior cruciate ligament in humans.

We investigated the influence of electrical stimulation of the posterior cruciate ligament (PCL) on the motoneuron pool of the thigh and calf muscle during gait. The study group comprised eight young men without any history of injury to the knee joints. Multistranded teflon-insulated stainless steel wires were inserted into the PCL guided by sonography and in four subjects also into the fat pad of the knee. The PCL was electrically stimulated during gait on a treadmill at heel strike and 100 ms after heel strike. Electromyographic signals were recorded with bipolar surface electrodes placed over the vastus medialis, rectus femoris, vastus lateralis, biceps femoris caput longum, and semitendinosus muscles. The stimuli consisted of four pulses delivered at 200 Hz; the stimulus amplitude was two to three times the sensory threshold. The electrical stimulation of the PCL inhibited the ongoing muscle activity in both the quadriceps and the hamstrings. The latency of the inhibition ranged between 78 and 148 ms in the quadriceps, between 88 and 110 ms in the hamstrings and between 189 and 258 ms in m. gastrocnemius. Stimulation of the fat pad of the knee did not influence the thigh and calf muscle motoneuron pool as evidenced by electromyography. The response elicited from the stimulation of the PCL was not limited to a specific muscle group but depended on ongoing muscle contraction, which suggests that the mechanoreceptors in the PCL are involved in the control of all muscles acting on the knee joint during gait.

[Diagnostic knee arthroscopy under local anesthesia in hospital. An assessment of the diagnostic reliability, course of the treatment and health care costs]. / Diagnostisk knaeartroskopi i lokalbedøvelse på sygehus. En vurdering af den diagnostiske sikkerhed, behandlingsforløbet og sundhedsvaesenets økonomi.

INTRODUCTION: Outpatient knee arthroscopy under local analgesia can be performed solely as a diagnostic procedure. The aim was to estimate the diagnostic precision of such arthroscopy as compared to the diagnosis made during a secondary therapeutic operation, and to describe the flow of patients and the costs of this treatment strategy. MATERIAL AND METHODS: The records of 371 consecutive patients, who had a diagnostic knee arthroscopy performed under local analgesia, were reviewed retrospectively. The diagnosis made during the diagnostic arthroscopy (371 patients) and a later therapeutic operation (135 patients) were extracted and the patients were asked to fill in a questionnaire. RESULTS: The diagnostic arthroscopy could not be completed in 11 cases. No further operation was necessary in 188 patients. A secondary therapeutic operation was performed in 135 patients. In only 54% of these was the same diagnosis made during the diagnostic and the therapeutic operations. Only half of the 278 patients (75%) who returned the questionnaire, found that the diagnostic procedure had been pain free. DISCUSSION: With respect to the costs, the diagnostic arthroscopy cannot be recommended. Most economic was the strategy in which the diagnostic and therapeutic operations were performed together as an outpatient procedure. The relatively poor diagnostic precision of arthroscopy is surprising and should be kept in mind when patients continue to have unexplained complaints in the knee, despite a normal arthroscopy.

Muscular reflexes elicited by electrical stimulation of the anterior cruciate ligament in humans.

Anterior cruciate ligament (ACL)-deficient knees have impaired proprioception, and, although mechanoreceptors have been found in the ACL, the existence of a reflex elicited from these receptors has not been directly demonstrated in humans. In eight patients that underwent knee arthroscopy and had no sign of ACL disease, thin wire electrodes were inserted into the proximal and mid parts of the ACL. Postoperatively, the sensory nerve fibers inside the ACL were stimulated electrically while motor activity in the knee muscles was recorded using electromyography. In seven of the eight patients, a muscular contraction of the semitendinosus muscle could be elicited with stimulus trains consisting of at least two stimuli. The latency was 95 +/- 35 ms. Stimulation during isometric contraction of either extensor or flexor muscles elicited a short, complete inhibition of the muscle activity in the contracting muscles. The latency of the inhibitory responses was 65 +/- 20 ms in the semitendinosus muscle and 70 +/- 15 ms in the rectus femoris muscle.

Sonographic guided insertion of electrodes into the cruciate ligaments of the knee.

The present cadaver study examined the probability of accurate ultrasound guided insertion of electrodes into the anterior (ACL) and posterior (PCL) cruciate ligament with a fine needle. Visualisation of the structures appeared clearest from the posterior approach. From this approach 24 electrodes were inserted into the PCL and six into the ACL. From the anterior 16 were inserted into the ACL and six into the PCL. Twenty-one out of 24 electrodes were placed correctly into the PCL from the posterior view, and four out of six were placed correctly from the anterior view. From the posterior view four out of six were placed correctly in the ACL, and eight electrodes out of 16 were placed correctly from the anterior view. In conclusion, ultrasound guided insertion of electrodes from the posterior view can be performed with high accuracy into the PCL, whereas insertion into the ACL seems to be less accurate, probably because it is more difficult to visualise.

Patient compliance and effect of orthopaedic shoes.

Orthopaedic shoes are individually handmade after a prescription from an orthopaedic surgeon, hence relatively expensive. Bad compliance is mentioned in the literature but not investigated. In order to evaluate patient compliance and the effect of orthopaedic shoes, 85 patients who were prescribed orthopaedic shoes at the authors' department during a 3 year period received a questionnaire concerning relief of symptoms and daily use of the shoes. The answers from 74 patients were correlated to the prescription procedure and the degree of medical follow-up. Only 60 of 74 patients used their shoes. Some 51 patients had some benefit while 23 had no effect or even worse symptoms. Some patients even used their shoes despite no symptomatic relief. However, patients who felt they were well informed about the purpose and function of their shoes had more benefit than the rest. Only 12 patients of the 74 were checked by the orthopaedic surgeon after delivery of the shoes. In conclusion the authors believe there is a great need for information to be given to the patients about the functions and limitations of orthopaedic shoes and that every patient should be offered a control check-up by the surgeon. Further investigations of the effect of orthopaedic shoes should be carried out to optimise the use of these expensive devices.