Comparative analysis of inter- and intraligamentous distribution of sensory nerve endings in ankle ligaments: a cadaver study

Outcomes of the "Calcaneo-stop" procedure for treating symptomatic flexible flatfoot in children: A systematic review and meta-analysis of 2394 feet

BACKGROUND

This study evaluates the efficacy of the calcaneo-stop (C-Stop) procedure's effectiveness in treating symptomatic flexible flatfoot (FFF) in children.

METHODS

A systematic review and meta-analysis were conducted using PubMed, Embase, and Cochrane databases to identify studies until 2023 on the outcomes of the C-Stop procedure in children with FFF. The risk of bias was assessed using MINORS criteria.

RESULTS

Of 85 studies screened, 20 involving 2394 feet from 1415 patients (mean age 11.2 ± 1.3 years) were included. Post-procedure, significant improvements were noted in pain reduction (93.5%), heel alignment (95.21%), and radiological measures, including reductions in Kite (7.32º), Meary (11.65º), Costa-Bartani angles (17.11º), talar declination (12.63º) and increase in Calcaneal Pitch Angle (5.92º). AOFAS scores increased by 22.32 points on average, with 94.83% reporting high satisfaction. Complication rate was low (7.8%).

CONCLUSIONS

The C-Stop procedure is effective for treating FFF in children, offering significant clinical, radiological, and functional improvements with high patient satisfaction and a low complication rate.

LEVEL OF EVIDENCE

Level IV, Systematic review of Level-IV studies.

Differences in Cortical Activation During Dorsiflexion and Plantarflexion in Chronic Ankle Instability: A Task-fMRI Study

BACKGROUND

Chronic ankle instability is a common sports injury that often presents with increased plantarflexion and restricted dorsiflexion. The cumulative effect of peripheral injuries may induce neuroplasticity in the central nervous system. However, the relationship between dorsiflexion or plantarflexion and the central nervous system in patients with chronic ankle instability remains unknown.

QUESTIONS/PURPOSES

(1) Is there a difference in region and voxel (volume pixel) of cortical activation during plantarflexion and dorsiflexion between patients with chronic ankle instability and a control group with normal ankle function? (2) Is there a correlation between activation of sensorimotor-related brain regions and three clinical measurement scales of ankle function and disease severity in patients with chronic ankle instability?

METHODS

Between December 2020 and May 2022, we treated 400 patients who had chronic ankle instability. Ten percent (40 patients; mean ± standard deviation age 29 ± 7 years; 17 male patients) were randomly selected to participate in this study. We recruited 42 volunteers with normal ankle function (mean age 28 ± 5 years; 21 male participants) matched by age and education level. A total of 2.5% (1 of 40) of patients with bilateral chronic ankle instability and 30% (12 of 40) with left-sided chronic ankle injury did not meet our inclusion criteria and were excluded from the study. The control group underwent MRI with good image quality. Finally, 27 patients with chronic ankle instability (mean age 26 ± 5 years; 10 male patients) and 42 participants with normal ankle function were enrolled. Ankle function and disease severity were assessed using three clinical scales: the Cumberland Ankle Instability Tool, Karlsson-Peterson Ankle Function Score, and the American Orthopedic Foot and Ankle Society Score. A uniplanar and nonweightbearing ankle dorsiflexion-plantarflexion paradigm (a recognized model or pattern) was performed using a short-block design during the functional MRI scan. This experimental design included a series of on-off periods consisting of movement and a rest period. From 15° of plantarflexion to 15° of dorsiflexion, the manipulator allowed 30° of ankle rotation. The cerebral excitability patterns between patients with chronic ankle instability and controls were analyzed using t-tests. We retained voxels with p values less than 0.05 in a voxel-level family-wise error correction. Clusters with voxel numbers greater than 10 were retained. The Cohen d coefficient was used to calculate between-group effect sizes. Spearman analysis was performed to explore the correlation between activation regions and the three clinical assessment scales.

RESULTS

In the patient group, cortical activation was greater during plantarflexion than during dorsiflexion, which was different from that in the control group. The between-group comparison showed that patients with chronic ankle instability had reduced activation in the ipsilateral precuneus (cluster size = 35 voxels [95% CI -0.23 to 0.07]; p < 0.001) during dorsiflexion, whereas during plantarflexion, chronic ankle instability caused increased activation in the ipsilateral superior temporal gyrus (cluster size = 90 voxels [95% CI -0.73 to -0.13]; p < 0.001), precuneus (cluster size = 18 voxels [95% CI -0.56 to -0.19]; p < 0.001), supplementary motor area (cluster size = 57 voxels [95% CI -0.31 to 0.00]; p < 0.001), superior frontal gyrus (cluster size = 43 voxels [95% CI -0.82 to -0.29]; p < 0.001), medial part of the superior frontal gyrus (cluster size = 39 voxels [95% CI 0.41 to 0.78]; p < 0.001), and contralateral postcentral gyrus (cluster size = 100 voxels [95% CI -0.32 to 0.02]; p < 0.001). Patients with chronic ankle instability showed a large effect size compared with controls (Cohen d > 0.8). During plantarflexion, the number of activated voxels in the supplementary motor area had a modest, positive correlation with the Karlsson-Peterson Ankle Function Score (r = 0.52; p = 0.01), and the number of activated voxels in the primary motor cortex (M1) and primary sensory cortex (S1) had a weak, positive correlation with the American Orthopedic Foot and Ankle Society Score in patients with chronic ankle instability (M1: r = 0.45; p = 0.02, S1: r = 0.49; p = 0.01).

CONCLUSION

Compared with volunteers with normal ankle function, patients with chronic ankle instability had increased cortical activation during plantarflexion and decreased cortical activation during dorsiflexion. We analyzed the central neural mechanisms of chronic ankle instability in patients with sports injuries and provided a theoretical basis for the development of new central and peripheral interventions in the future.

CLINICAL RELEVANCE

Because there was a positive correlation between the neural activity in sensorimotor-related regions during plantarflexion and clinical severity, clinicians might one day be able to help patients who have chronic ankle instability with neuromuscular rehabilitation by applying electrical stimulation to specific targets (such as S1M1 and the supplementary motor area) or by increasing activation of sensorimotor neurons through ankle movement.

Comparison of Clinical Outcomes With Arthroscopic ATFL Repair With the CFL Repair and Open ATFL and CFL Repair in Chronic Lateral Ankle Instability

It is important to eliminate instability related to chronic lateral ankle instability (CLAI) to prevent osteoarthritis progression. We performed arthroscopic anterior talofibular ligament (ATFL) repair and performed calcaneofibular ligament (CFL) repair if instability remained. This study aimed to assess the clinical outcomes of our arthroscopic procedure compared to that of open surgery. Forty ankles underwent arthroscopic surgery and 23 ankles underwent open surgery to repair the lateral ankle ligaments for CLAI. In the arthroscopic surgery, varus stress was applied under fluoroscopy after ATFL repair, and CFL repair was performed if instability remained. Open surgery was performed using the Broström procedure with ATFL and CFL repair. To assess clinical outcomes, American Orthopaedic Foot & Ankle Society (AOFAS) and Karlsson-Peterson (KP) scores were collected preoperatively and at the final follow-up. The talar tilt angle (TTA) was measured preoperatively and 1 year postoperatively. The arthroscopic group showed significantly higher AOFAS and KP scores at the final follow-up compared to the open surgery group. There was no significant difference in TTA at 1 year between the groups. In open surgery, 2 patients required revision surgery. There were no major complications, but scar-related pain in 2 cases of open surgery was reported. Arthroscopic ATFL repair with the CFL repair gave satisfactory clinical outcomes compared to open surgery in CLAI because of low invasive to soft tissue including the joint capsule. It is important to minimize soft tissue dissection in repairing the lateral ankle ligament in patients with CLAI.

Microstructural analysis on the innervation of the anterior, medial, and lateral human hip capsule: Preliminary evidence on its neuromechanical contribution

OBJECTIVE

Capsular repair aims to minimize damage to the hip joint capsular complex (HJCC) and subsequent dislocation risk following total hip arthroplasty (THA). Numerous explanations for its success have been advocated, including neuromuscular feedback loops originating from within the intact HJCC. This research investigates the hypothesis that the HJCC contributes to hip joint stability by analyzing HJCC innervation.

METHOD

Twenty-nine samples from the anterior, medial, and lateral aspects of the midportion HJCC of 29 individuals were investigated stereologically and immunohistochemically to identify encapsulated mechanoreceptors according to a modified Freeman and Wyke classification, totaling 11,745 sections. Consecutive slices were observed to determine the nerve course within the HJCC.

RESULTS

Few encapsulated mechanoreceptors were found in the HJCC subregions and overlying tissues across the cohort studied. Of regions studied, no significant regional differences in the density of mechanoreceptors were found. No significant difference in mechanoreceptor density was found between sides (left, 10.2×10-4/mm3, 4.0×10-4 - 19.0×10-4/mm3; right 12.9×10-4/mm3, 5.0×10-4 - 22.0×10-4/mm3; mean, 95% confidence intervals) sexes (female 10.4×10-4/mm3, 4.0×10-4 - 18.0×10-4/mm3; male 11.6×10-4/mm3, 5.0×10-4 - 20.0×10-4/mm3; mean, 95% confidence intervals), nor in correlation with age demographics. Myelinated nerves coursed consistently within the HJCC in various orientations.

CONCLUSION

Sparse mechanoreceptor density suggests that the HJCC contributes to a limited extent to hip joint stabilization. HJCC nerve terminals may potentially contribute to neuromuscular feedback loops with associated muscles to mediate joint stability in tandem with the active and passive components of the joint.

The morphology of the subacromial and related shoulder bursae. An anatomical and histological study

Shoulder bursae are essential for normal movement and are also implicated in the pathogenesis of shoulder pain and dysfunction. The subacromial bursa (SAB), within the subacromial space, is considered a primary source of shoulder pain. Several other bursae related to the subcoracoid space, including the coracobrachial (CBB), subcoracoid (SCB) and subtendinous bursa of subscapularis (SSB), are also clinically relevant. The detailed morphology and histological characteristics of these bursae are not well described. Sixteen embalmed cadaveric shoulders from eight individuals (five females, three males; mean age 78.6 ± 7.9 years) were investigated using macro-dissection and histological techniques to describe the locations, dimensions and attachments of the bursae, their relationship to surrounding structures and neurovascular supply. Bursal sections were stained with haematoxylin and eosin to examine the synovium and with antibodies against von Willebrand factor and neurofilament to identify blood vessels and neural structures respectively. Four separate bursae were related to the subacromial and subcoracoid spaces. The SAB was large, with a confluent subdeltoid portion in all except one specimen, which displayed a distinct subdeltoid bursa. The SAB roof attached to the lateral edge and deep surface of the acromion and coracoacromial ligament, and the subdeltoid fascia; its floor fused with the supraspinatus tendon and greater tubercle. The CBB (15/16 specimens) was deep to the conjoint tendon of coracobrachialis and short head of biceps brachii and the tip of the coracoid process, while the inconstant SCB (5/16 specimens) was deep to the coracoid process. Located deep to the subscapularis tendon, the SSB was a constant entity that commonly displayed a superior extension. Synovial tissue was predominantly areolar (SAB and SSB) or fibrous (CBB and SCB), with a higher proportion of areolar synovium in the bursal roofs compared to their floors. Blood vessels were consistently present in the subintima with a median density of 3% of the tissue surface area, being greatest in the SSB and SAB roofs (4.9% and 3.4% respectively) and least in the SAB floor (1.8%) and CBB roof and floor (both 1.6%). Nerve bundles and free nerve endings were identified in the subintima in approximately one-third of the samples, while encapsulated nerve endings were present in deeper tissue layers. The extensive expanse and attachments of the SAB support adoption of the term subacromial-subdeltoid bursa. Morphologically, the strong attachments of the bursal roofs and floors along with their free edges manifest as fixed and mobile portions, which enable movement in relation to surrounding structures. The presence of neurovascular structures demonstrates that these bursae potentially contribute blood supply to surrounding structures and are involved in mechanoreception. The anatomical details presented in this study clarify the morphology of the shoulder bursae, including histological findings that offer further insight into their potential function.

Clinical outcomes of anterior tibiofibular ligament's distal fascicle transfer versus ligament reconstruction with InternalBrace™ for chronic ankle instability patients

PURPOSE

Treatment of chronic ankle instability (CAI) for ankle sprain patients remains a challenge. If initial treatments fail, surgical stabilization techniques including ligament reconstruction should be performed. Anterior tibiofibular ligament (ATiFL) distal fascicle transfer for CAI was recently introduced. The goal of the study is to assess the 1-year clinical effectiveness of ATiFL's distal fascicle transfer versus ligament reconstruction with InternalBrace™ (Fa. Arthrex, Naples).

METHODS

Between October 2019 and February 2021, 25 patients (14 males and 11 females) scheduled for ligament reconstruction treatment of CAI were enrolled after propensity score matching. Twelve underwent ligament reconstruction with InternalBrace™ (InternalBrace™ group) and thirteen underwent ATiFL's distal fascicle transfer (ATiFL's distal fascicle transfer group). We recorded the American Orthopedic Foot & Ankle Society (AOFAS) score, Visual Analogue Scale (VAS), anterior drawer test grade, patient satisfaction and complications. All results of this study were retrospectively analyzed.

RESULTS

Statistically significant (p = 0.0251, independent-samples t test) differences in the AOFAS can be found between the ATiFL's distal fascicle transfer group and the InternalBrace™ group. No substantial changes in the VAS (p = 0.1778, independent-samples t test), patient satisfaction (p = 0.1800, independent-samples t test) and anterior drawer test grade (p = 0.9600, independent-samples t test) were found between the two groups. There was one patient with superficial wound infection and one patient with sural nerve injury in the InternalBrace™ group and ATiFL's distal fascicle transfer group, respectively.

CONCLUSION

This is the first study that assessed a cohort of CAI patients and suggests that the ATiFL's distal fascicle transfer operation has the potential to attain good-to-excellent clinical outcomes after 1-year recovery. The AOFAS scores were significantly higher for patients with ATiFL's distal fascicle transfer, indicating that this technique may be considered a viable option for both patients and their surgeon, while long-term outcomes should be investigated in the future.

Subtalar Arthroereisis for Surgical Treatment of Flexible Flatfoot

Various surgical techniques are known for the treatment of flexible flatfoot in children after failure of nonsurgical attempts. Data collected in a review of the last 10-year period (2010-2020) show that among the 691 feet undergoing subtalar arthroereisis with endorthesis, average age at surgery was 11.40 years and in the 1856 feet that underwent subtalar arthroereisis with calcaneo-stop 11.69 years, while the complications rate was 9.00% and 6.38%, respectively. These data confirm that subtalar arthroereisis with calcaneo-stop may have an advantage over subtalar arthroereisis with endorthesis as the screw is not placed across the subtalar joint but instead into the calcaneus.

Subtalar Arthroereisis for Flexible Flatfoot in Children-Clinical, Radiographic and Pedobarographic Outcome Comparing Three Different Methods

Subtalar arthroereises (STA) is a minimally invasive and reversible surgery to correct symptomatic flexible flatfoot (FFF) in children. Various techniques were described either applying expandable sinus tarsi implants or lateral calcaneus stop screws. Studies comparing the outcome of STA with different devices are rare. This retrospective single-center cohort study analyzes the results of STA using three different implants. 113 STA were performed in 73 consecutive patients (28 females). Mean age at surgery was 10.8 years (range 5-16). Mean follow-up was 29.0 months (range 1-111). In 21 feet the non-absorbable Kalix^® endorthesis and in 56 feet the absorbable Giannini endorthesis were applied. Subtalar extraarticular screw arthroereises (SESA) was conducted in 36 feet. Clinical, radiographic and pedobarographic parameters were analyzed. No intraoperative complications were observed. All three procedures achieved comparable improvements of the clinical, radiographic and pedobarographic parameters. The mean foot function index (FFI) improved from 36.4 (range 12-63) to 22.8 (range 2-55). The mean preoperative calcaneal inclination angle and the lateral talocalcaneal angle improved from 9.5° (range 0-22) and 42.3° (range 21-62) to 12.8° (range 0-26) and 37.6° (range 15-56), respectively. Pedobarographically determined values of the arch index, the medial midfoot contact area and the medial forefoot peak pressure decreased. In contrast to SESA (1/36, 3%), a higher incidence of implant-related complications was observed using Kalix^® (6/21, 29%) and Giannini (10/56, 8%) sinus tarsi implants. Peroneal muscle contractures only occurred in the SESA group (4/36, 11%). Premature removal due to treatment-related complications was necessary in 6/21 Kalix^® implants (29%), 4/56 Giannini implants (7%) and 4/36 SESA implants (11%). Implant choice for treatment of painful FFF in children with STA seems to play a subordinate role. Clinical, radiographic and pedobarographic outcomes are comparable between the applied implants. Surgeons and patients should be aware of the different spectrum of implant-related complications. Treatment can be reliably monitored by radiation-free pedobarography providing dynamic information about the deformity.

Immunohistochemical analysis of sensory corpuscles in human transplants of the anterior cruciate ligament

Background

Sensory nerve endings in ligaments play an important role for the proprioceptive function. Clinical trials show that the sense of body position does not fully recover in the knee joint after reconstructive surgery of the ruptured anterior cruciate ligament. The aim of this study is to identify sensory corpuscles in autogenous and allogenous transplants of the ligament and to compare their quantity between the used allografts and autografts.

Methods

Thirty-three patients were included in this study. Three patellar tendon allografts, 14 patellar tendon autografts and 12 semitendinosus autografts were harvested during revision surgery after traumatic rerupture of the graft. The control consisted of 4 healthy anterior cruciate ligaments after fresh rupture. After haematoxylin staining, immunohistochemical analysis was performed using antibodies against S100, p75 and PGP9.5. Microscopical examination was carried out, and the number of mechanoreceptors was counted. Statistical analysis was performed using the Mann-Whitney U test.

Results

Two types of mechanoreceptors were identified in each graft: Ruffini corpuscles and free nerve endings. The number of Ruffini corpuscles per square centimeter was the highest in the control. Comparing the grafts, the highest number of receptors could be detected in the semitendinosus autograft. The amount of free nerve endings was higher in the semitendinosus and patellar tendon autografts than in the control; the allografts showed the lowest number of receptors. With increasing time after reconstruction, the number of both types of receptors showed a decrease in the semitendinosus graft, whereas it increased in the patellar tendon graft and allograft. The number of mechanoreceptors in the semitendinosus and patellar tendon graft decreased over time after graft-failure, whereas it increased slightly in the allograft.

Conclusion

This study was the first to identify mechanoreceptors in human transplants of the anterior cruciate ligament. The partial increase in the number of receptors over time after reconstruction could indicate a reinnervation of the grafts.

Tarsometatarsal bone remodelling after subtalar arthroereisis

PURPOSE

Subtalar arthroereisis has been described for the treatment of flexible juvenile flatfoot. However, the mechanism responsible for deformity correction has not yet been investigated adequately. The aim of this study was to document the effect of subtalar arthroereisis on the tarsometatarsal bone morphology.

METHODS

We retrospectively reviewed the clinical and radiological data of 26 patients (45 feet) with juvenile flexible flatfoot deformity treated by subtalar arthroereisis at our department between 2000 and 2018. Radiological evaluation included angular measurements of tarsometatarsal bone morphology as well as hindfoot and midfoot alignment. Mean radiographic follow-up was 19.4 months (sd 8.8; 12 to 41).

RESULTS

A significant change of angular measurements of tarsometatarsal bone morphology was found after subtalar arthroereisis (p < 0.001). While there was an increase of the distal medial cuneiform angle (DMCA) and the medial cuneo-first metatarsal angle on the anteroposterior view, a decrease of the naviculo-medial cuneiform angle and the medial cuneo-first metatarsal angle was seen on the lateral view. Furthermore, we found significant improvements of all hindfoot and midfoot alignment parameters except the lateral tibio-calcaneal angle and the calcaneal pitch angle (p < 0.001).

CONCLUSION

Our data support the theory of tarsometatarsal bone remodelling, which may contribute to the effect of subtalar arthroereisis for the treatment of flexible juvenile flatfoot.

LEVEL OF EVIDENCE

IV.

Innervation of the hip joint capsular complex: A systematic review of histological and immunohistochemical studies and their clinical implications for contemporary treatment strategies in total hip arthroplasty

The hip joint capsule contributes to the stability of the hip joint and lower extremity, yet this structure is incised and often removed during total hip arthroplasty (THA). Increasing incidence of osteoarthritis is accompanied by a dramatic rise in THAs over the last few decades. Consequently, to improve this treatment, THA with capsular repair has evolved. This partial restoration of physiological hip stability has resulted in a substantial reduction in post-operative dislocation rates compared to conventional THA without capsular repair. A further reason for the success of this procedure is thought to be the preservation of the innervation of the capsule. A systematic review of studies investigating the innervation of the hip joint capsular complex and pseudocapsule with histological techniques was performed, as this is not well established. The literature was sought from databases Amed, Embase and Medline via OVID, PubMed, ScienceDirect, Scopus and Web of Science; excluding articles without a histological component and those involving animals. A total of 21 articles on the topic were identified. The literature indicates two primary outcomes and potential clinical implications of the innervation of the capsule. Firstly, a role in the mechanics of the hip joint, as mechanoreceptors may be present in the capsule. However, the nomenclature used to describe the distribution of the innervation is inconsistent. Furthermore, the current literature is unable to reliably confirm the proprioceptive role of the capsule, as no immunohistochemical study to date has reported type I-III mechanoreceptors in the capsule. Secondly, the capsule may play a role in pain perception, as the density of innervation appears to be altered in painful individuals. Also, increasing age may indicate requirements for different strategies to surgically manage the hip capsule. However, this requires further study, as well as the role of innervation according to sex, specific pathology and other morphometric variables. Increased understanding may highlight the requirement for capsular repair following THA, how this technique may be developed and the contribution of the capsule to joint function and stability.

Arthroscopic all-inside ATiFL's distal fascicle transfer for ATFL's superior fascicle reconstruction or biological augmentation of lateral ligament repair

PURPOSE

Tendon grafts are often utilized for reconstruction of the lateral ligaments unamenable to primary repair. However, tendon and ligaments have different biological roles. The anterior tibiofibular ligament's (ATiFL) distal fascicle may be resected without compromising the stability of the ankle joint. The aim of this study is to describe an all-arthroscopic and intra-articular surgical technique of ATiFL's distal fascicle transfer for the treatment of chronic ankle instability.

METHODS

Five unpaired cadaver ankles underwent arthroscopic ATiFL's distal fascicle transfer using a non-absorbable suture and a knotless anchor. Injured or absent ATiFL's distal fascicle were excluded from the study. Following arthroscopy, the ankles were dissected and evaluated for entrapment of nearby adjacent anatomical structures. The ligament transfer was also assessed. The distance between the anterolateral (AL) portals and the superficial peroneal nerve (SPN) was measured and the shortest distance was reported.

RESULTS

All specimens revealed successful transfer of the tibial origin of the ATiFL's distal fascicle onto the talar insertion of anterior talofibular ligament's (ATFL) superior fascicle. The fibular origin of the ATiFL's distal fascicle remained intact. There were no specimens with SPN or extensor tendon entrapment. The median distance between the proximal AL portal and SPN was 3.8 mm. The median distance between the distal AL portal and SPN was 3.9 mm.

CONCLUSION

An all-arthroscopic approach to an ATiFL's distal fascicle transfer is a reliable method to reconstruct the ATFL's superior fascicle. Transfer of ATiFL's distal fascicle avoids the need for tendon harvest or allograft. The lack of injury to nearby adjacent structures suggests that it is a safe procedure. The clinical relevance of the study is that ATiFL's distal fascicle can be arthroscopically transferred to be used as a biological reinforcement of the ATFL repair, or as an ATFL reconstruction.

The crural interosseous membrane re-visited: a histological and microscopic study

The aim of this study was to characterize the microscopic structure and sensory nerve endings of the crural interosseous membrane (IM). 13 IMs from 7 cadavers were used to analyze the organization of the collagen fibers, IM’s thickness, distribution of elastic fibers and nerve elements. The IM is mainly a two-layer collagen fascicle structure with the collagen fibers of adjacent layers orientated along different directions, forming angles of 30.5 +/- 1.7° at proximal and 26.6 +/- 2.1° at distal part (P>0.05). The percentage of elastic fibers between the two layers and inside the collagen fascicle layer is 10.1 +/- 0.5% and 2.2 +/- 0.1% (P<0.001). The IM’s thickness at proximal, middle, and distal parts is 268.5 +/- 18.6μm; 293.2 +/- 12.5μm; 365.3 +/- 19.3 μm, respectively (Proximal vs Distal: P<0.001; Middle vs Distal: P<0.05). Nerve elements were present and located both inside and on the surface of the IM, whereas the mechanoreceptors are mainly located on the surface of the IM. Free nerve endings (33.3 +/- 5.0/cm²) and Ruffini corpuscles (3.4 +/- 0.6/cm²) were the predominant sensory elements, while Pacinian corpuscles (1.3 +/- 0.7/cm²) were rarely found. The type of mechanoreceptors found suggests that the IM may play a role in proprioception.

Scapholunate interosseous ligament dysfunction as a source of elbow pain syndromes: Possible mechanisms and implications for hand surgeons and therapists

Elbow pain syndromes are common upper extremity musculoskeletal disorders, and they are usually associated with repetitive occupational exposure. Ligaments are often one of the sources of musculoskeletal disorders because of their mechanical and neurological properties. The wrist ligaments are some of the ligaments most vulnerable to occupational exposure. Since most occupational tasks require wrist extension for handling tools and loading, the scapholunate interosseous ligament (SLIL) bears greater strain during loading, which results in creep deformation and hysteresis. Ligamentous creep may result in diminished ability to detect signal changes during joint movements, which impairs neuromuscular control established by ligamentomuscular reflex arcs elicited from mechanoreceptors in the ligaments. Changes in muscle activation patterns of forearm muscles due to diminished ligamentomuscular reflexes may initiate a positive feedback loop, leading to musculoskeletal pain syndromes. The relationship between elbow pain syndromes and SLIL injury will be presented through two hypotheses and relevant pain mechanisms: 1. Repetitive tasks may cause creep deformation of the SLIL, which then impairs ligamentomuscular reflexes, leading to elbow pain disorders. 2. Lateral epicondylalgia may increase the risk of SLIL injury through the compensation of the lower extensor carpi radialis muscle activity by higher extensor carpi ulnaris muscle activity, which may alter carpal kinematics, leading to SLIL degeneration over time. The differential diagnosis is usually complicated in musculoskeletal pain disorders. The failure of treatment methods is one of the issues of concern for many researchers. A key element in developing treatment strategies is to understand the source of the disorder and the nature of the injury. We proposed that the differential diagnosis include SLIL injuries when describing elbow pain syndromes, particularly, lateral epicondylalgia.

The dimensions of the tarsal sinus and canal in different foot positions and its clinical implications

This study presents a reference for the dimensions of the tarsal sinus and canal in healthy adults in different foot positions to facilitate understanding of the kinematics of the subtalar joint, the effect of an implant, and other clinical issues. In a 3D CT stress test on 20 subjects, the right foot was forced into a neutral and eight different extreme foot positions while CT scans were obtained. The bones were segmented in the neutral foot position. The kinematics of the bones in the extreme positions were determined relative to the neutral position. The dimensions of the tarsal sinus and canal were calculated by determining the radii of the maximal inscribed spheres at 20 equidistant locations along an axis in 3D surface models of the tali and calcanei in each foot position. The radii were small on the medial side and increased laterally. Medial from the middle, the radii were small and not significantly different among the various foot positions. At the lateral side, the dimensions were affected mainly by eversion or inversion and less by dorsiflexion or plantarflexion. The pattern was reproducible among subjects, but there were between-subject differences. The dimensions are mostly determined by rotation in the frontal plane. A pivot point was found medial from the middle. These data serve as a reference and model for predicting the effect of sinus implants and understanding such clinical problems as sinus tarsi syndrome. Between-subjects differences have to be taken into account. Clin. Anat. 30:1049-1057, 2017. © 2017 Wiley Periodicals, Inc.

Can Bassett's ligament be removed?

PURPOSE

To investigate the functional characteristics of Bassett's ligament in the ankle, focusing on mechanoreceptors and potential problems following resection of Bassett's ligament.

METHODS

Bassett's ligament, the anterior talofibular ligament (ATFL), and synovium were obtained from 20 ankles of 10 fresh-frozen cadavers. Histologically, mechanoreceptors were identified and classified as Ruffini (type I), Vater-Pacini (type II), Golgi-Mazzoni (type III) corpuscles, and free nerve endings (type IV). Differences in receptor densities were compared.

RESULTS

Type I clusters were observed with three to six ramifications; type II mechanoreceptors were encapsulated in clusters of two to four with ovoid or cylindrical shape; type III were amorphous, long and wide, and fusiform- or spindle-shaped; and type IV were long and fine without a defined shape. Differences in the densities of the mechanoreceptors inside three soft tissues (Bassett's ligament, ATFL, and synovium) were not significant.

CONCLUSION

There were no significant differences in the densities of the four types of mechanoreceptors among the soft tissues studied. In Bassett's ligament, type I mechanoreceptors were present at significantly higher densities than the other receptors.

Altered Innervation Pattern in Ligaments of Patients with Basal Thumb Arthritis

Purpose The population of mechanoreceptors in patients with osteoarthritis (OA) lacks detailed characterization. In this study, we examined the distribution and type of mechanoreceptors of two principal ligaments in surgical subjects with OA of the first carpometacarpal joint (CMC1). Methods We harvested two ligaments from the CMC1 of eleven subjects undergoing complete trapeziectomy and suspension arthroplasty: the anterior oblique (AOL) and dorsal radial ligament (DRL). Ligaments were divided into proximal and distal portions, paraffin-sectioned, and analyzed using immunoflourescent triple staining microscopy. We performed statistical analyses using the Wilcoxon Rank Sum test and ANOVA with post-hoc Bonferroni and Tamhane adjustments. Results The most prevalent nerve endings in the AOL and DRL of subjects with OA were unclassifiable mechanoreceptors, which do not currently fit into a defined morphological scheme. These were found in 11/11 (100%) DRLs and 7/11 (63.6%) AOLs. No significant difference existed with respect to location within the ligament (proximal versus distal) of mechanoreceptors in OA subjects. Conclusion The distribution and type of mechanoreceptors in cadavers with no to mild OA differ from those in surgical patients with OA. Where Ruffini endings predominate in cadavers with no to mild OA, unclassifiable corpuscles predominate in surgical patients with OA. These findings suggest an alteration of the mechanoreceptor population and distribution that accompanies the development of OA. Clinical Relevance Identification of a unique type and distribution of mechanoreceptors in the CMC1 of symptomatic subjects provides preliminary evidence of altered proprioception in OA.

Immunohistochemical Mapping of Sensory Nerve Endings in the Human Triangular Fibrocartilage Complex

BACKGROUND

The triangular fibrocartilage complex is the main stabilizer of the distal radioulnar joint. While static joint stability is constituted by osseous and ligamentous integrity, the dynamic aspects of joint stability chiefly concern proprioceptive control of the compressive and directional muscular forces acting on the joint. Therefore, an investigation of the pattern and types of sensory nerve endings gives more insight in dynamic distal radioulnar joint stability.

QUESTIONS/PURPOSES

We aimed to (1) analyze the general distribution of sensory nerve endings and blood vessels; (2) examine interstructural distribution of sensory nerve endings and blood vessels; (3) compare the number and types of mechanoreceptors in each part; and (4) analyze intrastructural distribution of nerve endings at different tissue depth.

METHODS

The subsheath of the extensor carpi ulnaris tendon sheath, the ulnocarpal meniscoid, the articular disc, the dorsal and volar radioulnar ligaments, and the ulnolunate and ulnotriquetral ligaments were dissected from 11 human cadaver wrists. Sensory nerve endings were counted in five levels per specimen as total cell amount/cm(2) after staining with low-affinity neurotrophin receptor p75, protein gene product 9.5, and S-100 protein and thereafter classified according to Freeman and Wyke.

RESULTS

All types of sensory corpuscles were found in the various structures of the triangular fibrocartilage complex with the exception of the ulnolunate ligament, which contained only Golgi-like endings, free nerve endings, and unclassifiable corpuscles. The articular disc had only free nerve endings. Furthermore, free nerve endings were the predominant sensory nerve ending (median, 72.6/cm(2); range, 0-469.4/cm(2)) and more prevalent than all other types of mechanoreceptors: Ruffini (median, 0; range, 0-5.6/cm(2); difference of medians, 72.6; p < 0.001), Pacini (median, 0; range, 0-3.8/cm(2); difference of medians, 72.6; p < 0.001), Golgi-like (median, 0; range, 0-2.1/cm(2); difference of medians, 72.6; p < 0.001), and unclassifiable corpuscles (median, 0; range, 0-2.5/cm(2); difference of medians, 72.6; p < 0.001). The articular disc contained fewer free nerve endings (median, 1.8; range, 0-17.8/cm(2)) and fewer blood vessels (median, 29.8; range, 0-112.2/cm(2); difference of medians: 255.9) than all other structures of the triangular fibrocartilage complex (p ≤ 0.001, respectively) except the ulnolunate ligament. More blood vessels were seen in the volar radioulnar ligament (median, 363.62; range, 117.8-871.8/cm(2)) compared with the ulnolunate ligament (median, 107.7; range, 15.9-410.3/cm(2); difference of medians: 255.91; p = 0.002) and the dorsal radioulnar ligament (median, 116.2; range, 53.9-185.1/cm(2); difference of medians: 247.47; p = 0.001). Free nerve endings were obtained in each structure more often than all other types of sensory nerve endings (p < 0.001, respectively). The intrastructural analysis revealed no differences in mechanoreceptor distribution in all investigated specimens with the numbers available, showing a homogenous distribution of proprioceptive qualities in all seven parts of the triangular fibrocartilage complex.

CONCLUSIONS

Nociception has a primary proprioceptive role in the neuromuscular stability of the distal radioulnar joint. The articular disc and ulnolunate ligament rarely are innervated, which implies mainly mechanical functions, whereas all other structures have pronounced proprioceptive qualities, prerequisite for dynamic joint stability.

CLINICAL RELEVANCE

Lesions of the volar and dorsal radioulnar ligaments have immense consequences not only for mechanical but also for dynamic stability of the distal radioulnar joint, and surgical reconstruction in instances of radioulnar ligament injury is important.

Morphological study of mechanoreceptors in collateral ligaments of the ankle joint

BACKGROUND

The aim of this study was to analyze the pattern and types of sensory nerve endings in ankle collateral ligaments using histological techniques, in order to observe the morphology and distribution of mechanoreceptors in the collateral ligaments of cadaver ankle joint, and to provide the morphological evidence for the role of the ligament in joint sensory function.

METHODS

Twelve lateral collateral ligaments including anterior talofibular ligament (ATFL; n = 6), posterior talofibular ligament (PTFL; n = 6), and calcaneofibular ligament (CFL; n = 6) were harvested from six fresh frozen cadavers. The ligaments were embedded in paraffin, sectioned at 4 μm, and then stained using a modified gold-chloride staining methods. The collateral ligament was divided into three segments: proximal, middle, and distal segments. Fifty-four ATFL slides, 90 PTFL slides, and 108 CFL slides were analyzed. Mechanoreceptors were classified based on Freemen and Wyke's classification. Mechanoreceptor distribution was analyzed statistically. One-way ANOVA (postHoc LSD) was used for statistical analysis.

RESULTS

All the four typical types of nerve endings (the Ruffini corpuscles, Pacinian corpuscles, Golgi tendon organs, and free nerve endings) were identified in these ligaments. Pacinian corpuscles were the predominant in all four complexes. More mechanoreceptors were found in synovial membrane near both ends of the ligaments attached to the bone. No statistical differences were found in the amount of mechanoreceptors among distal, middle, and proximal parts of the ligaments.

CONCLUSIONS

The four typical types of mechanoreceptors were all identified in the collateral ligaments of the human ankle. Pacinian corpuscles were the predominant in all four complexes. This indicates that the main function of ankle collateral ligaments is to sense joint speeds in motions.

Mechanoreceptors in the Anterior Horn of the Equine Medial Meniscus: an Immunohistochemical Approach

Lameness due to stifle and especially meniscal lesions is frequent in equine species. In humans, mechanoreceptors involved in proprioceptive function are well studied. Given the high incidence of meniscal injuries in horses, and the lack of information concerning them in equine menisci, our objective was to study these corpuscles in six healthy anterior horns of the equine medial meniscus, which is the most common localisation reported for equine meniscal injuries. Immunohistochemical stainings were performed using antibodies against high molecular weight neurofilaments and glial fibrillary acidic proteins. From a purely fundamental point of view, our work highlights for the first time the presence of Ruffini, Pacini and Golgi corpuscles in equine meniscus. They were found, isolated or in clusters and always located at the vicinity of blood vessels, at the level of the anterior horn of the equine medial meniscus. This morphological approach could serve as a basis for clinical studies, to evaluate the impact of these corpuscles on the poor sportive prognosis in equine meniscal tears.

Histological analysis of the structural composition of ankle ligaments

BACKGROUND

Various ankle ligaments have different structural composition. The aim of this study was to analyze the morphological structure of ankle ligaments to further understand their function in ankle stability.

METHODS

One hundred forty ligaments from 10 fresh-frozen cadaver ankle joints were dissected: the calcaneofibular, anterior, and posterior talofibular ligaments; the inferior extensor retinaculum, the talocalcaneal oblique ligament, the canalis tarsi ligament; the deltoid ligament; and the anterior tibiofibular ligament. Hematoxylin-eosin and Elastica van Gieson stains were used for determination of tissue morphology.

RESULTS

Three different morphological compositions were identified: dense, mixed, and interlaced compositions. Densely packed ligaments, characterized by parallel bundles of collagen, were primarily seen in the lateral region, the canalis tarsi, and the anterior tibiofibular ligaments. Ligaments with mixed tight and loose parallel bundles of collagenous connective tissue were mainly found in the inferior extensor retinaculum and talocalcaneal oblique ligament. Densely packed and fiber-rich interlacing collagen was primarily seen in the areas of ligament insertion into bone of the deltoid ligament.

CONCLUSIONS

Ligaments of the lateral region, the canalis tarsi, and the anterior tibiofibular ligaments have tightly packed, parallel collagen bundles and thus can resist high tensile forces. The mixed tight and loose, parallel oriented collagenous connective tissue of the inferior extensor retinaculum and the talocalcaneal oblique ligament support the dynamic positioning of the foot on the ground. The interlacing collagen bundles seen at the insertion of the deltoid ligament suggest that these insertion areas are susceptible to tension in a multitude of directions.

CLINICAL RELEVANCE

The morphology and mechanical properties of ankle ligaments may provide an understanding of their response to the loads to which they are subjected.

Subtalar extra-articular screw arthroereisis (SESA) for the treatment of flexible flatfoot in children

PURPOSE

The aim of this study was to describe a subtalar extra-articular screw arthroereisis (SESA) technique for the correction of flexible flatfoot (FFF) in children and report the outcome.

METHODS

From 1990 to 2012, data were collected on 485 patients who underwent SESA at the San Raffaele Hospital. The average age of the patient cohort was 11.5 ± 1.81 years (range 5.0-17.9 years; median 11.5 years). Inclusion criteria were FFF and marked flexible hindfoot valgus, and the exclusion criterion was rigid flatfoot. SESA was performed in 732 cases of FFF-bilaterally in 247 patients and monolaterally in 238 patients.

RESULTS

The values of the pre- and post-SESA weight-bearing X-ray angles were 146° ± 7° and 129° ± 5°, respectively, for the Costa-Bartani angle, 43° ± 8° and 25° ± 6°, respectively, for the talar inclination angle and 11° ± 6° and 14° ± 5°, respectively, for calcaneal pitch (p <0.001). All data were analysed statistically with Student's t test. Data on 398 patients were ultimately available for analysis. In 93.7 % of cases the results were good in terms of improved clinical aspects and X-ray measurement, absence of complications, normal foot function 3 months post-SESA and no requirement for further surgery. The complication rate was 6.3 % and included ankle joint effusion, painful contracture of peroneal muscles and fourth metatarsal bone stress fractures. A sample of 76 patients (121 feet) were evaluated after screw removal, which occurred on average 2.9 years after SESA. The angle measurements of this sample showed no statistically significant modification.

CONCLUSION

Based on our >20 years of experience, we believe that SESA is an optimal technique for the correction of FFF as it is simple and can be performed rapidly, and the corrective effect results from the screw's mechanical and proprioceptive effect. The indication for surgery must be accurate. We suggest that the patient be at least 10 years of age in order that all of the foot's growth potential can be utilized and to allow for spontaneous resolution and thereby avoid the possibility of over-treatment.

[Lateral ligament injuries of the ankle joint]

Lateral ligament injuries are the most common sports injury and have a high incidence even in non-sportive activities. Although lateral ligament injuries are very common there is still a controversial debate on the best management. The diagnosis is based on clinical examination and X-ray images help to rule out fractures. Further imaging, especially magnetic resonance imaging (MRI) is used to diagnose associated injuries. According to the recommendations of the various scientific societies the primary therapy of lateral ligament injuries is conservative. Chronic ankle instability develops in 10-20 % of patients and the instability can be a result of sensomotoric deficits or insufficient healing of the lateral ligament complex. If the patient does not respond to an intensive rehabilitation program an operative reconstruction of the lateral ligaments has to be considered. Most of the procedures currently performed are anatomical reconstructions due to better long-term results compared to tenodesis procedures.

Distribution of sensory nerve endings around the human sinus tarsi: a cadaver study

The aim of this study was to analyse the pattern of sensory nerve endings and blood vessels around the sinus tarsi. The superficial and deep parts of the fat pads at the inferior extensor retinaculum (IER) as well as the subtalar joint capsule inside the sinus tarsi from 13 cadaver feet were dissected. The distribution of the sensory nerve endings and blood vessels were analysed in the resected specimens as the number per cm(2) after staining with haematoxylin-eosin, S100 protein, low-affinity neurotrophin receptor p75, and protein gene product 9.5 using the classification of Freeman and Wyke. Free nerve endings were the predominant sensory ending (P < 0.001). Ruffini and Golgi-like endings were rarely found and no Pacini corpuscles were seen. Significantly more free nerve endings (P < 0.001) and blood vessels (P = 0.01) were observed in the subtalar joint capsule than in the superficial part of the fat pad at the IER. The deep part of the fat pad at the IER had significantly more blood vessels than the superficial part of the fat pad at the IER (P = 0.012). Significantly more blood vessels than free nerve endings were seen in all three groups (P < 0.001). No significant differences in distribution were seen in terms of right or left side, except for free nerve endings in the superficial part of the fat pad at the IER (P = 0.003). A greater number of free nerve endings correlated with a greater number of blood vessels. The presence of sensory nerve endings between individual fat cells supports the hypothesis that the fat pad has a proprioceptive role monitoring changes and that it is a source of pain in sinus tarsi syndrome due to the abundance of free nerve endings.