Morphological characteristics of the infrapatellar fat pad.

The relationship between the morphological characteristics of the infrapatellar fat pad (IFP) and joint deformity has yet to be fully elucidated. Therefore, the purpose of this study was to clarify the morphological characteristics of the IFP and to identify the relationships between morphological characteristics of the IFP and degenerative grade of the articular surface of the patella. This investigation examined 41 legs from 25 Japanese cadavers. The IFP length, width, and volume were measured. It was categorized into three types: Type I, IFP proximal located on medial and lateral sides of the patella; Type II, the IFP proximal only located medially; and Type III, absence of the IFP proximal. Articular surfaces were graded as macroscopically intact or mildly altered (Grade I), moderately (Grade II), or severely (Grade III). Grade III was significantly more frequent than Grades I or II in Type III. IFP volume was significantly larger in Type I than in Types II or III. A negative correlation was found between the degenerative grade of the articular surface of the patella and IFP volume. It was suggested that a relationship between the degenerative grade of the articular surface of the patella and the IFP volume.

Contributions of the Third and Fourth Digits and the Second and Fifth Digits of the Flexor Digitorum Superficialis Muscle to Elbow Valgus Stability.

BACKGROUND: Thiel cadavers have been reported to have lifelike flexibility and mechanical properties, but whether they are useful for measurement of the ulnohumeral joint space (JS) is unclear. The contributions of the third and fourth digits and the second and fifth digits of the flexor digitorum superficialis (FDS) to elbow valgus stability are also unknown. PURPOSE: To (1) clarify whether Thiel cadavers can be used for JS measurement on ultrasound and (2) identify the contributions to valgus stability of the third and fourth digits and the second and fifth digits of the FDS. STUDY DESIGN: Descriptive laboratory study. METHODS: In experiment 1 (12 elbows from human volunteers and 12 elbows from Thiel cadavers), valgus stress was increased gradually from 0 to 30 to 60 N, and the JS was compared on ultrasound between groups at each load. In experiment 2 (13 elbows from Thiel cadavers), specimens were divided into 2 groups, and the JS was measured for group 1 with the FDS intact, with tendinous insertions of the third and fourth digits cut (3/4-cut state), and with tendinous insertions of all fingers cut (all-cut state); and for group 2 at intact FDS, with tendinous insertions of the second and fifth digits cut (2/5-cut state), and at all-cut. RESULTS: In experiment 1, the rate of change of the JS increased significantly with elbow valgus stress in both humans and Thiel cadavers, with no significant difference between groups. In experiment 2, the JS was significantly greater in the 3/4- and 2/5-cut states compared with the intact state at both 30 N (Δ3/4-cut vs intact = 0.23 mm [P = .01]; Δ2/5-cut vs intact = 0.32 mm [P = .02]) and 60 N (Δ3/4-cut vs intact = 0.33 mm [P = .002]; Δ2/5-cut vs intact = 0.37 mm [P = .04]). There was no significant difference in JS measurements between the 3/4- and 2/5-cut states at any load. CONCLUSION: Thiel cadavers showed JS changes similar to those of humans when valgus stress was applied. The third and fourth digits and the second and fifth digits of the FDS were involved in valgus stability, and there was no difference in their respective contributions. CLINICAL RELEVANCE: This study may help in identifying function of the FDS based on structure.

Relationship between morphology of transverse bundle of ulnar collateral ligament and adjacent tissues.

PURPOSE: The purpose of this study was to clarify the incidence of the transverse bundle (TB) of the ulnar collateral ligament (UCL), the relationships between TB morphology and morphology of the anterior bundle (AB) or posterior bundle (PB) of the UCL, and the relationship between the TB and the posterior common tendon (PCT). METHODS: This study examined 38 elbows from 23 cadavers. TB, AB, and PB were classified morphologically. The TB was classified as: type I, TB does not continue the entire length of the AB; or type II, TB continues the entire length of the AB. The AB and PB were classified as: type I, could be separated as single bundles; or type II, could not be separated. We also observed specimens by focusing on the continuity between the TB and PCT. Fisher's exact test was used to examine the relationship between TB type and AB or PB type. RESULTS: A TB was identified in all 38 elbows (100%), and continued to the AB in all specimens. No significant relationship was evident between TB type and AB or PB type. Continuity of TB fibers and the PCT was seen in 26 elbows (72%). CONCLUSION: This study suggested that the morphology of the transverse bundle may be unrelated to the morphology of the anterior bundle or posterior bundle.

Morphological features of the lateral plantar ligament of the transverse metatarsal arch.

The aim of this study was to elucidate the morphological characteristics of the lateral Lisfranc ligament in a large sample. This investigation examined 100 legs from 50 cadavers. Each of the lower limbs was dissected to identify the plantar aspect of the transverse metatarsal arch, and morphological characteristics of the lateral plantar ligament were assessed, including the length, width, and thickness of the fiber bundles. The majority of plantar ligaments originated from the base of M5 and the plantar aspect of the lateral cuneiform (LC). The lateral plantar ligament could be classified into three types: Type I, a band-like fiber bundle originating from the base of M5 to the LC (41%); Type II, originating from the base of M5 and the plantar aspect of LC and mostly connected the blending the fiber bundles of the tibialis posterior (TP) and long plantar ligament (LPL) (21%); and Type III, with no ligaments originating from the base of M5 and plantar aspect of the LC (38%). The morphological characteristics of Type I lateral plantar ligament were as follows: length, 31.8 ± 3.7 mm; width, 2.3 ± 1.0 mm; and thickness, 0.2 ± 0.3 mm. The morphology of the lateral plantar ligament showed variation, originating from the base of M5 and the plantar aspect of LC most commonly, but this was not the case in 38% of limbs. The findings suggest that the lateral plantar ligament might play a role in the transverse tarsal arch, indicating a cooperative mechanism with the TP and LPL.

Anatomical variations in the insertion of the peroneus longus tendon.

BACKGROUND: This study aimed to inspect anatomical variations in the insertion of the peroneus longus tendon (PLT) using a large sample of cadavers. METHODS: In total, 104 legs from 52 Japanese cadavers were used. The PLT was identified behind the lateral malleolus and carefully followed up to its insertion in the foot. All insertion slips of the PLT were located and documented. RESULTS: Mainly, the PLT was inserted to the base of the first metatarsal (1MT) in all 104 ft. Attachment to the medial cuneiform was present in 20.2%, and the first dorsal interossei was present in 36.5%. The anterior frenular ligament was observed in 31.7%, and attachment to the flexor digiti minimi brevis and opponens digiti minimi was present in 31.7%. The posterior frenular ligament was observed in 5.8%. An additional band was observed in 3.9%, and the adductor hallucis consisting of a caput obliquum was present in 3.9%. No statistically significant differences in the PLT were observed between genders or laterality (right vs. left). CONCLUSIONS: These findings suggest that the main function of the PLT is resisting the varus force on the 1MT; however, as the PLT has various attachment sites, it may also be involved in the stabilizing action of the longitudinal and transverse arches. Therefore, these variations and functions appear to be associated with a difficult diagnosis at the first clinical evaluation.

10 Hz transcranial alternating current stimulation over posterior parietal cortex facilitates tactile temporal order judgment.

The temporal order judgment (TOJ) task has been widely used to investigate spatial attentional bias and the sensitivity of temporal discrimination during the processing of bilateral tactile information. Previous studies have shown that TOJ is impaired in patients who are suffering from chronic pain, stroke, and Parkinson's disease. In addition, studies have indicated that the posterior parietal cortex (PPC) is involved in the TOJ task. However, the neural basis of the TOJ task has not been fully elucidated. To investigate the causal relationship between cortical oscillation and certain behaviors, transcranial alternating current stimulation (tACS) has been used. tACS can entrain an oscillation in the cortex to the applying frequency. In previous studies, increased alpha-band (around 10 Hz) oscillation in the PPC is associated with attentional inhibition of the contralateral side. Therefore, we hypothesized that 10 Hz tACS over PPC would inhibit tactile processing in the contralateral side, leading to ipsilateral spatial attentional bias and impaired temporal discrimination. However, we found that 10 Hz tACS over either side of the PPC facilitated temporal discrimination, with 10 Hz tACS over the right PPC leading to a rightward shift of attentional bias. These findings indicated that 10 Hz tACS over the PPC has a facilitative effect in the processing of bilateral tactile information, and may be useful for modulating or treating spatial bias or temporal discrimination during the integration of bilateral stimulation, at least in the somatosensory domain.