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Adhesive capsulitis of the shoulder (also known as frozen shoulder) is a painful and disabling disorder with an estimated prevalence ranging from 2% to 5% in the general population. Although the precise pathogenesis of frozen shoulder is unclear, thickened capsule and coracohumeral ligament (CHL) have been documented to be one of the most specific manifestations. The thickened CHL has been understood to limit external rotation of the shoulder, and restriction of internal rotation of the shoulder has been believed to be related to posterior capsular tightness. In this paper, three cases of refractory frozen shoulder treated through arthroscopic release of a contracted capsule including CHL were reported. Two cases in which there is recalcitrant severe restriction of internal rotation after manipulation under anesthesia (MUA) were finally treated with arthroscopic surgery. Although MUA could release the posterior capsule, internal rotation did not improve in our cases. After release of the thickened CHL, range of motion of internal rotation was significantly improved. This report demonstrates the role of the thickened CHL in limiting the internal rotation of the shoulder. We highlight the importance of release of thickened CHL in addition to the pancapsular release, in case of severe limitation of internal rotation of shoulder.

N-methylacetamide (NMA) crystal forms one-dimensional hydrogen-bond chains, which are similar to those in an acetanilide (ACN) crystal for which an unconventional vibrational band accompanying the amide-I band has been observed. Infrared spectra of NMA crystals show an additional band on the small-wave-number side of the amide-II band as the temperature is lowered. There is a close resemblance between this band and the band of ACN. It is likely that these bands appear by the same mechanism. The polaron model, which has been employed to explain the band of ACN, was found to be applicable also to the case of NMA, although the main vibrational mode is amide I in ACN and amide II in NMA. Acetanilide (ACN) and N-methylacetamide (NMA) are amides, which have characteristic infrared bands called amide I -VI. ' ACN forms one-dimensional hydrogenbond chains in the crystal and shows an unconventional vibrational band at low temperatures on the smallwave-number side of amide I, which is mainly attributed to the C =0 stretching vibration. ' The above band has been discussed in terms of the soliton model, the polaron model, ' or the Fermi-coupling model. Among these, the polaron model is the most reasonable, although some open questions still remain. NMA crystal has a melting point of 28 C and undergoes a phase transition at approximately 10'C. ' The low-temperature phase consists of one-dimensional hydrogen-bond chains similar to those in ACN crystal. "Dellepiane et al. ' reported that NMA crystal shows an unconventional infrared band around 1525 cm '. They interpreted this band in terms of the Fermi resonance between amide II, a band attributed mainly to the in-plane bending vibration of~N -H, and an overtone of amide V. However, we found that the overtone of amide V exists independently with a wave number almost twice that of amide V. The intensity of the unconventional band increases on cooling without apparent change in the wave number. There is an isosbestic point between this band and amide II, indicating that these bands exchange the intensity as the temperature is changed. It was also found that the unconventional band has its overtone.These observations are very similar to those in the case of ACN. Therefore, we analyzed the intensity of the band of NMA in terms of the polaron model, and compared the results with those for ACN. It has been reported that an unconventional Raman band was observed for NMA near amide I at a low temperature. ' However, we could not ascertain the existence of this band, nor could we observe a corresponding band in infrared spectra. Thus, we conclude that there is no unconventional band accompanying amide I of NMA crystal. N-methylacetamide (from the Tokyo Kasei Kogyo Co.) was purified three times by distillation under reduced pressure and once by sublimation at a low temperature. Since NMA is hygroscopic and oxidized in air, all the operations were made in a nitrogen-gas atmosphere. Samples of NMA for the infrared measurements were prepared by compressing the crystalline powder with KBr ...