Delayed primary reconstruction of subtotal nail bed loss using a split-thickness nail bed graft on decorticated bone

Split-thickness nail bed grafting is the accepted method of treatment for injuries involving loss of nail bed tissue. The nail bed of the great toe may be used without donor-site morbidity, and nail bed grafting may be combined with other procedures for fingertip reconstruction. A case of fingertip avulsion injury with loss of the nail plate, nail bed, and periosteum over the exposed distal phalanx of the thumb was reconstructed by a split-thickness nail bed graft placed directly on granulating decorticated bone. The length, appearance, and function of the injured dominant thumb were preserved.     

Congenital curved nail of the fourth toe

Five cases of congenital curved nail of the fourth toe are reported. Patients included four males and one female; four cases were bilateral, and one was unilateral. There were no other significant associated anomalies of the extremities, and only the fourth toes were affected. The features of the deformity are a curved nail and hypoplasia of the soft tissue and bone of the distal phalanx of the fourth toe. This anomaly may be transmitted autosomally and is unique in that it may be of mesodermic origin.     

甲下外生性骨疣的临床病理分析

目的阐述甲下外生性骨疣的临床、影像、病理特征。方法收集中国医科大学附属盛京医院2006年1月～2011年12月甲下外生性骨疣14例进行分析,并参阅文献。结果14例患者平均年龄13岁,11例位于拇趾,病程2个月～3年,临床上出现甲下或甲旁的结节、疼痛、感染、趾甲异常。x线多表现为趾骨远端的骨性突起,基底与趾骨相连,大小0．5～1．2厘米。组织学上,表现为基底的成熟骨组织表面被覆纤维软骨。有随访结果的6例中1例术后1年复发。结论甲下外生性骨疣有典型的临床、影像、病理特点。手术时应确认肿物和甲床的关系,做到既将肿物完全切除以防止复发,同时又保护甲床,对甲床进行精确的修复以尽量避免指甲变形或丧失。     

Custom-made free vascularized compound toe transfer for traumatic dorsal loss of the thumb

Dorsal compound traumatic thumb loss can be reconstructed in selected young and well-motivated patients with a custom-made partial great toe transfer. The transfer, including the nail complex and vascularized piece of bone, can be fashioned by longitudinally cutting the distal phalanx to approach the appearance of the opposite thumb and to allow for more normal nail appearance. Ten patients illustrate this technique and emphasize its reconstructive potential as well as cosmetic acceptance.     

A new species of dactyloid anole (Iguanidae, Polychrotinae, Anolis) from the southeastern slopes of the Andes of Ecuador

We describe a new species of Anolis from the southeastern slopes of the Andes of Ecuador, province of Zamora-Chinchipe, Parque Nacional Podocarpus. It belongs to (1) the aequatorialis species-group by being of moderate to large size with narrow toe lamellae, and (2) the eulaemus sub-group by having a typical Anolis digit, in which the distal lamellae of phalanx II distinctly overlap the proximal scales of phalanx I. The new species is most similar morphologically to Anolis fitchi but differs from it mainly by having a dewlap with longitudinal rows of 2-5 granular, minute scales separated by naked skin (longitudinal rows of one or two keeled, large scales separated by naked skin in Anolis fitchi) and a vertically shorter dewlap (longer dewlap in Anolis fitchi).     

Fingertip reconstructions using partial-toe transfers

Fifty-six partial toes were transferred to reconstruct fingertip deficits. The transfers from the big toe mainly consisted of 3 trimmed big toetips, 3 vascularized nail grafts, 3 onychocutaneous flaps, 19 thin osteo-onychocutaneous flaps, and 2 hemipulp flaps. The transfers from the second toe mainly consisted of 8 trimmed second toetips, 5 reduced second toes, and 9 whole distal phalanges. The average values of postoperative sensory recovery of the osteo-onychocutaneous flaps including the vascularized nail grafts were 3.1 (Semmes-Weinstein test) and 6.3 mm (moving two-point discrimination) at 2.6 years after the transfer; those of the thin osteo-onychocutaneous flaps were 3.1 and 7.2 mm at 2.0 years after surgery; those of the trimmed big toe tip transfers were 3.61 and 6.5 mm at 1.8 years after surgery; and those of the trimmed second toetip transfers were 3.37 and 6.3 mm at 2.6 years after transfer. Those of the distal phalanx of the second toe were 3.41 and 7.9 mm at 1.2 years after surgery, and those of the reduced second toe were 3.2 and 6.7 mm at 10.6 months after surgery.     

The boomerang flap in managing injuries of the dorsum of the distal phalanx

Finding an appropriate soft-tissue grafting material to close a wound located over the dorsum of a finger, especially the distal phalanx, can be a difficult task. The boomerang flap mobilized from the dorsum of the proximal phalanx of an adjacent digit can be useful when applied as an island pedicle skin flap. The vascular supply to the skin flap is derived from the retrograde perfusion of the dorsal digital artery. Mobilization and lengthening of the vascular pedicle are achieved by dividing the distal end of the dorsal metacarpal artery at the bifurcation and incorporating two adjacent dorsal digital arteries into one. The boomerang flap was used in seven individuals with injuries involving the dorsal aspect of the distal phalanx over the past year. Skin defects in all patients were combined with bone,joint, or tendon exposure. The authors found that the flap was reliable and technically simple to design and execute. This one-step procedure preserves the proper palmar digital artery to the fingertip and has proven valuable for the coverage of wide and distal defects because it has the advantages of an extended skin paddle and a lengthened vascular pedicle. When conventional local flaps are inadequate, the boomerang flap should be considered for its reliability and low associated morbidity.     

Pulp nonfiction: microscopic anatomy of the digital pulp space

The volar pad of the fingertip provides a very stable yet sensitive surface that gives the hand the ability to pinch and grasp. The focus of this study was to advance understanding of the anatomical features of the digital pulp space. The unusual features of the fingertip pulp space include prominent collagen fiber cords and a branching continuous fine vasculature. Prominent collagen fiber cords radiating out from beneath the epidermal basement membrane are like the cords of a parachute, which directly attach to the periosteum of the distal phalanx. Those collagen fiber cords are responsible for the firm attachment of the fingertip to the distal phalanx. There is a fine patent vasculature within the pulp space. Also contained in the capsule are numerous lobules of fat, which contribute to some elasticity of the fingertip. Principles of treatment for injuries or infections of the digital pulp should attempt to preserve this anatomical construct so that the firmness and vascular supply of the fingertip are maintained and not disrupted.     

Development and regeneration of the neonatal digit tip in mice

The digit tips of children and rodents are known to regenerate following amputation. The skeletal structure that regenerates is the distal region of the terminal phalangeal bone that is associated with the nail organ. The terminal phalanx forms late in gestation by endochondral ossification and continues to elongate until sexual maturity (8 weeks of age). Postnatal elongation at its distal end occurs by appositional ossification, i.e. direct ossification on the surface of the terminal phalanx, whereas proximal elongation results from an endochondral growth plate. Amputation through the middle of the terminal phalanx regenerates whereas regenerative failure is observed following amputation to remove the distal 2/3 of the bone. Regeneration is characterized by the formation of a blastema of proliferating cells that appear undifferentiated and express Bmp4. Using chondrogenic and osteogenic markers we show that redifferentiation does not occur by endochondral ossification but by the direct ossification of blastema cells that form the rudiment of the digit tip. Once formed the rudiment elongates by appositional ossification in parallel with unamputated control digits. Regenerated digits are consistently shorter than unamputated control digits. Finally, we present a case study of a child who suffered an amputation injury at a proximal level of the terminal phalanx, but failed to regenerate despite conservative treatment and the presence of the nail organ. These clinical and experimental findings expand on previously published observations and initiate a molecular assessment of a mammalian regeneration model.     

Sequence of ossification of the foot in marmosets (Saguinus oedipus)

The cleared and alizarin-stained feet of eight marmoset (Saguinus oedipus) fetuses revealed a sequence of initial ossification of the 19 bones of the foot that is almost totally different from that of man. The most striking difference is in the order of ossification of the distal phalanx of the big toe; in man it is the first bone to commence ossification, in the marmoset it is the fourteenth. It is suggested that the sequence of initial ossification in the foot may be species specific among the primates and may serve as a useful marker of teratogenic action.     

Treatment of lateral ray polydactyly of the foot: focusing on the selection of the toe to be excised

The purposes of this study were to evaluate the results of the operative treatment of lateral ray polydactyly and to consider appropriate surgical procedures, especially focusing on the selection of the toe, lateral toe or medial toe, to be resected. Twenty-two patients with lateral ray polydactyly foot (25 individual feet) at an average of 71 months' follow-up were included in this study. Cases were classified morphologically into three types on the basis of Hirase's configuration. In addition, these types were divided into two subtypes, metatarsal and phalangeal, on the basis of radiographic evaluation of the level of duplication. The clinical evaluations of the reconstructed toe were performed, and these results were investigated according to their morphologic classification and excised toe group. The distinctive problem of medial toe excision is valgus deformity. Eight of 25 toes retained persistent valgus deformity, and all of these cases were in the medial toe excision group. On the other hand, a distinctive problem in lateral toe excision is postoperative pain. Two patients suffered from postoperative pain in phalangeal type cases in the lateral toe excision group, and the remaining medial toe had a medial protuberant middle phalanx. The pain occurred at that protuberant point. Based on their experiences, the authors created an algorithm for selection of the toe to be excised. In metatarsal type cases, from a functional perspective, the toe that has a radiographically dominant metatarsus should be retained. On the other hand, in phalangeal type cases, the authors give priority to shape rather than function, and they excise the morphologically smaller toe independent of the condition of the phalanx as viewed on radiography. If the medial toe and the lateral toe are approximately the same size, the authors excise the lateral toe to avoid valgus deformity. When the lateral toe has severe valgus deformity that seems unlikely to be correctable intraoperatively, the lateral toe should be considered for excision even if it is larger than the medial toe.     

Microevolutionary changes in the skeleton of the foot of Japanese: Special reference to the medial longitudinal arch

This study concerns secular changes of the foot of Japanese, from the prehistoric Jomon period to early modern times. The size of the talus, calcaneus and first metatarsal changed in parallel with the estimated stature, during this period. In the case of the calcanues, length-height-index, length-tuberosity height-index, Böhler's tuber-joint angle and angle of cuboidal articular surface gradually increased with time. Thus, all may take part in elevation of the longitudinal arch. With time, the relative height of the subtalar, talonavicular, cuneonavicular and first tarsometatarsal joints in the reconstructed medial arch enlarged, in parallel with the increase in the inclination angles of both the calcaneus and the first metatarsal. In addition, valgus deviation of the distal phalanx of the great toe became conspicuous in comparatively recent times. These changes no doubt were accelerated by modification in life style.     

Collateral ligaments of the distal sesamoid bone in the digit of Equus: re-evaluating midstance function

The distal forelimb of the horse has a complex array of ligaments that play a critical role in determining function of the digit and are often associated with the initiation of foot pathologies. The collateral ligaments of the distal sesamoid bone (CLDS) play an important role in digit stabilization near the end of foot contact and there is also limited evidence to suggest that the CLDS stabilize the proximal interphalangeal joint (PIPJ) during weight bearing. By virtue of their anatomical attachments where the ligaments pass dorsal to the axis of rotation of the PIPJ, it is reasonable to assume that the CLDS prevent flexion of the PIPJ during weight bearing or midstance in a moving horse. To test this functional hypothesis, forelimb specimens from three mixed-breed horses were loaded in compression in a materials testing frame. Limb loading was applied with the CLDS intact and following transection. Average PIPJ angle and metacarpophalangeal joint (MCPJ) angle at maximum load (approximately 3000 N) were calculated from angular changes of proximal and middle phalanges and the third metacarpal, which were compared between intact and transected trials. PIPJ angles were found to be the same (175 degrees) at maximum load for intact and transected trials. The proximal and middle phalanges rotated together remaining aligned, regardless of the CLDS condition. Contrary to expectation, however, the combined proximal and middle phalanges unit rotates less relative to the third metacarpal under load after transection, indicating less digit extension at the metacarpophalangeal (fetlock) joint without the influence of CLDS. Since the mechanical properties of the fetlock joint are unchanged by CLDS transection, observed proximal and middle phalanx motion is dependent on increased rotation of the distal phalanx after transection. The original hypothesis was not supported and the results suggest that at midstance the CLDS function primarily to stabilize the articulation of the middle phalanx about the distal phalanx to limit distal interphalangeal joint extension during weight bearing. Establishing the functional role of the CLDS may help to better understand the biomechanical consequences of ligament injuries and diseases of the pastern.     

Pumiliornis tessellatus Mayr, 1999 revisited — new data on the osteology and possible phylogenetic affinities of an enigmatic Middle Eocene bird

Although the avian speciesPumiliornis tessellatus Mayr, 1999 is known from two skeletons from the Middle Eocene of Messel in Germany, its phylogenetic affinities remained enigmatic. The new osteological data presented in this study document thatP. tessellatus had an at least semizygodactyl foot, with a very wide basal phalanx of the fourth toe, and lacked an ossified pons supratendineus on the distal tibiotarsus. Compared to the known zygodactyl and semizygodactyl birds, this tiny Middle Eocene species resembles the late Eocene/early Oligocene taxonEocuculus Chandler, 1999. Anew, tentatively referred wing ofEocuculus from the early Oligocene of France is described and compared withPumiliornis.      

Claw retraction and protraction in the carnivora: Skeletal microvariation in the phalanges of the Felidae

All carnivorans retract and protract their claws. In felids and some viverrids the claws of digits II through V of both the manus and pes have a larger arc of rotation than those of other carnivorans; the claws retract to the lateral side of the middle phalanx rather than onto its dorsal surface as in most other carnivorans. This condition should be termed hyper-retraction. Morphological features of the middle and distal (ungual) phalanges that have been purported to be necessary for hyper-retraction in felids vary considerably among digits within the manus and pes. These features include the lateral projection of the distal head and the asymmetry of the shaft of the middle phalanx, and the oblique orientation of the articular surface on the distal phalanx. None of these features is necessary in every instance for hyperretraction, and some of the variation in these features is associated instead with protraction. Differences among digits in the orientation of the articular surface on the distal phalanx are associated with differences in the degree to which the claws must move laterally to rotate from the protracted to the retracted position. Differences in the orientation of the distal head on the middle phalanx are associated with the spreading of the claws during protraction. The manual claws are hook-shaped, whereas the pedal claws are more blade-like; this morphological difference is associated with differences in function between the manus and pes. In the manus the medial claws have a larger radius of curvature and a smaller angle of arc as compared to the more lateral claws; in the pes, the claws on digits III and IV have larger radii of curvature and smaller angles of arc. Digit I of the manus lacks the hyper-retraction mechanism; nonetheless, this digit shares many of the attributes that are associated with this mechanism. © 1996 Wiley-Liss, Inc.     

Mechanical advantages of the Neanderthal thumb in flexion: a test of an hypothesis

It has been proposed that the pollical phalangeal length proportions of the Neanderthals provided them with a greater mechanical advantage relative to recent humans for their pollical flexor muscles in power grips across the interphalangeal (IP) joint at the expense of the mechanical advantage of those pollical flexor muscles in precision grips at the finger tip. To test these related hypotheses, we compared the pollical load arm dimensions (phalanx lengths) to power arm dimensions (dorsopalmar articular heights) for the European and Near Eastern Neanderthals and for European and Amerindian samples of recent humans. It was found, initially, that the proximal articular height of the pollical distal phalanx is a poor predictor of the power arm at the IP articulation, even though the proximal articular height of the pollical proximal phalanx was an adequate indicator of the power arm size at the metacarpophalangeal (MCP) joint. In addition, differences in distal pollical ulnar deviation at the IP joint appeared to make little difference in the mechanical advantage comparisons. More importantly, the relative shortness of Neanderthal proximal pollical phalanges and the relative lengthening of their distal pollical phalanges was confirmed, and it was determined that, despite some minor differences in articular dimensions between Neanderthals and recent humans, these pollical phalangeal length contrasts translated into significant differences in mechanical advantages for the flexor muscles across the MCP and IP articulations.     

Biphalangia of the lateral toes. A study on the incidence in a Swedish population together with some observations on digital sesamoid bones in the foot

The incidence of a two-phalangeal fifth toe in a Swedish population has been investigated in a series of 496 persons. The incidence is about 35% without significant differences between sexes or between age groups. The figure coincides with that found in studies on German, English and Danish populations but differs from that of American and that of Japanese populations. It is concluded that the cause of this anomaly is genetic and that the two-phalangeal fifth toe may be an important parameter in racial studies and for the identification of an individual. Each phalanx in the two-phalangeal toe is on the average almost 5 mm longer than its counterpart in the three-phalangeal variety, resulting in the paradoxic fact that the three-phalangeal toe is shorter on the average than the two-phalangeal one. The numbers of sesamoid bones in various locations of the toes are presented.     

Simultaneous multiple toe transfers in hand reconstruction

Our experience with simultaneous transfer of two or more toe units to the same hand where multiple digits were missing is presented. Forty-six toes from 38 feet were transferred to reconstruct 19 hands in 19 patients. The transfers consisted of 7 combined second and third toe units and 32 single toes. Three patients had a primary and 16 patients had a secondary reconstruction. There was one complete and one partial failure. The two-point discrimination ranged from 6 mm to protective sensation. Total active movement averaged 57 degrees in the thumb and 127, 93, 71, and 68 degrees, respectively, in the fingers reconstructed at middle phalanx, proximal phalanx, metacarpophalangeal joint, and metacarpal head. Pulp-to-pulp pinch averaged 2.4 kg in patients who had thumbs reconstructed and averaged 3.0 kg in patients who had normal thumbs. There was no cold intolerance, and no significantly disabled foot occurred except one with scissoring deformity. Simultaneous multiple toe transfer in hand reconstruction is feasible without increased complications both in primary and secondary wound conditions. It is time-effective and cost-effective.     

Chiropteran tendon locking mechanism

Rather than the usual mammalian scheme in which tendon and sheath surfaces provide as little friction as possible, the tendons and sheaths of many bats have a locking segment on the manual and pedal flexor tendon complex. This tendon locking mechanism (TLM) exists opposite the proximal phalanges of each toe and pollex of many bats. Its structure, similar to a ratchet mechanism, assists bats in hanging with little muscular effort. The third digit of the pelvic limb and the pollex of species representing 15 chiropteran families were studied to determine the presence or absence, morphology, and function of the TLM. Most of the species studied have a TLM consisting of a patch of tubercles on the ventral surface of the flexor tendon associated with the proximal phalanx of each pollex or toe. The sheath adjacent to this portion of the flexor tendon has a series of transverse folds or ridges, which, when engaged with the tubercles on the tendon, lock the tendon in place. The TLM is similar in megachiropterans and microchiropterans possessing it. The TLM is absent, however, in some of the microchiropterans studied, most notably in the phyllostomids. Since many birds have a TLM similar to that of bats, it is an excellent example of the convergent evolution of a feature brought about by similar functional pressures on birds and bats. © 1993 Wiley-Liss, Inc.