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1.
Orthopadie (Heidelb) ; 53(10): 765-772, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39172177

RESUMO

INTRODUCTION: Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy syndrome of the upper extremities. The carpal tunnel is an osteofibrous canal that is medially bordered by hamulus ossis hamati and pisiform bone, and laterally by scaphoid and trapezoid bones. In this retrospective case-control study, we investigated the relationship between radiologically measured morphometric indices and CTS in female patients. METHODS: Clinical, radiological, and demographic data were collected for 55 hands of 40 female patients diagnosed with CTS and 58 hands of control subjects. Radiological measurements included various morphometric parameters derived from wrist and hand X-rays. Statistical analysis was conducted to assess associations between morphometric indices and CTS. RESULTS: Significant associations were observed between CTS and several morphometric indices, including carpal height, capitate length, palm length, and others. Notably, these values were lower in CTS patients, suggesting a potential link between reduced carpal tunnel volume and increased pressure due to synovial hypertrophy. Additionally, a newly introduced index, Scaphoid Pisiform Width Index (SPWI), showed promise in assessing the proximal part of the carpal tunnel. CONCLUSION: It was found that the values for Capitate length, Carpal height, Palm length, SPWI, and Palmar ratio were lower in the patient group. These results suggested that decreasing volume of the carpal tunnel allows for an easier increase in carpal tunnel pressure due to increased synovial hypertrophy and the carpal bone configuration affects the proximal part of the carpal tunnel, and influences the compression of the median nerve, in female patients.


Assuntos
Síndrome do Túnel Carpal , Humanos , Síndrome do Túnel Carpal/diagnóstico por imagem , Síndrome do Túnel Carpal/patologia , Feminino , Pessoa de Meia-Idade , Adulto , Estudos de Casos e Controles , Estudos Retrospectivos , Radiografia/métodos , Ossos do Carpo/diagnóstico por imagem , Ossos do Carpo/patologia , Idoso , Sensibilidade e Especificidade
2.
J Hand Surg Asian Pac Vol ; 29(5): 467-471, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39205529

RESUMO

We describe a 13-year-old boy with piso-hamate coalition confirmed by X-ray. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed type 1 coalition according to the classification of DeVilliers Minnaar. Piso-hamate coalition is rare, and suspicions should be raised in instances of chronic ulnar-sided wrist pain, particularly in individuals with a history of elevated hand usage, especially amongst athletes engaging in intensive hand grip activities. Surgical resection of the synchondrosis site between the pisiform and the hamate is an efficacious intervention that can mitigate pain. Level of Evidence: Level V (Therapeutic).


Assuntos
Hamato , Pisciforme , Tomografia Computadorizada por Raios X , Humanos , Masculino , Adolescente , Hamato/diagnóstico por imagem , Pisciforme/diagnóstico por imagem , Imageamento por Ressonância Magnética , Articulação do Punho/diagnóstico por imagem , Articulação do Punho/anormalidades , Articulação do Punho/patologia
3.
J Orthop Case Rep ; 14(7): 55-59, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-39035369

RESUMO

Introduction: Enchondroma is a cartilaginous benign tumor of bone with the most common involvement of tubular bones of hands and feet. The triquetrum and pisiform are carpal bones and the enchondroma of the triquetrum and pisiform has not been reported in the literature to the best of our knowledge. Case Report: A 26-year-old male presented with swelling over his right wrist with painful terminal motion. Based on magnetic resonance imaging findings, diagnosis of enchondroma of triquetrum and pisiform was made. Bone excision and curettage were performed, and histopathology confirmed the diagnosis. After 2 years of follow-up, the patient has gained pain-free wrist movements post excision, and there are no signs of recurrence. The Modified Mayo Wrist Score of 75 (fair) improved to 100 (excellent). Conclusion: The surgeon should always keep in mind the possibility of a tumor at the rare site and accurately diagnose the tumor with the help of imaging modalities and biopsy.

4.
Trauma Case Rep ; 52: 101039, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38799028

RESUMO

A 31-year-old woman had a seizure episode three weeks before, leading to a fall on her left hand. Following the accident, she had discomfort on the ulnar side of her left wrist. She decided to seek treatment from a local bone setter; however, her hand discomfort continued and she then came to us for treatment. The radiography and computed tomography scan demonstrated a pisiform dislocation. The pisiform bone was surgically removed. The pisiform dislocation should be considered in the differential diagnosis of the ulnar side wrist discomfort following wrist trauma.

5.
Medicina (Kaunas) ; 60(4)2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38674178

RESUMO

We present the case of a 14-year-old patient who suffered fracture dislocation of the pisiform bone (PB) along with fractures of the scaphoid, proximal radius, and proximal phalanx of the thumb due to high-energy trauma directly to the extended wrist. This combination of fractures has not been previously reported in the literature. Currently, there is no consensus in the literature regarding the optimal treatment approach for such cases. In our management, initial attempts at closed and open reduction were unsuccessful, leading to the decision for primary pisiformectomy. Our report includes a follow-up of 3.5 years, demonstrating a very good outcome. Based on this case and a few similar published cases, primary pisiformectomy appears to be a viable and well-accepted option, particularly among young patients. Additionally, we conducted a review of radiographic criteria and management strategies for this specific injury and related conditions.


Assuntos
Pisciforme , Humanos , Adolescente , Masculino , Pisciforme/lesões , Fratura-Luxação/cirurgia , Fratura-Luxação/diagnóstico por imagem , Fraturas Ósseas/diagnóstico por imagem , Fraturas Ósseas/cirurgia , Traumatismos do Punho/cirurgia , Traumatismos do Punho/diagnóstico por imagem
6.
Cureus ; 16(3): e56001, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38606251

RESUMO

Background The carpal tunnel is a groove that spans the palm as a 'U.' The ulnar and radial sides of the wrist are made up of the scaphoid tubercle and trapezium while the palmar aspect is made up of carpal bones. Our study aimed to see whether there were differences in carpal tunnel size between men and women. Material and methods The study was conducted on 65 healthy adults, 13 (20%) were males and 52 (80%) were females (both non-pregnant and pregnant). Inclusion criteria were healthy adults and bilaterally symmetrical limbs. Exclusion criteria were chronic disease, diabetes, hypertension, immunological disorders, any visible abnormalities, and a history of upper extremity pain on either side. A high-resolution ultrasound machine with a linear transducer was used to perform an ultrasound scan of the carpal tunnel. The anteroposterior dimension was measured at the midline, or along the axis of the middle finger, and the transverse diameter was measured at the midpoint of the flexor retinaculum. The cross-sectional area of the tunnel was measured at its largest diameter within the carpal tunnel. All the dimensions were measured in centimeters. Results The mean transverse diameter of the right side was 1.824 ± 0.223 cm (p-value 0.002) and of the left side was 1.742 ± 0.197 cm (p-value 0.004). The mean cross-sectional area of the carpal tunnel on the right side was 1.417 ± 0.379 cm2 (p-value 0.008) and on the left side was 1.306 ± 0.303 cm2 (p-value 0.004), respectively. Age, sex, weight, and BMI were discussed. The carpal tunnels of females were found to be comparatively squarer and smaller than those of males. Conclusion The transverse diameter and cross-sectional area of the carpal tunnel and their correlation with carpal tunnel syndrome are predicted by age, sex, weight, and BMI. Both sexes had the same wrist ratio.

7.
JPRAS Open ; 39: 132-141, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38259863

RESUMO

Although various treatments for advanced stages of Kienböck's disease have been reported, clinical evidence demonstrating the efficacy of lunate resection and vascularized os pisiform transfer for Kienböck's disease is limited. Herein, we investigated the clinical and radiographic results of this procedure. We retrospectively investigated eight patients who were followed up for ≥1 year. The mean age at the time of surgery was 52 years. The mean follow-up period was 3.4 years. The preoperative and postoperative mean wrist flexion-extension ranges were 84° and 111°, respectively, and grip strengths were 18.5 and 26.3 kg, respectively. Pain decreased in five patients postoperatively. The mean preoperative and postoperative carpal height ratios were 0.47 and 0.46, respectively, and radio scaphoid angles were 63° and 65°, respectively. Osteoarthritic changes were observed in or around the transferred pisiform in all five patients who were surveyed using radiographs. Most patients demonstrated satisfactory clinical results, including pain relief and improved wrist motion and grip strength, regardless of osteoarthritic wrist changes on postoperative radiographs. In summary, this procedure was effective for treating Kienböck's disease, especially in the advanced stages. Level of evidence: Ⅳ.

8.
Cureus ; 15(9): e46042, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37900515

RESUMO

Isolated pisiform dislocation is an uncommon condition, with a limited number of cases reported in the literature. We present a unique case of a 15-year-old male who experienced an atraumatic isolated dislocation of the pisiform bone in his left wrist and presented with pain, deformity, and ulnar nerve palsy in his little and ring fingers. Radiographic investigations confirmed the diagnosis of isolated pisiform dislocation, and the patient successfully underwent an open reduction, stabilization of pisiform, and exploration of the ulnar nerve.

9.
J Wrist Surg ; 12(4): 331-336, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37564611

RESUMO

Background Pisotriquetral pain and instability is an elusive cause of ulnar-sided wrist pain. Initial treatment of chronic pisotriquetral pathology should involve a trial of nonoperative therapy such as neutral wrist splint, anti-inflammatories, and intra-articular steroid injections. The mainstay of surgical management of pisotriquetral pain is pisiform excision. Purpose This prospective study seeks to understand patient satisfaction after pisiform excision in patients with isolated pisotriquetral pathology. Patients and Methods A consecutive series of nine cases of pisiform excision was performed by the senior surgeon. The primary outcome measure was determined a priori to be the Patient-Rated Wrist Evaluation (PRWE) score. Wrist range of motion, grip strength, and QuickDASH (shortened version of Disabilities of the Arm, Shoulder and Hand) scores were also collected preoperatively and at 3 and 12 months postoperatively as secondary outcome measures. Results There was a very rapid improvement in the PRWE by 3 months, which was maintained at 12 months. The QuickDASH score was slower to improve, with a significant improvement by 12 months. There was no change in grip strength or wrist range of motion at any time point. Conclusion Pisiform excision results in a very rapid improvement of symptoms and should be considered in cases of pisotriquetral instability or arthritis that fail conservative management. Level of Evidence Level IV, case series.

10.
Acta Radiol ; 64(1): 250-256, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35108123

RESUMO

BACKGROUND: Ulnar-sided wrist pain is associated with the development of multiple wrist pathologies. But the anatomical etiologies have not been fully understood. PURPOSE: To determine the association of three anatomical factors with ulnar-sided wrist pain, including ulnar variance (UV), distal ulnar volar angle (DUVA), and pisiform-ulnar distance (PUD). MATERIAL AND METHODS: A total of 64 patients who had ulnar-sided wrist pain associated with training injuries were retrospectively studied. A control group included 64 healthy athletes from the same unit. The UV, DUVA, and PUD of each individual was measured on radiographs. RESULTS: The average UV and DUVA of those in the ulnar-sided pain group were 0.84 mm and 174.65°, respectively; the control group values were 0.39 mm and 175.11°. The differences between the two groups had no statistical significance (P > 0.05). The average PUD of the ulnar-sided wrist pain group was shorter than that of the control group (2.37 cm vs. 2.65 cm); the difference had statistical significance (P < 0.05). PUD had a negative correlation with ulnar-sided pain; it was an anatomical protective factor (odds ratio = 0.01; P < 0.00; 95% confidence interval=0.00-0.05). Both UV and DUVA had no significant correlations with ulnar-sided wrist pain (P > 0.05). CONCLUSION: PUD has a significant correlation with ulnar-sided wrist pain. It is the anatomical protective factor. Both the UV and DUVA have no statistical association with ulnar-sided wrist pain, but we cannot ignore their potential pathogenic effects on wrists, and further studies are needed to confirm the results.


Assuntos
Traumatismos do Punho , Punho , Humanos , Punho/diagnóstico por imagem , Estudos Retrospectivos , Traumatismos do Punho/complicações , Traumatismos do Punho/diagnóstico por imagem , Artralgia/etiologia , Artralgia/complicações , Ulna/diagnóstico por imagem , Ulna/lesões , Dor , Articulação do Punho/diagnóstico por imagem
11.
J Hand Microsurg ; 14(4): 339-342, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36398158

RESUMO

Traumatic dislocation of the pisiform bone (PB) is a rare injury of the carpal bones, especially in pediatric patients. A few cases were reported, and there is no consensus about the treatment. Each author supports his own method, such as an open reduction internal fixation (ORIF) approach or a closed reduction. However, failures of both techniques with recurrent dislocation of the PB have been reported in the literature. In this article, a fracture dislocation of the PB was treated with ORIF in an 11-year-old boy with a greenstick radial fracture. In addition, a review of the literature about pisiform fracture dislocation in children has been made.

12.
Orthop Rev (Pavia) ; 14(3): 32339, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35775039

RESUMO

The authors present a case of a triquetrum fracture and pisiform dislocation diagnosed in the emergency department. The patient described wrist pain with no other complaints. However, after a plain radiograph in the emergency department, a minimally displaced avulsion fracture of the triquetrum and subtle pisiform dislocation was detected. The patient was placed in a forearm volar splint upon consultation with an orthopedist. Careful examination is imperative given the rarity of an associated pisiform dislocation.

13.
Genes (Basel) ; 13(7)2022 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-35885978

RESUMO

The human capacity to speak is fundamental to our advanced intellectual, technological and social development. Yet so very little is known regarding the evolutionary genetics of speech or its relationship with the broader aspects of evolutionary development in primates. In this study, we describe a large family with evolutionary retrograde development of the larynx and wrist. The family presented with severe speech impairment and incremental retrograde elongations of the pisiform in the wrist that limited wrist rotation from 180° to 90° as in primitive primates. To our surprise, we found that a previously unknown primate-specific gene TOSPEAK had been disrupted in the family. TOSPEAK emerged de novo in an ancestor of extant primates across a 540 kb region of the genome with a pre-existing highly conserved long-range laryngeal enhancer for a neighbouring bone morphogenetic protein gene GDF6. We used transgenic mouse modelling to identify two additional GDF6 long-range enhancers within TOSPEAK that regulate GDF6 expression in the wrist. Disruption of TOSPEAK in the affected family blocked the transcription of TOSPEAK across the 3 GDF6 enhancers in association with a reduction in GDF6 expression and retrograde development of the larynx and wrist. Furthermore, we describe how TOSPEAK developed a human-specific promoter through the expansion of a penta-nucleotide direct repeat that first emerged de novo in the promoter of TOSPEAK in gibbon. This repeat subsequently expanded incrementally in higher hominids to form an overlapping series of Sp1/KLF transcription factor consensus binding sites in human that correlated with incremental increases in the promoter strength of TOSPEAK with human having the strongest promoter. Our research indicates a dual evolutionary role for the incremental increases in TOSPEAK transcriptional interference of GDF6 enhancers in the incremental evolutionary development of the wrist and larynx in hominids and the human capacity to speak and their retrogression with the reduction of TOSPEAK transcription in the affected family.


Assuntos
Fator 6 de Diferenciação de Crescimento , Fala , Animais , Evolução Biológica , Fator 6 de Diferenciação de Crescimento/genética , Fator 6 de Diferenciação de Crescimento/metabolismo , Humanos , Camundongos , Primatas/genética , Sequências Reguladoras de Ácido Nucleico
14.
Rev Bras Ortop (Sao Paulo) ; 57(2): 341-344, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35652023

RESUMO

Isolated pisiform dislocation is a rare lesion with few cases described in the literature. This type of lesion is typically observed in young males and can be easily overlooked at first assessment. Isolated proximal dislocation is more common due to the action of the flexor carpi ulnaris (FCU) muscle. We present the case of a 19-year-old male patient with isolated distal pisiform dislocation after wrist trauma. He underwent open reduction and internal fixation with Kirschner wires with excellent functional outcomes. Although there is no consensual therapeutic method, closed reduction is a first-line treatment for acute presentations. Pisiform open reduction or excision may be performed alternatively or after a failed closed reduction.

15.
J Radiol Case Rep ; 16(4): 1-10, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35530418

RESUMO

The pisiform is a sesamoid bone that acts as one of the key medial stabilizers of the wrist. We present a case of a 35-year-old gentleman who presented with medial wrist pain following a fall while rollerblading. Radiographs and Magnetic resonance imaging (MRI) revealed a rare combination of an acute pisiform dislocation with associated triquetral fracture. Subsequently, he was successfully treated with excision of the pisiform. Pisiform dislocation is an uncommon injury and can easily be missed in an acute emergency presentation. Therefore, it is important to be aware of the characteristic imaging appearance to avoid a delay in diagnosis and treatment.


Assuntos
Luxações Articulares , Pisciforme , Acidentes por Quedas , Adulto , Humanos , Luxações Articulares/diagnóstico por imagem , Luxações Articulares/cirurgia , Masculino , Pisciforme/diagnóstico por imagem , Pisciforme/lesões , Pisciforme/cirurgia , Radiografia , Articulação do Punho
16.
Rev. Bras. Ortop. (Online) ; 57(2): 341-344, Mar.-Apr. 2022. graf
Artigo em Inglês | LILACS | ID: biblio-1387987

RESUMO

Abstract Isolated pisiform dislocation is a rare lesion with few cases described in the literature. This type of lesion is typically observed in young males and can be easily overlooked at first assessment. Isolated proximal dislocation is more common due to the action of the flexor carpi ulnaris (FCU) muscle. We present the case of a 19-year-old male patient with isolated distal pisiform dislocation after wrist trauma. He underwent open reduction and internal fixation with Kirschner wires with excellent functional outcomes. Although there is no consensual therapeutic method, closed reduction is a first-line treatment for acute presentations. Pisiform open reduction or excision may be performed alternatively or after a failed closed reduction.


Resumo A luxação isolada do pisiforme é uma lesão rara com poucos casos descritos na literatura. Esse tipo de lesão é observado tipicamente em adultos jovens do sexo masculino e pode ser facilmente negligenciada numa primeira avaliação. A luxação proximal isolada é mais comum devido à ação do flexor ulnar do carpo (FUC). Apresentamos o caso de um paciente do sexo masculino, com 19 anos de idade, com luxação distal isolada do pisiforme após traumatismo do punho. O paciente foi submetido a uma redução aberta e fixação interna com fios de Kirschner com excelente resultado funcional. Apesar de não existir um método de tratamento consensual, a redução fechada perfila-se como tratamento de primeira linha na apresentação aguda. Em caso de insucesso ou como método alternativo pode-se optar pela redução aberta ou a excisão do pisiforme.


Assuntos
Humanos , Masculino , Adulto , Traumatismos do Punho , Ossos do Carpo/lesões , Luxações Articulares , Pisciforme
17.
Diagnostics (Basel) ; 12(3)2022 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-35328244

RESUMO

Background: We investigated whether opportunistic screening for osteoporosis can be done from computed tomography (CT) scans of the wrist/forearm using machine learning. Methods: A retrospective study of 196 patients aged 50 years or greater who underwent CT scans of the wrist/forearm and dual-energy X-ray absorptiometry (DEXA) scans within 12 months of each other was performed. Volumetric segmentation of the forearm, carpal, and metacarpal bones was performed to obtain the mean CT attenuation of each bone. The correlations of the CT attenuations of each of the wrist/forearm bones and their correlations to the DEXA measurements were calculated. The study was divided into training/validation (n = 96) and test (n = 100) datasets. The performance of multivariable support vector machines (SVMs) was evaluated in the test dataset and compared to the CT attenuation of the distal third of the radial shaft (radius 33%). Results: There were positive correlations between each of the CT attenuations of the wrist/forearm bones, and with DEXA measurements. A threshold hamate CT attenuation of 170.2 Hounsfield units had a sensitivity of 69.2% and a specificity of 77.1% for identifying patients with osteoporosis. The radial-basis-function (RBF) kernel SVM (AUC = 0.818) was the best for predicting osteoporosis with a higher AUC than other models and better than the radius 33% (AUC = 0.576) (p = 0.020). Conclusions: Opportunistic screening for osteoporosis could be performed using CT scans of the wrist/forearm. Multivariable machine learning techniques, such as SVM with RBF kernels, that use data from multiple bones were more accurate than using the CT attenuation of a single bone.

18.
Ann Med Surg (Lond) ; 74: 103259, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35145657

RESUMO

OBJECTIVES: Several studies have been conducted on the variations and branching pattern of the ulnar nerve in the hand. There are few studies conducted on defining the distance of ulnar nerve from bony landmarks in the palm. Ulnar nerve is closely related to the pisiform and hook of hamate which act as important landmarks. METHODS: The study was conducted on 30 formalin fixed adult hand specimens in the department of Anatomy. Various measurements related to the ulnar nerve in the palm were taken using a divider and Vernier Calipers and the values were tabulated after obtaining the mean and standard deviation. RESULTS: The average distance seen in the hand specimens [n = 30] from pisiform to the division of ulnar nerve into superficial and deep branch was 0.89 ± 0.25cm and the distance between pisiform bone up to the division of superficial branch of ulnar nerve into proper and common digital branches was 1.36 ± 0.59 cm. The average distance from the origin of proper digital branch of ulnar nerve to the head of fifth metacarpal bone was 5.25 ± 0.59 cm. The length of common digital branch of ulnar nerve from its origin to division into 2 sensory branches was 4.31 ± 1.09 cm. CONCLUSION: This study provides the metric parameters of the ulnar nerve in the hand from its significant bony landmarks which should be kept in mind during surgical procedures to minimize the incidence of injury to its branches. It would assist the orthopedic surgeon in the treatment of ulnar nerve compression in the Guyon's canal.

19.
Skeletal Radiol ; 51(8): 1687-1694, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35079865

RESUMO

PURPOSE: To describe our techniques for ultrasound-guided injection of the pisotriquetral joint (PTJ), and to report our experience in a case series. METHODS: Between 7/1/14 and 11/30/20, we performed 42 injections in 33 patients with ulnar-sided wrist pain, referred by clinicians who suspected the PTJ as the pain generator. There were 16 males and 17 females, average age 46.7 years. The patients were positioned in one of five ways: sitting with the hand maximally supinated; sitting with the hand maximally pronated; supine with the elbow flexed across the chest and the ulnar aspect of the wrist facing upward; supine with the elbow flexed, the arm externally rotated, and the ulnar aspect of the wrist facing upward; prone with the symptomatic hand at their side and the ulnar aspect of the wrist facing upward. RESULTS: The procedures were performed by any of twelve fellowship-trained musculoskeletal radiologists. Fifteen patients reported immediate relief of symptoms, including 6 patients whose pisotriquetral joints were normal sonographically. Four patients underwent subsequent surgical excision of their pisiforms and the fifth underwent arthroscopic debridement of the pisotriquetral joint. CONCLUSION: Ultrasound is a facile imaging modality for guiding pisotriquetral injections, which may be accomplished with a variety of patient positions and injection techniques.


Assuntos
Articulações do Carpo , Pisciforme , Artralgia/diagnóstico por imagem , Artralgia/tratamento farmacológico , Artralgia/etiologia , Articulações do Carpo/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pisciforme/diagnóstico por imagem , Ultrassonografia de Intervenção , Articulação do Punho/diagnóstico por imagem , Articulação do Punho/cirurgia
20.
Anat Rec (Hoboken) ; 305(7): 1804-1819, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-34779120

RESUMO

Two-toed (Choloepus sp.) and three-toed (Bradypus sp.) sloths possess short, rounded pisiforms that are rare among mammals and differ from other members of Xenarthra like the giant anteater (Myrmecophaga tridactyla) which retain elongated, rod-like pisiforms in common with most mammals. Using photographs, radiographs, and µCT, we assessed ossification patterns in the pisiform and the paralogous tarsal, the calcaneus, for two-toed sloths, three-toed sloths, and giant anteaters to determine the process by which pisiform reduction occurs in sloths and compare it to other previously studied examples of pisiform reduction in humans and orangutans. Both extant sloth genera achieve pisiform reduction through the loss of a secondary ossification center and the likely disruption of the associated growth plate based on an unusually porous subchondral surface. This represents a third unique mechanism of pisiform reduction among mammals, along with primary ossification center loss in humans and retention of two ossification centers with likely reduced growth periods in orangutans. Given the remarkable similarities between two-toed and three-toed sloth pisiform ossification patterns and the presence of pisiform reduction in fossil sloths, extant sloth pisiform morphology does not appear to represent a recent convergent adaptation to suspensory locomotion, but instead is likely to be an ancestral trait of Folivora that emerged early in the radiation of extant and fossil sloths.


Assuntos
Bichos-Preguiça , Xenarthra , Animais , Fósseis , Humanos , Mamíferos , Osteogênese , Bichos-Preguiça/anatomia & histologia
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