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Biomedical subjects

J G Buckley

Publications and source records attributed to J G Buckley.

At least 19 recordsLinked to original sources
PubMed2005

The mechanics of landing when stepping down in unilateral lower-limb amputees.

BACKGROUND: The ability to successfully negotiate stairs and steps is an important factor for functional independence. While work has been undertaken to understand the biomechanics of gait in lower-limb amputees, little is known about how amputees negotiate stairs and steps. This study aimed to determine the mechanics of landing in unilateral lower-limb amputees when stepping down to a new level. A secondary aim was to assess the effects of using a shank-mounted shock-absorbing device (Tele-Torsion Pylon) on the mechanics of landing. METHODS: Ten unilateral amputees (five transfemoral and five transtibial) and eight able-bodied controls performed single steps down to a new level (73 and 219 mm). Trials were repeated in amputees with the Tele-Torsion Pylon active and inactive. The mechanics of landing were evaluated by analysing peak limb longitudinal force, maximal limb shortening, lower extremity stiffness, and knee joint angular displacement during the initial contact period, and limb and ankle angle at the instant of ground-contact. Data were collected using a Vicon 3D motion analysis system and two force platforms. FINDINGS: Amputees landed on a straightened and near vertical limb. This limb position was maintained in transfemoral amputees, whereas in transtibial amputees knee flexion occurred. As a result lower extremity stiffness was significantly greater in transfemoral amputees compared to transtibial amputees and able-bodied controls (P<0.001). The Tele-Torsion Pylon had little effect on the mechanics of landing in transtibial amputees, but brought about a reduction in lower extremity stiffness in transfemoral amputees (P<0.05). INTERPRETATION: Amputees used a stepping strategy that ensured the direction of the ground reaction force vector was kept anterior of the knee joint centre. Using a Tele-Torsion Pylon may improve the mechanics of landing during downward stepping in transfemoral amputees.

Adult↗
PubMed2005

The gait initiation process in unilateral lower-limb amputees when stepping up and stepping down to a new level.

BACKGROUND: Unilateral lower-limb amputees lead with their intact limb when stepping up and with their prosthesis when stepping down; the gait initiation process for the different stepping directions has not previously been investigated. METHODS: Ten unilateral amputees (5 transfemoral and 5 transtibial) and 8 able-bodied controls performed single steps up and single steps down to a new level (73 and 219 mm). Duration, a-p and m-l centre of mass and centre of pressure peak displacements and centre of mass peak velocity of the anticipatory postural adjustment and step execution phase were evaluated for each stepping direction by analysing data collected using a Vicon 3D motion analysis system. FINDINGS: There were significant differences (in the phase duration, peak a-p and m-l centre of pressure displacement and peak a-p and m-l centre of mass velocity at heel-off and at foot-contact) between both amputee sub-groups and controls (P<0.05), but not between amputee sub-groups. These group differences were mainly a result of amputees adopting a different gait initiation strategy for each stepping direction. INTERPRETATION: Findings indicate the gait initiation process utilised by lower-limb amputees was dependent on the direction of stepping and more particularly by which limb the amputee led with; this suggests that the balance and postural control of gait initiation is not governed by a fixed motor program, and thus that becoming an amputee will require time and training to develop alternative neuromuscular control and coordination strategies. These findings should be considered when developing training/rehabilitation programs.

Adult↗
PubMed2005

Chronic low back pain in traumatic lower limb amputees.

OBJECTIVE: To ascertain the prevalence of back pain amongst traumatic lower limb amputees attending a regional rehabilitation centre and to determine the possible causes of back pain. DESIGN: All traumatic lower limb amputees given a semi-structured questionnaire to complete and a comparative subgroup of amputees with back pain and without back pain underwent physical examination, gait analysis, magnetic resonance scanning (MRI) and gait/standing stability analysis. SETTING: A subregional amputee rehabilitation centre. RESULTS: Transfemoral amputees were more likely to suffer from back pain (81 %) than transtibial amputees (62%) (p<0.05) and of those suffering from severe back pain, 89% and 81% also suffered from severe pain in the phantom limb and severe stump pain respectively. In two comparative subgroups of amputees there was no significant difference between back pain and pain-free groups except those with pain were more likely to have a body mass index (BMI) ratio above 50% of the recommended ratio. No difference in degeneration or disc disease between the groups on MR scans was found. Impact ground reaction forces during walking, irrespective of limb, were significantly greater (p < 0.05) in the pain-free group than in the pain group, as was walking speed. Gait asymmetry measures were similar in both groups. Centre of pressure displacement measures during standing were greater in the pain group than in the pain-free group. CONCLUSIONS: Low back pain in amputees is a significant problem equal to that of pain in the phantom limb and a biomechanical (myofascial) rather than a degenerative aetiology is suggested.

Adolescent↗
PubMed2001

Surgical treatment of cervical node metastases from squamous carcinoma of the upper aerodigestive tract: evaluation of the evidence for modifications of neck dissection.

BACKGROUND: This review article examines the role of the different types of neck dissection in the treatment of squamous carcinoma metastases to the cervical nodes. METHODS: A critical evaluation of the literature on the pathologic basis, oncologic effectiveness, and functional outcome of neck dissection. RESULTS: Pathologic data show preferential metastasis to different lymph node levels, in N0- and N+-staged disease, depending on the primary tumor site. Comparative studies on control of regional metastases suggest that modified radical is no less effective than radical neck dissection, but there is insufficient data to draw firm conclusions on the role of selective neck dissection. Selective and modified radical dissections result in less shoulder disability than radical neck dissection. CONCLUSIONS: Modified radical neck dissection is supported by pathologic and clinical evidence in N1- and 2-staged disease. There may be a role for selective dissection, but there is a need for more information on oncologic outcome. Prospective multicenter systematic data collection on the outcome of neck dissection is a pragmatic alternative to a trial.

Carcinoma, Squamous Cell↗
PubMed2001

Muscle power patterns in the mid-acceleration phase of sprinting.

To assess the role of the lower limb joints in generating velocity in the mid-acceleration phase of sprinting, muscle power patterns of the hip, knee and ankle were determined. Six male sprinters with a mean 100 m time of 10.75 s performed repeated maximal sprints along a 35 m indoor track. A complete stride across a force platform, positioned at approximately 14 m into the sprint, was video-recorded for analysis. Smoothed coordinate data were obtained from manual digitization of (50 Hz) video images and were then interpolated to match the sampling rate of the recorded ground reaction force (1000 Hz). The moment at each joint was then calculated using inverse dynamics and multiplied by the angular velocity to determine the muscle power. The results showed a proximal-to-distal timing in the generation of peak extensor power during stance at the hip, the knee and then the ankle, with the plantar flexors producing the greatest peak power. Apart from a moderate power generation peak towards toe-off, knee power was negligible despite a large extensor moment throughout stance. The role of the knee thus appears to be one of maintaining the centre of mass height and enabling the power generated at the hip to be transferred to the ankle.

Acceleration↗
PubMed2000

Cancer spread in the larynx: a pathologic basis for conservation surgery.

BACKGROUND: Previous pathologic studies of the spread of laryngeal carcinoma have drawn inferences about the site of origin of tumors, their mechanisms of growth, or the role of structures as potential barriers to tumor spread. Most of the information is based on the study of advanced or recurrent tumors and is difficult to apply to conservation surgical technique. We carried out a systematic analysis of a wide range of laryngeal tumors with the aim of providing a basis for conservation surgery. METHODS: We analyzed tumor invasion of the laryngeal spaces and the laryngeal framework in relation to the mucosal tumor extent by axial sectioning of 80 sequential partial and total laryngectomy specimens. RESULTS: Invasion of a particular laryngeal space could be accurately predicted by mucosal tumor extent and vocal cord mobility. Invasion of the laryngeal framework was associated with tumor extension to the ventricle, subglottis, or pyriform fossa. The thyroid cartilage and the cricothyroid space and ligament were the most frequent sites of invasion. CONCLUSIONS: The mucosal distribution of a tumor and observation of vocal cord mobility can be used to determine accurately the extent of tumor invasion of the laryngeal spaces and framework and therefore the extent of resection necessary.

Biopsy, Needle↗
PubMed2000

Cervical node metastases in laryngeal and hypopharyngeal cancer: a prospective analysis of prevalence and distribution.

BACKGROUND: We have prospectively analyzed the prevalence and distribution of histologic cervical node metastases in laryngeal and hypopharyngeal squamous carcinoma to determine the most appropriate form of neck dissection. METHODS: We have examined specimens from 100 consecutive patients in whom neck dissection was part of the primary treatment of laryngeal and hypopharyngeal carcinoma. Fifty eight patients were treated by unilateral or bilateral selective dissection of levels I to IV +/- VI for N0 disease and 42 by comprehensive dissection for N+ disease. Assessment was by separation of the specimens into node levels at the time of surgery and embedding all the resected material for histologic analysis. RESULTS: Nodal metastases were found in 36% of ipsilateral and 27% of contralateral dissections in the N0 cases. The corresponding prevalences in N+ cases were 90% and 37%, respectively. All metastases in N0 and N1 disease were confined to levels II, III, IV, and VI. Metastases to levels I and V were infrequent even in N+ disease. CONCLUSIONS: Our results support the use of elective dissection of node levels II to IV for N0 laryngeal and hypopharyngeal carcinoma. We suggest the inclusion of level VI nodes for tumors invading the subglottis, pyriform fossa apex, and postcricoid region. The prevalence of bilateral metastases is great enough in midline or bilateral tumors to justify bilateral selective dissection. It is possible that selective neck dissection is also adequate for small palpable metastases, but greater numbers are required to confirm this.

Carcinoma, Squamous Cell↗
PubMed2000

Biomechanical adaptations of transtibial amputee sprinting in athletes using dedicated prostheses.

OBJECTIVE: To determine the biomechanical adaptations of the prosthetic and sound limbs in two of the world's best transtibial amputee athletes whilst sprinting. DESIGN: Case study design, repeated measures. BACKGROUND: Using dedicated sprint prostheses transtibial amputees have run the 100 m in a little over 11 s. Lower-limb biomechanics when using such prostheses have not previously been investigated. METHODS: Moments, muscle powers and the mechanical work done at the joints of the prosthetic and sound limbs were calculated as subjects performed repeated maximal sprint trials using a Sprint Flex or Cheetah prosthesis. RESULTS: An increased hip extension moment on the prosthetic limb, with an accompanying increase in the amount of concentric work done, was the most notable adaptation in Subject 1 using either prosthesis. In Subject 2, an increased extension moment at the residual knee, and an accompanying increase in the amount of total work done, was the most notable adaptation using either prosthesis. This later adaptation was also evident in Subject 1 when using his Sprint Flex prosthesis. CONCLUSIONS: Increased hip work on the prosthetic limb has previously been shown to be the major compensatory mechanism that allow transtibial amputees to run. The increased work found at the residual knee, suggests that the two amputee sprinters used an additional compensatory mechanism. RELEVANCE: These findings provide an insight into the biomechanical adaptations that allow a transtibial amputee to attain the speeds achieved when sprinting.

Adaptation, Physiological↗
PubMed1999

Sprint kinematics of athletes with lower-limb amputations.

OBJECTIVE: To determine and compare the kinematics of the sound and prosthetic limb in five of the world's best unilateral amputee sprinters. SUBJECTS: Five men, all unilateral lower-limb amputee (one transfemoral, four transtibial) athletes. The individual with transfemoral amputation used a Endolite Hi-activity prosthesis incorporating a CaTech hydraulic swing and stance control unit, a Flex-Foot Modular III, and an ischial containment total contact socket. Those with transtibial amputations used prostheses incorporating a Flex-Foot Modular III and patellar tendon-bearing socket, with silicone sheath liner (Iceross) and lanyard suspension. DESIGN: Case series. Subjects were videotaped sprinting through a performance area. Sagittal plane lower-limb kinematics derived from manual digitization (at 50 Hz) of the video were determined for three sprint trials of the prosthetic and sound limb. Hip, knee, and ankle kinematics of each subject's sound and prosthetic limb were compared to highlight kinematic alterations resulting from the use of individual prostheses. Comparisons were also made with mean data from five able-bodied men who had similar sprinting ability. RESULTS: Sound limb hip and knee kinematics in all subjects with amputation were comparable to those in able-bodied subjects. The prosthetic knee of the transfemoral amputee athlete fully extended early in swing and remained so through stance. In the transtibial amputee athletes, as in able-bodied subjects, a pattern of stance flexion-extension was evident for both limbs. During stance, prosthetic ankle angles of the transtibial amputee subjects were similar to those of the sound side and those of able-bodied subjects. CONCLUSION: Prosthetic limb kinematics in transtibial amputee subjects were similar to those for the sound limb, and individuals achieved an "up-on-the-toes" gait typical of able-bodied sprinting. Kinematics for the prosthetic limb of the transfemoral amputee subject were more typical of those seen for walking. This resulted in a sprinting gait with large kinematic asymmetries between contralateral limbs.

Adult↗
PubMed1999

Fine needle cytology of palpable head and neck lesions: a comparison of sampling methods with and without suction.

Patients attending the ear, nose and throat (ENT) department at St James's University Hospital, Leeds, UK, for evaluation of palpable head and neck lesions have a fine needle cytology (FNC) specimen taken and receive the result at the same out-patient visit. This study was designed to discover if there is a significant difference in the efficiency of the methods with and without suction. The method was chosen randomly on each occasion and the adequacy or otherwise of the specimen was determined taking into account the site and nature of the lesion and the total cellularity of the sample. The level of blood contamination was also compared by each method. When benign and malignant lesions from all sites were analysed together the method with suction produced a significantly higher number of adequate samples than the method without suction. The exception was in the case of samples from lymph node lesions measuring < 1 cm, where adequate specimens were only obtained without suction. The non-suction technique was particularly poor at sampling salivary gland lesions in the 1-1.5 cm category. There was no significant difference in the level of blood contamination between the two methods at any site. These results are at variance with most other similar studies and possible reasons for this are discussed.

Adolescent↗