The human foot is a biomechanical marvel which forms the distal link in the lower limb kinematic chain. With its small polyarticular construct and flexibility, it supports the body and provides balance during walking. The first metatarsophalangeal joint (MTPJ) is a vital joint in the forefoot for normal load transmission and energy efficient locomotion. Albeit a lot in literature about this joint, paucity still exists in the biomechanical aspects. Also, there is a speculation in the biomechanical world that the time integral component of pressure recorded from the plantar pressure measuring devices maybe representative of the shear force recorded from force platforms. The aim of the current study was to quantify the kinematics of the first MTPJ in three dimensions and the pedobarographic data under the first MTPJ during each sub-phase of stance in the gait cycle of normal subjects and to assess the correlation between the shear force from the force plate of the motion capture system with the variables from the barefoot plantar pressure measuring device. Similar quantification will be undertaken for the patients with isolated hallux rigidus. After obtaining ethical approval, 40 normal subjects (80 feet) and 6 patients with varying grades of hallux rigidus were recruited for the study. The equipment used to collect data included the Vicon® motion analysis system, AMTI® force plate and the emed® plantar pressure measuring device. Various checks were performed to establish the reliability of the system setup. Four trials from each foot were taken. Of the 320 total trials from the normal subjects, the trial numbers varied for specific tasks as some trials which were suitable for testing one objective might not be suitable for testing the other. One of the patients’ data could not be used as the data quality was below par due to issues with marker tracking. The correlation between the shear force from the force plate and the anthropometric measurements/parameters from the plantar pressure measuring device was performed using the statistical regression model. The Vicon® data of the whole stance phase revealed that the first MTPJ’s sagittal plane motion ranged from 9° of plantarflexion to 53° of dorsiflexion. In the coronal plane, the maximum pronation was 34° and supination was 31°. In the transverse plane, the maximum varus was 11° and the valgus was 24°. There were two dorsiflexion peaks; one at the Initial contact and the other at Pre-swing. The joint moved from supination to pronation and varus to valgus during the progression of stance phase from Initial contact to Pre-swing. Considering the emed®-m, there were four basic parameters namely the force, area, peak pressure and maximum mean pressure from which the other parameters were derived. Only the basic parameters accounted for the sub-phases of stance and it came to light that the force under the first MTPJ was maximum in the terminal stance (22.1%). For the whole stance phase, the first MTPJ contributed about 11% of the contact area, 14.5% of the mean area, 24% of the maximum force, 56% of the peak pressure, 63% of maximum mean pressure, 44% of Pressure-time integral, 14% of Force-time integral and 14% of mean force. The correlation equation with reasonable number of dependent variables obtained by the statistical regression model could account for only 46% of the shear force. Among the paired correlation equations with single dependent variable, the one with the mean force was the best and even this could only account for 31.1% of the shear force. Albeit 3 patients were having similar radiological grading of the pathology and 2 others falling into another grade, their objective data were diverse and couldn’t be grouped together. The normal kinematics of the first MTPJ and the pedobarographic data under the first MTPJ were quantified during each subphase of stance. Attempt to use one system alone instead of two to calculate the shear force did not provide satisfactory results. The patients’ data questions the use of radiology alone in deciding the management plan which is a common scenario in the current clinical setting.

[Truncated abstract] Limitation of sagittal plane dorsiflexion, or hallux limitus (HL), represents the second most commonly encountered pathomechanical disorder affecting the first metatarsophalangeal joint, after hallux valgus (HV). The kinematic role of the first metatarsophalangeal joint represents an integral component of the gait cycle. It has often been reported that for adequate leverage and propulsion to occur during normal gait, the hallux must be able to dorsiflex approximately 65° on the head of the first metatarsal. Secondary gait compensation mechanisms have often been observed clinically as a result of HL. The effect of HL on gait can be reflected in transverse plane alteration of the foot in relation to the line of progression during gait, defined as the angle of gait (AOG). The first purpose of this study served to investigate potential differences in dynamic angle of gait AOG in subjects with HL compared to a control group. A validated technique using coloured powdered footprints was used to quantify AOG. Furthermore, it was required to establish whether the relative amount of transverse plane motion observed in the AOG was related to factors intrinsic or extrinsic to the foot. Intrinsic factors such as the amount of forefoot to rearfoot abduction was considered, and achieved by measuring the rearfoot to forefoot axis (RFA) angle using a weight bearing composite (COMP) view radiograph. The remaining objectives of the study served to investigate other common aetiological factors associated with HL and their potential influence on AOG in subjects with HL ... Results further indicated that the amount of first metatarsophalangeal joint dorsiflexion did not appear to influence AOG in the two groups, and that AOG did not reflect the iii amount of forefoot to rearfoot abduction in a foot with HL compared to the control group. When comparing foot type, as indicated by CIA, it appeared AOG did not significantly alter between the HL and control groups. Finally, the results indicated AOG did not differ significantly between subjects with unilateral HL. This thesis study indicated that with the current sample population, the wide variability in AOG prevented detection of any subtle differences that may exist in subjects with HL. Results also emphasised the need to incorporate other variables such as symptomology and foot dominance when considering the effects first metatarsophalangeal joint pathology might have on HL, such as AOG.

The work provides a comprehensive overview of the issues hallux rigidus with a focus on the first metatarsophalangeal joint replacement and development of our own implant. The development was built to perform anatomical studies, the results were the basis for the construction of hemiarthroplasty and total arthroplasty. It was necessary to measure the marrow cavities of the distal part of first metatarsal and proximal half of proximal phalanx. We measured the size of the metatarsal head in two planes, and its tendency to diaphysis on the dry preparations. Through these studies we obtained valid data for the construction all components of both hemiarthroplasty and total arthroplasty of specifying the size spectrum. We have verified and then corrected the shape of implant treatment during post-mortem tests on the models. The result is a new type of arthroplasty with their own design to guarantee restoration of joint function and coated with a high osteointegral potential. In clinical studies, we performed 22 implantations of hemiarthroplasty and one implantation of total arthroplasty. Clinical results suggest the fact that the implant will be successful. However the ultimate answer to this question will provide long-term study. The other results presented with a detailed anatomical description show to...

The work provides a comprehensive overview of the issues hallux rigidus with a focus on the first metatarsophalangeal joint replacement and development of our own implant. The development was built to perform anatomical studies, the results were the basis for the construction of hemiarthroplasty and total arthroplasty. It was necessary to measure the marrow cavities of the distal part of first metatarsal and proximal half of proximal phalanx. We measured the size of the metatarsal head in two planes, and its tendency to diaphysis on the dry preparations. Through these studies we obtained valid data for the construction all components of both hemiarthroplasty and total arthroplasty of specifying the size spectrum. We have verified and then corrected the shape of implant treatment during post-mortem tests on the models. The result is a new type of arthroplasty with their own design to guarantee restoration of joint function and coated with a high osteointegral potential. In clinical studies, we performed 22 implantations of hemiarthroplasty and one implantation of total arthroplasty. Clinical results suggest the fact that the implant will be successful. However the ultimate answer to this question will provide long-term study. The other results presented with a detailed anatomical description show to...