Objective This scoping review examines how different levels and types of partial foot amputation affect gait and explores how these findings may affect the minimal impairment criteria for wheelchair tennis.
Methods Four databases (PubMed, Embase, CINAHL and SPORTDiscus) were systematically searched in February 2021 for terms related to partial foot amputation and ambulation. The search was updated in February 2022. All study designs investigating gait-related outcomes in individuals with partial foot amputation were included and independently screened by two reviewers based on Arksey and O’Malley’s methodological framework and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews.
Results Twenty-nine publications with data from 252 participants with partial foot amputation in 25 studies were analysed. Toe amputations were associated with minor gait abnormalities, and great toe amputations caused loss of push-off in a forward and lateral direction. Metatarsophalangeal amputations were associated with loss of stability and decreased gait speed. Ray amputations were associated with decreased gait speed and reduced lower extremity range of motion. Transmetatarsal amputations and more proximal amputations were associated with abnormal gait, substantial loss of power generation across the ankle and impaired mobility.
Conclusions Partial foot amputation was associated with various gait changes, depending on the type of amputation. Different levels and types of foot amputation are likely to affect tennis performance. We recommend including first ray, transmetatarsal, Chopart and Lisfranc amputations in the minimum impairment criteria, excluding toe amputations (digits two to five), and we are unsure whether to include or exclude great toe, ray (two to five) and metatarsophalangeal amputations.
Trial registration The protocol of this scoping review was previously registered at the Open Science Framework Registry (https://osf.io/8gh9y) and published.
- Athletic Performance
- Disabled Persons
- Gait analysis
- Sports medicine
- Para sport
- partial foot amputation
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- Athletic Performance
- Disabled Persons
- Gait analysis
- Sports medicine
- Para sport
- partial foot amputation
What is already known on this topic
Partial foot amputation is associated with gait pattern impairments, including spatiotemporal, kinetic and kinematic gait characteristics, ground reaction force and centre of pressure excursion.
Athletes with a partial foot amputation are eligible for Para archery, Para athletics, Para badminton, Para cycling, Para rowing, Para swimming, Para table tennis, Para taekwondo, sitting volleyball and wheelchair tennis. Athletes with partial foot amputation are excluded from the remaining 18 Paralympic sports.
What are the findings?
This review provides a consolidated overview of the gait pattern impairments associated with different levels and types of partial foot amputation.
How might it impact on clinical practice in the future?
Results of this review indicate how different levels and types of foot amputation are likely to affect tennis performance and may be used as supporting evidence for determining minimum impairment criteria for wheelchair tennis.
Lower extremity amputation can negatively impact the quality of life1 2 and is associated with higher morbidity and mortality.3 4 People with limb amputations benefit from participating in regular physical activity and sports and should be encouraged to live a physically active life.5 However, barriers to participating in physical activity and sports include functional limitations and comorbidities.1 6
Para sports aim to promote sports for people with disabilities. Non-disabled sports are modified to create a more inclusive and level playing field for people with different disabilities. No specific classification acts as an exclusionary criterion at the recreational level for most adapted sports programmes. However, to be eligible to compete in Para sports at International Competitions under the jurisdiction of an International Sports Federation, an athlete with an impairment must undergo an athlete evaluation to be classified. During this athlete evaluation, it will be determined whether the impairment (in this case, amputation) meets the minimum impairment criteria of that sport, which is the minimum level of impairment required to participate in the sport.7 For example, among the 28 Paralympic sports, only 10 have an eligible classification for persons with partial foot amputation: Para archery, Para athletics, Para badminton, Para cycling, Para rowing, Para swimming, Para table tennis, Para taekwondo, sitting volleyball and wheelchair tennis (table 1).8 The other 18 sports require either a more proximal level of lower limb amputation or a different impairment (eg, Para judo requires a visual impairment) to be eligible to participate.
This scoping review focuses on minimum impairment criteria in the Para sport of wheelchair tennis. Wheelchair tennis is a popular Para sport version of non-disabled tennis, and people with a partial foot amputation are eligible to compete. In 2021, the minimum impairment criteria for lower limb deficiency in wheelchair tennis were defined as ‘complete unilateral amputation of half the length of the foot (ie, measured on the non-amputated foot from the tip of the great toe to the posterior aspect of the calcaneus) or equivalent minimum congenital limb deficiency’.9 These minimum impairment criteria were adopted from Para athletics, and whether they were set at the correct level as an entry criterion for participating in wheelchair tennis has never been examined. Therefore, the International Tennis Federation (ITF) tasked an Expert Group to review the minimum impairment criteria for the Open Class of wheelchair tennis.
When developing evidence-based classification systems, the International Paralympic Committee (IPC) recommended that sports and researchers10:
specify the sport (class) and the eligible impairment types;
Develop valid measures of impairment.
Develop standardised and valid sport-specific measures of performance.
Assess the strength of associations between the measures of impairment and performance.
Develop minimum impairment criteria and class profiles for the sport.
Following the IPC research steps, the ITF Expert Group aimed to assess the strength of the association between different levels of partial foot amputation and non-disabled tennis performance. Ideally, one would review all studies of tennis players with partial foot amputation playing standing tennis and determine the association between amputation type and mobility on the tennis court. However, such studies were not available, whereas studies of the association between the types of partial foot amputation and walking gait were. Gait is the outcome parameter most likely to affect mobility on the tennis court. It was hypothesised that the more proximal and more extensive the amputation, the more substantial the functional limitation and, hence the motivation to undertake this review. Scoping reviews are ideal for determining the scope of the body of literature on a given topic, determining knowledge gaps and providing an overview of the subject matter. Because of the scant literature on partial foot amputation and gait, a scoping review is more appropriate for this topic than a systematic review.11 Therefore, this scoping review aimed to describe how different levels and types of partial foot amputation affect gait with a view to applying the findings to inform the development of minimal impairment criteria for wheelchair tennis.
This scoping review was based on the sixstep methodological framework developed for scoping reviews.12 13 The searching and selection processes followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis extension for scoping reviews (PRISMA-ScR) and aligned with the scoping review methodological framework.13 The protocol of this scoping review was previously registered at the Open Science Framework Registry (https://osf.io/8gh9y) and published.14
Literature search and study selection
A comprehensive search strategy in PubMed, Embase, CINAHL and SPORTDiscus (via Ebsco) from inception to 1 February 2021 was developed by one reviewer (FCLO) in collaboration with a medical librarian (LS). Database searches were then carried out by two reviewers (BMP, MGTJ). Search terms included controlled terms (MeSH in PubMed and Emtree in Embase, CINAHL Headings in CINAHL and thesaurus terms in SportDiscus) and free-text terms. An updated search was carried out on 9 February 2022, which did not provide additional records. The following terms (including synonyms and closely related words) were used as index terms or free-text words: ‘amputation’ and ‘forefoot’ or ‘midfoot’ and ‘gait’. These terms were determined using the Population, Interest/Exposure, Comparison, Outcome, and Study design approach. The search was performed without date, geographical location, gender, sex or language restrictions. The search strategies for all databases are available in online supplemental file 1.
Before screening the search results, duplicate articles were identified and removed using Endnote X V.19.2 (Clarivate, USA). The search yield was imported into Rayyan software,15 and two independent reviewers (FCLO and SW) screened the titles and abstracts for potentially eligible studies. Where there was any disagreement over inclusion, a consensus was reached through discussion with a third reviewer (BMP). Full-text versions were downloaded for all articles that appeared to meet the study inclusion criteria based on their titles and abstracts and reviewed to confirm eligibility. The reference lists of the selected studies were manually screened to identify additional relevant articles that may have been missed in the primary searches.
Inclusion and exclusion criteria
Included studies must have reported or analysed data from gait-related outcomes in individuals who underwent a partial foot amputation. The inclusion/exclusion criteria used to determine the eligibility of the included articles are available in online supplemental file 2. Reasons for exclusion are reported in the PRISMA flowchart in figure 1.16
Data extraction and synthesis
Data synthesis was performed qualitatively and quantitatively for all analysed outcomes to build a solid theoretical framework of the types of amputation associated with substantial abnormalities in gait parameters. A meta-analysis was not planned due to incomplete reporting of outcomes (ie, means, measures of spread, sample size) and clinical and methodological diversity in the evidence.17 Therefore, we decided to use a structured reporting of effects18 and calculated the mean difference (MD) with 95% CIs between patients with an amputation and the corresponding control group. We quantitatively analysed the variables gait speed in metres per second (m/s), step length in centimetres (cm), cadence in steps per minute (steps/min), stance time in seconds (s), peak plantar pressure in kilopascal (kPa) and ankle power in watts per kilogram (W/kg) and per kilogram-metre (W/kg-m). The 95% CIs were calculated assuming a t-distribution. The results were reported from the distal to proximal level of amputation.
The following data were extracted from the included articles: first author, year of publication, country involved, study design, aims of the study, study population (type of amputation, reason for amputation), mean age, control group, sample size and sex. For the study design, we followed the definitions of a case-control and cross-sectional study proposed by Dillon et al.19 If the same patients were included in two or more publications, these publications were considered as one study for this review.
The following data related to the outcome measures were extracted from the articles: assessment methods, gait-related outcomes without a prosthesis (spatiotemporal parameters, centre of pressure (CoP), ground reaction force (GRF), kinetics, kinematics), comparison, key findings related to the outcomes of interest, study limitations and conclusions.
In the case of a study providing only a median, IQR, and/or range, we transformed the values with an online tool that applied the quantile estimation method of McGrath et al.20 Where data were presented in a figure only, GetData Graph Digitizer21 was used to extract the values by measuring the length of the axes in pixels followed by the length of the relevant data of interest.22
Results are presented in summary tables, and quantitative results are displayed with forest plots. The results are reported from distal to proximal level of amputation.
Methodological quality assessment
Two independent reviewers (FCLO and BMP) assessed the methodological quality of all included studies using the Joanna Briggs Institute checklist for case reports (two studies) and analytical cross-sectional studies.23 24 The checklist for case reports consisted of eight items, including questions on the demographic characteristics, the patient’s history, clinical condition, diagnostic tests, intervention, postintervention clinical condition, adverse events and take-away lessons (online supplemental file 3). The checklist for analytical cross-sectional studies also consisted of eight items, including questions on study inclusion criteria, participants and setting, exposure, the condition, confounding factors (two items), validity and reliability of the measurement technique and statistical analysis (online supplemental file 4). Each question was rated as ‘yes’, ‘no’, ‘unclear’ or ‘not applicable’. The reviewers discussed differences until they reached a consensus. The quality assessment outcome was not used to determine study inclusion or perform subgroup analysis based on methodological quality or risk of bias and was performed post hoc.
Levels of evidence and grades of recommendation for the minimum impairment criteria were rated according to the Oxford Centre of Evidence-Based Medicine.25
A total of 1083 articles were retrieved from the electronic databases. Four additional articles were identified from the reference lists of the included studies. After removing 423 duplicates and screening the titles and abstracts of the 664 remaining records, 35 studies were selected for full-text analysis. Six additional studies were excluded, and the reasons for exclusion are presented in a flowchart (figure 1). Three research groups included the same patients in two,26 27 two28 29 and three30–32 different publications. Therefore, 29 publications of 25 studies met the inclusion criteria for this scoping review.
Characteristics of the included studies
The characteristics of the included studies are presented in table 2. Most study designs were either cross-sectional (n=14) or case–control (n=6), with two case reports33 34 and three pre–post studies.35–37
The included studies comprised 448 participants, 257 of whom had a partial foot amputation, and 191 were controls or had a more proximal amputation. The mean number of participants with partial foot amputation per study was 10 (ranging from 1 to 30). Most studies included adults (n=23) and two included children.36 38 The mean age of the adult participants with partial foot amputation ranged from 26 to 75.5 years, and 77.5% were men. Four studies did not report age,34 37 39 40 and seven did not report sex.19 30 32 36 39–43
Methodological quality assessment
Quality assessment of the included studies is presented in online supplemental files 3 and 4. The assessment methods were not clearly described in one of the two case studies, but all other items in both studies scored a ‘yes’. Most of the 27 analytical cross-sectional studies assessed clearly described the criteria for inclusion (item 1; 22/27, 81%), the study subjects and setting (item 2; 25/27, 93%) and measured the outcomes in a valid and reliable way (item 7; 22/27, 81%). All analytical cross-sectional studies measured the exposure validly and reliably (item 3; 27/27, 100%) and used objective and standard criteria for measuring the condition (item 4; 27/27, 100%). Only 15 out of 27 (56%) studies adequately identified the confounding variables (item 5), and only 7/27 (26%) reported the strategies used to manage them (item 6). Most studies (15/21, 71%) used appropriate statistical analyses (item 8); in 6 cases, this item was not applicable.
Amputation levels and types
Amputation types included were the great toe (n=6), other toes (n=3), metatarsophalangeal (MTP) joint (n=2), ray (n=3), transmetatarsal (TMT) (n=14), Lisfranc (n=2) and Chopart (n=3) (figure 2). Three studies30–32 36 44 analysed a mixed group of partial foot amputees. Kanade et al 44 included participants with great toe, other toes, ray, and TMT amputation but did not report them separately. Therefore, this publication is not discussed in the various subsections addressing the association between gait and different foot amputation types. Dillon and Barker30–32 and Greene and Cary36 reported gait-related outcomes specific to amputation types, and those data are discussed.
Reasons for amputation
Reasons for amputation included diabetes (n=10),26–29 39 41 44–49 finger or thumb reconstruction (n=5),33 37 38 40 50 trauma (n=4),30–32 51–53 peripheral vascular disease (n=3),39 42 43 tumour (n=1),54 rheumatoid arthritis (n=1),35 congenital and childhood-acquired amputation (n=1)36 and frostbite (n=1).34
The complete list of outcomes, key findings of the included studies and descriptive synthesis of the results are presented in table 3 and online supplemental file 5. The most often studied gait-related outcome measure was gait speed, examined in 15 studies included in this review.26–29 32 34 36–38 42 44–46 48 50 52 53 Other outcome measures addressed in the studies included cadence (n=9),32 37 38 42 45 46 50 52 53 step length (n=8),28 34 37 40 45 50 52 53 single and/or double limb stance times (n=5),32 34 37 45 53 stride length (n=6),32 37 38 42 46 52 step width (n=2),37 45 CoP (n=6),30–33 38 43 50 51 peak plantar pressure (n=6),26 28 44 47–49 51 ankle power (n=5),28 31 46 52 53 walking distance (n=1)35 and ambulatory function (n=1).39
The MD in gait speed between individuals with an amputation, and the corresponding control groups, is presented as a forest plot in online supplemental file 6. Data from some studies are missing because they lacked a control group29 36 38 50 or reported percentages only.32 42 Two studies34 52 compared individuals with amputations walking barefoot to walking with footwear, prosthesis or both. Two studies26 28 48 compared diabetic patients with non-diabetic controls. The remainder of the studies used appropriate control groups: diabetic patients for amputees with diabetes,44 45 non-amputees with peripheral vascular diseases for amputees with peripheral vascular diseases42 and non-diabetic persons for non-diabetic amputees due to trauma.32 53
Cadence, ankle power, step length, stance time and peak plantar pressure
MDs in cadence, ankle power, step length, stance time and peak plantar pressures between the affected and non-affected foot or between the group of patients with an amputation and a control group are presented as forest plots in online supplemental files 7–12.
Great toe amputation
The association between great toe amputation and gait was addressed in five publications.37 40 49–51 The sample size ranged from 4 to 12 patients per study. Duration of follow-up ranged from 6 months to 10 years. Outcome measures were spatiotemporal parameters, joint ROM, CoP excursion and plantar pressures during gait.
Amputation of the great toe was related to morphological abnormalities of the foot, including varus drift (8°) of the second metatarsal, retraction of the sesamoids, a decrease in the height of the medial longitudinal arc and descent of the first metatarsal head.40 Great toe amputation was associated with instability on the medial side of the foot, with the line of progression of the CoP more laterally and a decrease in forward progression.37 50 51 Gait speed was only minimally affected, but forward and lateral push-off was reduced.37 40
Toe amputation (digits 2 to 5)
Toe amputation other than the great toe was addressed in three publications: one concerning the second toe,38 one concerning one or more amputated toes46 and one concerning the second, third and fourth toes.33 Sample size ranged from 1 to 11. Amputation of the second toe may lead to claw foot, hallux valgus and a narrower foot and postural instability during single-leg stance with eyes closed, with gait kinematics remaining within normal values in two studies.33 38 Burnfield et al 46 reported significantly reduced gait parameters (gait speed, cadence and stride length) in seven patients with toe amputations secondary to diabetes compared with healthy controls.
The effect of ray amputation on gait was addressed in three publications.36 45 54 Aprile et al 45 compared six patients with ray amputation and type 2 diabetes to six patients with type 2 diabetes without amputation and six healthy subjects. The patients with diabetes and ray amputation walked slower and with more hip flexion. In addition, they had greater variability in lower extremity ROM and less ROM for the ankle, knee and hip compared with the patients with diabetes without amputation and the healthy controls. The authors concluded that the abnormal gait biomechanics might be caused by the severity of diabetes and the lack of a push-off phase from the great toe. Ramseier et al 54 studied foot function in four patients after ray resection for a malignant tumour, with a follow-up between 21 months and 8 years. Foot function analysed with pedobarography was nearly normal, with a slightly laterally displaced CoP. Greene and Cary36 included children with ray amputation in their study but did not report on this group separately, making it difficult to review their results.
Forczek et al 34 reported on a 30-year-old alpinist, 1.5 years after bilateral MTP amputation due to frostbite injury. Analysis of spatiotemporal parameters showed that the patient had a slower gait speed, shorter steps and decreased step frequency when walking barefoot than when wearing shoes. The authors concluded that this was related to reduced stability and lower confidence due to partial toe amputation when walking barefoot, as footwear provided more stable conditions.
Dillon and Barker30–32 studied seven amputees with mixed amputation levels (one MTP, one TMT, three Lisfranc and two Chopart) and compared their gait to the mean gait parameters and 95% CI of seven32 and eight30 healthy controls.
People with bilateral MTP amputation had a peak ankle power similar to that reported at the lower end of the 95% CI of the control sample. This was in sharp contrast to the patients in whom the metatarsal heads were amputated, as the generation of work across the ankle of the amputated limb was virtually negligible.30 The CoP progressed relatively normally along the length of the operated foot during the initial part of the stance phase.31 However, after loading, the CoP did not move as far distally along the foot length as usually observed in people without amputation. The GRF peak was consistent, and the magnitude was comparable to the lower limits of the control population.32
In people with TMT amputation, the metatarsal heads are amputated, resulting in the absence of the forefoot and a shortened foot and reduced foot lever. TMT amputation was addressed in 13 studies.26–32 35 36 39 41–43 46–48 53 The sample size ranged from 5 to 27 patients with TMT amputation, and the follow-up duration ranged from 6 months to 13.7 years. Outcome measures addressed in these studies were spatiotemporal parameters, GRF, CoP excursion, plantar pressures during gait, ROM and power generation. It is unclear whether the five patients from the two studies by Pinzur et al 42 43 were the same because their ages were reported in only one study.
In patients with TMT amputation, power generation across the ankle joint was virtually negligible (0.72 W/kg; compared with the normal cohort: 95% CI (2.56 to 5.06 W/kg)), regardless of the residual foot length.30 According to the authors, this was due to the diminished ankle moment coupled with joint angular velocity reductions.
This diminished ankle moment was also found by Garbalosa et al,47 with the authors reporting that feet with TMT amputation have a significantly decreased heel and increased forefoot peak plantar pressure compared with the intact foot. A considerably decreased maximum dynamic dorsiflexion ROM (70% vs 90%) and a similar static ROM were measured in the ankles of the amputated feet compared with the ankles of the intact feet.
In TMT amputees, reductions in work across the affected ankles were compensated for by increased power generation at the hip joint.30 They appeared to rely more heavily on advancing their leg using the hip flexor muscles rather than the plantar flexor muscles, which had a shortened lever arm.27 Hip extension strength was highly correlated with gait speed, functional reach and physical performance score.29
Dillon and Barker31 showed that the CoP did not continue to progress distally along the length of the residuum but remained well behind the distal end throughout most of the stance phase until double limb support. Wearing a prosthesis can improve the situation somewhat but does not resolve it. Tang et al 53 found ankle moments in the terminal stance of TMT amputation when walking barefoot was only 45% relative to the control group. This improved to 62% when wearing a prosthesis. Ankle power generation in the preswing phase was only 28% compared with the control group, improving to 31% after wearing the TMT amputation prosthesis.
People with a TMT amputation walk slower and generate lower plantar flexor ankle moments and power than age-matched controls.26 27 48 In these studies, persons with diabetes and TMT amputation were compared with healthy controls. There have been no studies comparing healthy people with a TMT amputation to a healthy population without amputation or studies comparing people with diabetes with and without TMT amputation.
Lisfranc and Chopart amputation
Chopart amputation was addressed in three studies, one with four Chopart amputee patients52 and two mixed with other amputation types,30–32 36 resulting in a total of 11 patients with a Chopart amputation. Lisfranc amputation was reported in two studies, both mixed with other amputation levels, with a total of six patients with a Lisfranc amputation.
Greene and Cary36 studied children with traumatic or congenital amputation and showed that patients with an MT, ray or TMT amputation had superior results over those with a Syme amputation. Patients with a Lisfranc or Chopart amputation had better overall function than those with a Syme amputation but needed to make greater adjustments to their gait. Patients with a Chopart amputation and equinus contracture had inferior results compared with patients with a Syme amputation.
Burger et al 52 reported on four patients who underwent Chopart amputation due to trauma (mean age 42.3±17.2 years) and had a reduced gait speed (0.89±0.19 m/s) compared with the norm (≈1.40 m/s for age 60–65 years).55 Gait speed improved when wearing a silicone prosthesis (1.18±0.2 m/s) and when wearing footwear with a standard (0.99±0.22 m/s) or silicone prosthesis (1.16±0.24 m/s), but it was never normalised.
Dillon and Barker32 showed that in patients with Chopart amputation, power generation across the ankle was negligible, comparable to patients with TMT amputation. The hip joints were the primary source of power generation. The use of a clamshell prosthesis restored their effective foot length and normalised many aspects of their gait but did not restore ankle power generation.
This scoping review described how different levels of partial foot amputation affect gait. The main findings were that partial foot amputations were associated with various gait changes, depending on the type of amputation. Toe amputations were associated with minor gait abnormalities, and great toe amputations caused loss of push-off in a forward and lateral direction. MTP amputations were associated with loss of stability and decreased gait speed. Ray amputations were associated with decreased gait speed and reduced lower extremity range of motion (ROM). TMT amputations and more proximal amputations were associated with abnormal gait, substantial loss of power generation across the ankle and impaired mobility. These findings are discussed below from distal to proximal level of amputation.
As shown in the forest plots, great toe, TMT, Lisfranc and Chopart amputations were associated with significant loss of gait speed, but some studies lacked a proper control group. Cadence and stance times were measured in only a few small studies, and 95% CI could not be calculated, making it difficult to draw firm conclusions. The other studies showed no significant difference. The forest plot of peak plantar pressure and step length showed a wide 95% CI, which also precludes drawing valid conclusions. Step length was significantly reduced in patients with first ray amputation compared with a proper control group, but this study examined only six patients. The forest plots showed that ankle power was significantly reduced in TMT patients.
Great toe amputation
Toe amputation is the most common lower extremity amputation. In 2017, the incidence ranged from 78 per 100 000 men (43 per 100 000 women) in Australia to 31.3 per 100 000 men (20.1 per 100 000 women) in the Netherlands.56 Based on this scoping review of the literature, amputation of the great toe did not lead to significant changes in gait, including gait speed, cadence, step length, step width or the single and double limb stance times of each foot. However, great toe amputation can lead to medial instability of the foot, as shown by a decrease in the height of the medial longitudinal arch, a descent of the first metatarsal head and sesamoid retraction, due to loss of the windlass mechanism of the plantar aponeurosis.50 It is also associated with loss of weight-bearing of the great toe and lateralisation of the CoP under the second and third metatarsal and varus drift in the second metatarsal joint. Thus, great toe amputation was associated with loss of power on pushing off and lateral movements.40
Ray amputation involves excision of the toe and part of the metatarsal. Aprile et al 45 found abnormal gait biomechanics in patients with type 2 diabetes and ray amputation compared with patients with type 2 diabetes without amputation or healthy subjects. Ray amputations were associated with a lower gait speed, a higher degree of hip flexion, greater variability in lower extremity ROM and less ankle, knee and hip ROM. The abnormal gait biomechanics may be caused by the severity of diabetes and the lack of a push-off phase from the great toe. In addition, neuropathy affects 50% of patients with diabetes and amputation, but only one in six patients with diabetes. Aprile et al 45 concluded that these findings suggest that the abnormal gait performance may be due to the missing first ray and more severe neuropathic pain.
Harlow et al 57 reported on a collegiate athlete with second ray amputation due to heterotopic ossification in the first web space. A year later, a right great toe cheilectomy was performed. Four years later, she was unable to return to competitive soccer but could participate in exercise walking and low-impact athletic activities.
Few studies have reported on ray amputation and gait, making it difficult to draw firm conclusions. However, based on the current evidence, it is likely that ray amputation, particularly first ray amputation, has a significant effect on lower extremity function during gait.
MTP amputation or disarticulation is an amputation of the toes that leaves the metatarsal heads in place. This amputation is not very common because surgeons generally prefer to perform a partial toe amputation or to include the metatarsal head in order to have enough skin tissue to cover the amputation stump. We found only two studies with this amputation, and each only included one patient. Unlike TMT amputation, after MTP amputation, power generation across the ankle stayed within the lower end of the 95% CI of the control sample.30
Amputation proximal to the MTP joints, including the metatarsal heads, is associated with a substantial reduction in power generation across the ankle, which is compensated by increased power generation across the hip joints and significantly reduced CoP excursions. A TMT amputation is associated with reduced ankle plantar flexor moments, with peak plantar flexor moments two-thirds of those measured in the control group.28 32 53 The inability to generate enough power across the ankle was caused by a reduction in the capacity of the calf muscles to plantarflex the ankles and generate the necessary ankle torque to move the amputated foot. Limited distal progression of the CoP and a shorter foot lever of the amputated limb appear to contribute to the altered moments and power profiles in TMT amputation.19 32
The CoP remained proximal to the distal end of the amputated foot until after the contralateral heel contact with the ground. When there is double support, the CoP moves to the distal end of the amputated foot, and then the centre of mass shifts to the intact limb. In this situation, the lever arm of the GRF is longer, and the extent of the vertical GRF decreases, so that the plantar flexion moment diminishes.32
Increased power generation across both hip joints provides the additional work necessary to move the body forward and compensate for reduced power generation across the affected ankle. The increase in work across the intact hip joint during early stance provides the forward impulse for the pelvis, and the increased power generation across the amputated side during early stance helps to move the body forward from the rear.19
Substantial reductions in gait speed and stride length were reported in several studies of patients with TMT amputations.26–28 48 In all of these studies, the patients with TMT amputation had diabetes and were compared with healthy participants without diabetes or amputation. No studies compared the gait speed of patients with TMT amputation without diabetes to healthy controls without amputation, making it difficult to separate the effect of amputation from the effect of diabetes.
Lisfranc and Chopart amputation
Lisfranc and Chopart amputations are associated with a similar loss of power generation across the ankle due to the TMT amputation, with the accompanying abnormalities in gait parameters. Therefore, individuals with these proximal partial foot amputations may experience a substantial loss of function in their lower extremities, and their mobility will be significantly affected.
Potential implications for minimum impairment criteria in wheelchair tennis
This scoping review provides a consolidated overview of the gait pattern impairments associated with different levels of partial foot amputation. Descriptions of gait pattern impairments will guide the development of minimum impairment criteria for lower limb deficiency in the sport of wheelchair tennis. After great toe amputation, players may be disadvantaged when participating in standing tennis against non-disabled athletes, as the game requires frequent direction changes, sideways movements and forceful pushing off. On average, tennis players hit five strokes per rally58 59 and change directions five times,60 amounting to approximately 400 changes of direction in a best-of-three-set match.61 More than 70% of movements in tennis are sideways; on average, a player covers 2 m per lateral movement.62 In addition, the great toe is needed for the push-off during serving.63 Ray amputations are associated with abnormal gait biomechanics and reduced gait speed. People with first ray amputations lack the push-off phase from the great toe. It is likely that ray amputation, particularly first ray amputation, will affect sprinting, jumping, turning and mobility performance in tennis. TMT amputation is associated with substantial functional limitations of the lower extremities due to the loss of power generation across the ankle. Due to loss of power generation, the athlete may have reduced acceleration and deceleration, reducing their level of mobility in sport. Tennis requires frequent acceleration and deceleration over an extended period. Tennis matches (best-of-three-sets) last around 1 hour and a half.64 65 Players cover 8 m to 10 m per point and 550 m to 700 m per set,66 67 with a peak running speed of 20 km/hour in elite male and 17 km/hour in elite female players.59 68–70 During a best-of-three-set tennis match, an elite tennis player accelerates more than 150 times with an acceleration speed of over 3 m/s2.71 It is unlikely that a player with a TMT amputation could produce the power necessary to match these physical demands. Mobility will likely be less affected in people with an MTP amputation than in people with a TMT amputation, but it is difficult to draw firm conclusions regarding the effect on mobility performance in sports based on the limited data. We expect that the effect of Lisfranc and Chopart amputations on tennis mobility is similar to that of a TMT amputation, but further studies in healthy individuals with these types of amputations are needed.
Minimum impairment criteria state the minimum level of impairment required to participate in the sport (ie, wheelchair tennis). Factors that need to be considered to develop minimum impairment criteria are the extent to which the impairment (ie, amputation) affects the ability of the player to execute the specific tasks and activities fundamental to non-disabled tennis and the strength of the evidence.72–74 Fundamental activities of non-disabled tennis include accelerations, decelerations, changes of direction, lateral movements, running and jumping. The minimum impairment criteria should be conservative enough to protect the integrity of the Para sport wheelchair tennis, but not so conservative that it excludes people with significant disadvantages in tennis. Based on the results of this scoping review, we recommend excluding toe amputations and including first ray, TMT, Chopart and Lisfranc amputations in the minimum impairment criteria for wheelchair tennis (table 4). It is unclear whether great toe, ray and MTP amputations should be included or excluded. This should be discussed further in an expert group, and more research is recommended.
Strengths and limitations
The strengths of this scoping review are the systematic search and quantitative and qualitative data synthesis of all analysed outcomes, providing a comprehensive overview of the literature on partial foot amputation and gait. We identified 25 studies evaluating gait-related outcomes in patients who had undergone different types of partial foot amputation, allowing us to describe how different levels of partial foot amputation affect gait. However, 17 out of 25 studies were published more than 20 years ago, and the most recent study was published in 2018. This may have impacted the findings because surgical techniques may have improved over the years, surgical indications may have changed, and technology has advanced.
Our review was also limited by the small and heterogeneous populations in most studies. Amputee cohorts were diverse, including follow-up periods since amputation, amputation level and involvement of the contralateral limb. Few studies drew comparisons between participants with amputation and a suitably matched control group. Eleven out of 25 studies included participants with amputation due to diabetes, and in 9 out of 25 studies, the mean age of the participants was 58 years or older, making it difficult to extrapolate the findings to the athletic population.
Partial foot amputations were associated with various gait changes, depending on the type of amputation. Different levels and types of foot amputation are likely to affect tennis performance and should be considered when determining minimum impairment criteria for wheelchair tennis. We recommend studying gait and sporting performance in a large cohort of healthy, younger patients with similar partial foot amputation types and an adequately matched control group. However, since partial foot amputations in younger populations are relatively rare, and the most common causes are trauma, tumours and congenital anomalies, it may be difficult to get sufficiently large study groups with similar amputation types. Therefore, this would require multicentric studies.
Patient consent for publication
We thank Dr Mohd Sameer Qureshi, MBBS, DNB Orthopaedics, for creating the illustrations.
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Contributors FCLO, SW, CLA and BMP contributed to the conception and study design. LS contributed to the search strategy. FCLO, SW and BMP conducted the data extraction, analysis and interpretation. TS performed the statistical analysis. FCLO, NH, CJvR, SW and BMP drafted the manuscript. All authors contributed to the manuscript with critical reviews and approved the final version of this paper.
Funding All authors thank the International Tennis Federation and the Royal Dutch Lawn Tennis Association (KNLTB) for supporting this research. We thank Dr Mohd Sameer Qureshi, MBBS, DNB Orthopaedics, for creating the illustrations.
Competing interests CA is Editor-in-Chief for JOSPT and JST is Editor for BJSM. At the time of writing, BMP was a classification consultant for the ITF, tasked to review the ITF minimum impairment criteria, and Chair of the ITF Classification Working Group.
Provenance and peer review Not commissioned; externally peer reviewed.
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