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Gait in prosthetic rehabilitation

Original Editor - Abby Cain as part of the World Physiotherapy Network for Amputee Rehabilitation Project

Top Contributors - Admin, Rachael Lowe, Jess Bell, Kim Jackson, Tarina van der Stockt, Naomi O'Reilly, Ewa Jaraczewska and Simisola Ajeyalemi  

Normal Gait

Gait describes a person's walking pattern, with ‘normal gait’ acting as a baseline reference averaged across a population, factoring in variables such as age and sex.[1] A single gait cycle encompasses all phases of movement, from the initial contact of one foot to the subsequent initial contact of that same foot. When discussing gait, it is important to distinguish a stride from a step: a stride refers to the full gait cycle, whereas a step is the interval from the initial contact of one foot to the initial contact of the opposite foot.[2]

Step and stride in human gait


The gait cycle is divided into two primary phases:[3]

  1. Stance phase: The period when the foot is in contact with the ground. This includes weight acceptance and single-leg stance (i.e. the "heel-to-toe contact sequence of the foot"[4]). This makes up approximately 60% of the cycle.[1]
  2. Swing phase: The period where the limb is lifted from the ground for limb advancement (i.e. when the foot is suspended[4]). This makes up approximately 40% of the cycle.[1]

The gait cycle can be further broken down into eight distinct phases:[1][2][5]

  • Initial contact
  • Loading response
  • Midstance
  • Terminal stance
  • Preswing
  • Initial swing
  • Midswing
  • Terminal swing
Phases of the gait cycle

Initial Contact

Initial contact is also known as heel strike. It is the moment the foot comes into contact with the ground, and it aims to stabilise the limb in preparation for weight transfer. The hip is flexed to approximately 20-30 degrees, the knee is extended between 0-5 degrees, and the ankle is in a neutral position held by the dorsiflexors. This marks the first phase of double-limb support.[2][6]

Loading Response

Loading response begins with initial contact and continues until the opposite foot leaves the ground. The foot lowers to a flat position through controlled ankle plantar flexion, with the dorsiflexors contracting eccentrically to absorb shock as the heel acts as a 'rocker'. The subtalar joint rolls into pronation, providing further shock absorption. The hip begins to extend, and forward momentum propels the body over the foot. The knee then flexes to approximately 15 degrees of flexion to absorb shock. The goals of this phase are shock absorption, weight-bearing stability and the preservation of forward progression.[2][6]

Midstance

Midstance begins when the opposite foot leaves the ground. It is the first half of single-limb support. Weight is fully aligned over the supporting foot through gradual ankle dorsiflexion, while the hip and knee extend. The body weight is fully supported on one leg.[2][6]

Terminal Stance

Terminal stance (also known as heel-off) is the second half of single-leg support. It begins as the heel of the loaded limb lifts off the ground and continues until the contralateral foot contacts the ground. The body then moves forward past the forefoot as the hip further extends. The knee reaches near full extension before beginning to flex again.[2][6]

Preswing

Preswing (also known as ‘toe-off') is the final phase of stance. It begins when the opposite foot contacts the ground and ends when the stance foot leaves the ground. The limb is rapidly offloaded as the knee flexes and the ankle plantarflexes. Preswing provides the final burst of propulsion as the toes leave the ground.[2][6]

Initial Swing

Initial swing (also known as early swing) begins when the foot leaves the ground and ends when it is level with the opposite ankle. The foot is lifted off the floor via hip and knee flexion, as the ankle begins to dorsiflex. The opposite foot is in the midstance phase.[2][6]

Midswing

Midswing begins from ankle-foot alignment and continues until the tibia of the swing leg is vertical. The limb swings forward of the body through continued hip flexion as the knee begins to extend. The ankle remains in a neutral position to ensure the foot clears the ground.[2]

Terminal Swing

Terminal swing (also known as late swing) begins when the tibia of the swing leg is vertical and ends with initial contact. The knee becomes fully extended, and the ankle maintains its neutral position to prepare for heel strike.[2]


[7]

Prosthetic Gait

Individuals with lower-limb amputations use different muscle groups to achieve a smoother gait pattern. Overall energy consumption also increases. While prosthetic design has advanced considerably, "the replacement of lower-limb segments with a prosthesis affects the efficiency of this locomotion."[8] In people without amputation, the rate of metabolic oxygen consumption rises with walking speed. However, the metabolic cost is higher in people with lower-limb amputations, even at comfortable walking speeds. Increased demands vary depending on amputation level and aetiology:[9]

  • Traumatic transtibial gait - 25% increased energy requirement
  • Vascular transtibial gait - 40% increased energy requirement
  • Traumatic transfemoral gait - 68% increased energy requirement
  • Vascular transfemoral gait - 100% increased energy requirement

Transtibial Gait

While the average gait pattern varies depending on the type of prosthesis used for mobility, several generalisations can be made.

The ankle of the prosthesis has a reduced range of movement compared to an anatomical ankle joint. This results in prolonged heel strike and weight bearing through the heel before flat foot contact, with delayed forefoot loading.[10]

Knee flexion is decreased at initial contact, and the overall maximum flexion achieved is reduced as the foot moves to floor contact.[10] During the swing phase of the non-prosthetic limb (intact side), the body weight begins to move forward over the prosthetic limb, which is in the stance phase. To achieve adequate step length with the non-prosthetic limb, early and increased heel rise occurs on the prosthesis.[10] This elevates the body and increases the loading force on the non-prosthetic side. Consequently, a greater quadriceps contraction is required on the intact side to absorb this impact force.[9][10]

Additionally, the terminal stance ‘toe off’ force generated from the prosthetic limb is reduced, which is compensated for by the hip flexors. Flexion of the knee on the prosthetic limb occurs with some hamstring contraction but mainly eccentric contraction of the quadriceps.[11]

During stance phase, the prosthetic limb performs around half of the work of biological muscles;[12] proximal muscle energy expenditure increases to compensate for this. The rocker effect of the prosthesis increases instability, and reduced prosthetic knee flexion means the hip muscles must generate more energy to maintain stability.[9]

Due to limited prosthetic ankle mobility, hip extension range of motion on the prosthetic side is approximately half of that of the intact side. Stance time on the intact side is also longer than on the prosthetic side.[10]

Transfemoral Gait

A person with a transfemoral amputation must compensate for the loss of both the knee and ankle joint.[9] Their gait cycle is affected by the quality of the surgery, the type and alignment of the prosthesis, the condition of the residual limb, and the length of the remaining muscles and how well they were reattached.[11]

The main focus of the gait cycle is to prevent the knee from buckling during the stance phase. Prosthetic knees range from manually locking units to polycentric, hydraulic and microprocessor-controlled designs.[13] A useful distinction for gait is whether the knee stays locked in extension during stance or not. A locking ('fixed') knee prevents buckling mechanically. A non-locking ('free') knee relies on alignment and muscular control, and must remain in extension through much of the stance phase to ensure buckling does not occur.[13] This causes prolonged heel contact and the body moves forward over the prosthetic leg as one unit for the stance phase. The hip extensors on the prosthetic side help stabilise the limb during prosthetic weight-bearing.[9]

During the swing phase of the prosthetic limb, the hip extensors and calf muscles on the intact side help to generate force for the intact limb to swing forward. The hip flexors on the prosthetic limb must generate the same force required during normal gait. Although a prosthesis typically weighs less than half of a biological limb,[14] the hip flexors must generate enough speed to snap a non-locking ('free') knee prosthesis into extension for heel strike.[9][10]

Strength and control are reduced in a transfemoral amputation due to the shortened lever arm of the thigh muscles.[9]

For people fitted with a locking ('fixed') knee prosthesis, ground clearance is reduced during the swing phase due to the lack of knee flexion and ankle dorsiflexion. To prevent the foot from dragging on the floor, the person must elevate their pelvis using trunk and hip musculature, creating ‘hip hitching’ or ‘hip hiking.’[10]

Stance time on the non-prosthetic limb is increased due to prosthetic instability and reduced range of motion. Overall energy expenditure is higher than for people with transtibial amputations because energy is lost across two missing biological joints. This requires greater compensation from the hip and trunk muscles and the intact limb.[9]

On average, people with transfemoral amputations walk 30% slower than those without an amputation. The non-prosthetic limb experiences higher ground reaction forces, exaggerated joint moments, and an increased single-limb stance duration. This results in asymmetry that can lead to low back pain and osteoarthritis in the non-prosthetic limb.[15]

Gait Deviations

When assessing gait, it is important to know the parameters of a normal gait pattern and how they change in people with lower-limb amputations. Individual impairments causing gait deviations, such as muscle weakness or tightness, lack of balance, or fear, must be recognised and addressed in rehabilitation. [11][10]

[16]

If you would like to learn more about common gait deviations, see: Gait Deviations in Individuals with Lower Limb Amputations.

Conclusion

A full functional and physical assessment is required for all individuals with lower-limb amputations. This informs personalised goals and an individualised exercise programme. Understanding normal gait, common deviations and their causes helps guide this.[17][18] Numerous techniques can be used during rehabilitation, but not all will suit every individual, so the programme and technique should be tailored to the person and reviewed regularly.[10][17] A person's previous level of activity, overall health and potential to improve must also be considered, remembering the overall aim of translating gains made in a controlled environment into function in the person's home and community.[17][18]

References

  1. ↑ 1.0 1.1 1.2 1.3 Fish DJ and Nielsen CP. Clinical Assessment of Human Gait. Journal of Prosthetics and Orthotics 1993. 2(39).
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 Perry J and Burnfield J.M Gait Analysis, Normal and Pathological Function. 2nd Ed. USA, SLACK Incorporated USA 2010
  3. ↑ Masood H, Farooq H. Utilising spatio-temporal gait pattern and quadratic SVM for gait recognition. Electronics. 2022; 11(15):2386.
  4. ↑ 4.0 4.1 Cicirelli G, Impedovo D, Dentamaro V, Marani R, Pirlo G, D'Orazio TR. Human gait analysis in neurodegenerative diseases: a review. IEEE J Biomed Health Inform. 2022 Jan;26(1):229-42.
  5. ↑ Yan S-H, Liu Y-C, Li W, Zhang K. Gait phase detection by using a portable system and artificial neural network. Medicine in Novel Technology and Devices. 2021;12:100092.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Physiopedia. Gait Cycle http://www.physio-pedia.com/Gait_Cycle (accessed 5 February 2015)
  7. ↑ Global HELP Organization. Understanding & Analyzing Gait For The Clinician: Part 05 [The Gait Cycle] May 2018. Available from: https://youtu.be/96nLX6sm9Yw.
  8. ↑ Di Gregorio R, Vocenas L. Identification of gait-cycle phases for prosthesis control. Biomimetics (Basel). 2021 Mar 26;6(2):22.
  9. ↑ 9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7 Kishner's Gait Analysis after Amputation updated July 2013 http://emedicine.medscape.com/article/1237638-overview (accessed 3 February 2015)
  10. ↑ 10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 Smith D,, Michael J, W and Bowker J,H American Academy of Orthopaedic Surgeons. Atlas of Amputations and Limb Deficiencies. Surgical, prosthetic and rehabilitation Principles. 3rd Ed. USA. 2011
  11. ↑ 11.0 11.1 11.2 Australian Physiotherapists in Amputee Rehabilitation http://austpar.com (accessed 7 February 2015)
  12. ↑ Tacca JR, Colvin ZA, Grabowski AM. Greater than recommended stiffness and power setting of a stance-phase powered leg prosthesis can improve step-to-step transition work and effective foot length ratio during walking in people with transtibial amputation. Front Bioeng Biotechnol. 2024 Jul 1;12:1336520.
  13. ↑ 13.0 13.1 Liang W, Qian Z, Chen W, Song H, Cao Y, Wei G, Ren L, Wang K, Ren L. Mechanisms and component design of prosthetic knees: A review from a biomechanical function perspective. Front Bioeng Biotechnol. 2022 Sep 15;10:950110.
  14. ↑ Preatoni G, Valle G, Petrini FM, Raspopovic S. Lightening the perceived prosthesis weight with neural embodiment promoted by sensory feedback. Curr Biol. 2021 Mar 8;31(5):1065-1071.e4.
  15. ↑ Harandi VJ, Ackland DC, Haddara R, Lizama LE, Graf M, Galea MP, Lee PV. Gait compensatory mechanisms in unilateral transfemoral amputees. Medical Engineering & Physics. 2020 Jan 7.
  16. ↑ American Academy of Orthotists and Prosthetists. Prosthetic Observational Gait Scale (POGS). Dec 2017. Available from: https://youtu.be/Syv3vfwm2Js
  17. ↑ 17.0 17.1 17.2 Gailey R,S and Curtis R,C. Physical Therapy Management of Adult Lower-Limb Amputees. Atlas of Limb Prosthetics; Surgical Prosthetic and Rehabilitation Principles. Chapter 23. Abridged version. O and P Virtual Library
  18. ↑ 18.0 18.1 British Association of Chartered Physiotherapists in Amputee Rehabilitation. Evidence-Based Clinical Guidelines for the Physiotherapy Management of Adults with Lower-Limb Prostheses. CSP Clinical Guideline 03. November 2012
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