Amputee Gait Analysis & Training

Biomechanics of Transfemoral Amputee Gait

Many factors can determine the specific kinematics & kinetics of transfemoral amputee gait patterns, including:

  • Stump length & range
  • Type of prosthetic components: socket, knee, ankle, suspension
  • Alignment of the prosthesis
  • Quality of the amputation surgery
  • Condition of the intact limb
  • Other amputee-specific factors: age, cause of amputation, pain, confidence, etc

Most gait characteristics are compensations for the limitations of the prostheses available, and the loss of muscle mass and forces generated by the remaining hip musculature(7). The information on this page is general in nature, although there may be differences depending on the factors listed above, particularly the type of prosthetic knee joint. Many authors comment that comparison in gait parameters with different components may be limited due to the limited periods of acclimation to new components, which in some studies was as little as 10 minutes. Other authors suggest that many of the compensatory movements observed are performed as a result of the limitations of walking with a prosthesis, that asymmetries and compensations are adapted within the constraints of the residual musculoskeletal system and the prosthesis(34), with some authors even suggesting that these adaptations should not be trained out because of the purpose they serve in improving safety and stability. However, there is also plenty of proponents for attempting to normalise gait patterns as much as possible, which in turn could lead to better symmetry, energy-efficiency, and reduce the long term negative effects of prosthetic gait on the contralateral limb.

This page discusses the biomechanics of the amputation itself, and general characteristics of transfemoral gait, while Page 2 discusses each joint in more detail. For detailed discussion on the types of transfemoral prostheses, see our Prosthetics Portal.

Go directly to Page 2 --> Biomechanics at each specific joint.

  • Transfemoral
  • Temporal
  • Ground
    Reaction Forces
  • Metabolic
  • Transfemoral

Biomechanics of the Transfemoral Stump

The surgical technique can have a significant effect on the amputation stump, and can influence:

  • The ability to maintain the normal, adducted position of the femoral remnant within the prosthetic socket
  • The ability of the residual hip musculature to generate torque
  • The ability to maintain hip muscle length and avoid contractures

The medial portion of Adductor Magnus contributes 4-5 times the adduction moment the Adductor Brevis & Longus, due to its greater bulk, more distal attachment, and longer lever arm. Loss of the distal 1/3 of Adductor Magnus can lead to a 70% reduction in the moment arm (4). Therefore keeping this muscle intact and securely anchored contributes to maintaining the balance between adductors and abductors, and assists in maintaining the alignment of the femoral remnant, improving control over the prosthesis.

There are many muscles which can be affected by the amputation surgery, many of which were previously biarticular. During the surgery, there is the potential to incorrectly re-attach these muscles, leading to a significant mechanical disadvantage and atrophy (8). For example, Gluteus Maximus may have 3/4 of its insertion on the iliotibial band (ITB)(1). Failure to adequately anchor the ITB can cause retraction of the Gluteus Maximus, atrophy, and reduced ablity to generate tension(7). Similarly, in amputees where the ITB was not fixed the tensor fasciae latae showed a low level of activity throughout the entire stance, compared with a larger single peak in midstance(28).

Because of the nature of transfemoral amputation surgery, the hip flexors, abductors and external rotators can have a mechanical advantage over extensors, adductors and internal rotators. Muscles that are cleaved or affected during the surgery include Adductor Magnus (extensor & adductor), Hamstrings (extensor), Gracilis (internal rotator) and Gluteus Maximus (via ITB, an extensor). Muscles generally intact include Iliopsoas (flexor), Gluteus Medius & Minimus(abductor and external rotators) and the smaller hip external rotators. Incorrect reattachment of cleaved muscles places the flexors, abductors and external rotators at a mechanical advantage, and can increase the risk of contracture. This can be compounded by reattaching Rectus Femoris too tightly.

Thus it seems the muscles most important for prosthetic use are those likely to be most affected during the surgery, with quality of surgery influencing the risk of contracture, atrophy, and inability to generate torque.

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Temporal Characteristics

Comfortable walking speed can be 29% lower than controls, while fast walking speed can be 11% lower(7). This is usually due to a reduced cadence compared to normals(12). This reduced comfortable walking speed can actually be lower than the most metabolically efficient walking speed, so at times faster gait may be more energy efficient(6).

Amputees also generally change their walking speed by changing their stride length, rather than cadence(7). This may be due to the inability of most prosthetic knees to vary their swing phase times in response to changes in the amputee's walking velocity.

General characteristics include:(7, 11, 12, 23, 25, 32)

  • A longer prosthetic swing phase
  • A shorter intact limb swing phase
  • A shorter prosthetic stance phase
  • Reduced single support time on the prosthetic side
  • A longer intact limb stance phase
  • Increased stride widths (7-16cm up to 16-30cm)
  Controls Hydraulic Knees Constant Friction Knees
Intact Stance 56-60% 62% 66%
Intact Swing 40-44% 38% 34%
Prosthetic Stance 56-60%* 55% 45%
Prosthetic Swing 40-44%* 45% 55%

Gait symmetry does tend to improve with:

  • Increased walking speeds(7, 24)
  • Use of hydraulic or pneumatic knee joints(2, 12, 18) due to better swing phase damping during heel rise & terminal swing, leading to a faster swing phase.
  • Longer stump lengths(7, 24)

Gait symmetry can also improve with intense gait training(26).

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Ground Reaction Forces

Prosthetic limb loading, as measured by the vertical ground reaction forces, are decreased(18). Ground reaction forces are also less in the C-Leg compared to other knees such as the Mauch SNS, perhaps due to a smaller prosthetic step length with the C-Leg limiting the buildup of momentum.

Ground reaction forces are increased in the intact limb compared to controls. It is suggested that this is because of the lack of flexion damping of the prosthetic knee which causes excessive rise in the centre of mass over the prosthetic limb during midstance(13), increasing the force with which the intact limb strikes the ground. It could also be due to the faster swing phase of the intact limb (see Temporal Characteristics).

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Metabolic Cost

Metabolic cost has been found to be increased compared to normal, with figures quoted from a 27 to 88% increase(3, 15, 21). This may be due to:

  • Asymmetric gait patterns
  • Increased work of various muscle groups in the residual limb and intact limb
  • Excessive co-contraction
  • Abnormal trunk movements
  • Increased concentration
  • Absent sensorimotor control in the prosthetic limb

The increased energy cost can mainly be explained by an increased duration of activity of most hip muscles, required to control the passive prosthetic structures, and the need to transfer forces from the stump to the prosthesis(28).

The C-Leg is showing trends to reducing metabolic cost, although many studies are showing this is not significant(15). These authors suggest individual assessment may highlight whether the benefits are worth the cost to a particular amputee. They also note that alignment adjustments to the C-Leg are subjective, based on subject feedback and prosthetist observations, and the result may not be the most optimal pattern without scientific objectivity.

Other authors(9) are finding that variable damping knees such as the C-Leg or Rheo do reduce metabolic cost, with the Rheo reducing metabolic rate by 5% compared to the passive hydraulic in the Mauch SNS, and 3% compared to the C-Leg. The C-Leg reduced metabolic rate by 2% compared to the Mauch, but this was not significant.

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  1. Basmajian JV (1982). Primary Anatomy. 8th Edition, Williams & Wilkins, Baltimore.

  2. Boonstra AM, Schrama JM, Eisma WH, Hof AL, & Fidler V (1996). Gait analysis of transfemoral amputee patients using prostheses with two different knee joints. Archives of Physical Medicine & Rehabilitation, 77, May, 515-520.

  3. Gitter A, Czerniecki JM, & Weaver K (1995). A reassessment of center-of-mass dynamics as a determinate of metabolic inefficiency of above-knee amputee ambulation. American Journal of Physical Medicine & Rehabilitation, 74, 5, 332-38.

  4. Gottschalk FA & Stills M (1994). The biomechanics of trans-femoral amputation. Prosthetics & Orthotics International, 18, 12-17.

  5. Hale SA (1990). Analysis of the swing phase dynamics and muscular effort of the above-knee amputee for varying prosthetic shank loads. Prosthetics & Orthotics International, 14, 125-135.

  6. Jaegars SMJH, Vos LDW, Rispens P, & Hof AL (1993). The relationship between comfortable & most metabolically efficient walking speed in persons with unilateral above-knee amputation. Archives of Physical Medicine & Rehabilitation, 74, May, 521-525

  7. Jaegars SMJH, Arendzen JH, & de Jongh HJ (1995). Prosthetic gait of unilateral transfemoral amputees: a kinematic study. Archives of Physical Medicine & Rehabilitation, 76, 736-743.

  8. Jaegars SMHJ, Arendzen JH & de Jongh HJ (1995a). Changes in hip muscles after above-knee amputation. Clinical Orthopaedics & Related Research, 319, Oct, 276-284.

  9. Johansson JL, Sherrill DM, Riley PO, Bonato P, & Herr H (2005). A clinical comparison of variable-damping and mechanically passive prosthetic knee devices. American Joournal of Physical Medicine & Rehabilitation, 84, 8, 563-575.

  10. Kastner J, Nimmervoll R, Kristen H, & Wagner P (1999). What are the benefits of the C-Leg? A comparative gait analysis of the C-Leg, the 3R45 and the 3R80 prosthetic knee joints. Medizinisch Orthopädische Technik, 119, 131-137.

  11. Lewallen R, Quanbury AO, Ross K & Letts RM (1985). A biomechanical study of normal and amputee gait. In International Ser Biomechanics, vol 5A, Human Kinetic Publishers, Champaign, Illinois, 587-592.

  12. Murray MP, Mollinger LA, Sepic SB & Gardner GM (1983). Gait patterns in above-knee amputee patients: hydraulic swing control vs constant friction knee components. Archives of Physical Medicine & Rehabilitation, 64, Aug, 339-345.

  13. Nolan L, Wit A, Dudzinski K, Lees A, Lake M, Wychowanski M (2003). Adjustments in gait symmetry with walking speed in trans-femoral and trans-tibial amputees. Gait & Posture, 17, 2, 142-151.

  14. Oberg K & Lanshammar H (1982). An investigation of kinematic and kinetic variables for the description of prosthetic gait using the ENOCH system. Prosthetics & Orthotics International, 6, 43-47.

  15. Orendorff M, Segal A, Klute GK, McDowell ML, Pecoraro JA & Czerniecki JM (2006). Gait efficiency using the C-Leg. Journal of Rehabilitation, Research & Development, 43, 2, 239-246.

  16. Orendurff M, Segal A, McDowell M, Klute G, Williams R, Turner A, Pecoraro J, Czerniecki J (----). C-Leg does not improve stance phase knee flexion or walking efficiency in older transfemoral amputees. ISB XXth Congress - ASB 29th Annual Meeting, July 31 - August 5, Cleveland Ohio.

  17. Schmalz T, Blumentritt S, & Jarasch R (2002). Energy expenditure and biomechanical characteristics of lower limb amputee gait: the influence of prosthetic alignment and different prosthetic components. Gait & Posture, 16, 255-63.

  18. Segal, AD et al (2006). Kinematic and kinetic comparisons of transfemoral amputee gait using C-Leg® and Mauch SNS® prosthetic knees. Journal of Rehabilitation, Research & Development, 43, 7, 857-870.

  19. Seroussi RE, Gitter A, Czerniecki JM, & Weaver K (1996). Mechanical work adaptations of above-knee amputee ambulation. Archives of Physical Medicine & Rehabilitation, 77, Nov, 1209-1214.

  20. Stein JL, & Flowers WC (1987). Stance phase control of above-knee prostheses: knee control versus SACH foot design. Journal of Biomechanics, 20, 1, 19-28.

  21. Waters RL, Perry J, Antonelli D, & Hislop H (1976). Energy cost of walking of amputees: the influence of level of amputation. American Journal of Bone & Joint Surgery, 58, 1, 42-46.

  22. Winter DA, Olney SJ, Conrad J, White SC, Ounpuu S & Gage JR (1990). Adaptability of motor patterns in pathological gait. In: Winters JM, & Woo SL-Y (eds) Multiple Muscle Systems: Biomechanics and Movement Organisation. Springer-Verlag, New York. 680-693.

  23. Zuniga EN, Leavitt LA, Calvert JC, Canzoneri J & Peterson CR (1972). Gait patterns in above-knee amputees. Archives of Physical Medicine & Rehabilitation, 53, 373-382.

  24. Goujon-Pillet H, Sapin E, Fode P & Lavaste F (2008). Three-dimensional motions of trunk and pelvis during transfemoral amputee gait. Archives of Physical Medicine & Rehabilitation, 89, 1, 87-94.

  25. Sjödahl C, Jarnlo G-B, Söderberg B, & Persson BM (2002). Kinematic and kinetic gait analysis in the sagittal plane of trans-femoral amputees before and after special gait re-education. Prosthetics & Orthotics International, 26, 101-112.

  26. Sjödahl C, Jarnlo G-B, & Persson BM (2001). Gait improvement in unilateral trans-femoral amputees by a combined psychological and physiotherapeutic treatment. Journal of Rehabilitation Medicine, 33, 114-118.

  27. Tazawa E (1997). Analysis of torso movement of trans-femoral amputees during level walking. Prosthetics & Orthotics International, 21, 129-140.

  28. Jaegars SMHJ, Arendzen JH & de Jongh HJ (2006). An electromyographic study of the hip muscles of transfemoral amputees in walking. Clinical ORthopaedics & Related Research 328, 119-128.

  29. Van der Linden MI, Twiste N & Rithalia SVS (2002). The biomechanical effects of the inclusion of a torque absorber on trans-femoral amputee gait, a pilot study. Prosthetics & Orthotics International, 26, 35-43.

  30. Bellman M, Schmalz T & Blumentritt S (2010). Comparative biomechanical analysis of current micro-processor controlled prosthetic knee joints. Archives of Physical Medicine & Rehabilitation, 91, 644-652.

  31. Hof AL, van Bockel RM, Schoppen T & Postema K (2007). Control of lateral balance in walking. Experimental findings in normal subjects and above-knee amputees. Gait & Posture, 25, 250-258.

  32. Kaufman KR, Levine JA, Brey RH, Iverson BK, McCrady SK, Padgett DJ & Joyner MJ (2007). Gait and balance of transfemoral amputees using passive mechanical and microprocessor-controlled prosthetic knees. Gait & Posture, 26, 489-493.

  33. Stein JL & Flowers WC (1987). Stance phase control of above-knee prostheses: Knee control versus SACH foot design. Journal of Biomechanics, 20, 1, 19-28.

  34. Winter DA & Sienko SE (1988). Biomechanics of below-knee amputee gait. Journal of Biomechanics, 21, 361-367.

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Information compiled by Tony Fitzsimons, June 2010.
Updated January 2012.