Through-knee amputation is a common amputation level after battlefield injuries during the medical evacuation process. However, there are limited data comparing through-knee amputation with transfemoral amputation as a definitive amputation level in terms of gait parameters.
(1) Does through-knee amputation result in improved gait velocity when compared with matched transfemoral amputees? (2) Do through-knee amputees have a faster gait cadence than matched transfemoral amputees? (3) Do through-knee amputees have a different stride length or stride width than matched transfemoral amputees? (4) Does through-knee amputation result in decreased work of ambulation when compared with matched transfemoral amputees?
Between January 2008 and December 2012, six male active-duty military patients who had undergone unilateral through-knee amputations as a result of trauma underwent gait studies at our institution. Of those, four of six underwent gait analysis after being able to walk for at least 3 months without assistive devices, and this group was studied here. Most through-knee amputees who were not included had elective revisions of their amputations from through-knee to a transfemoral amputation before completing 3-month gait data. Each of the amputees studied was matched to a transfemoral amputee based on height, body mass index, and contralateral amputation level resulting in a case-control study of active-duty military male amputee patients. Inclusion required complete gait data collected while walking at a self-selected pace wearing custom prosthetic devices. The through-knee amputees had a median (range) age of 32 years (23-41 years) and the transfemoral amputees had a median age of 24 years (22-27 years). Three-dimensional gait data were collected and analyzed. A power analysis found that to detect a clinically important difference (set at a change in work of ambulation of 1 J/kg*m) with a p value of 0.05 and a β set to 0.2, a study population of 56 patients per group would be required; that being said, our results on a much smaller population must be considered exploratory.
With the numbers available, we found no differences in gait velocity when comparing through-knee (1.18 m/sec) and matched transfemoral amputees (1.20 m/sec, difference of medians = 0.02 m/sec; p = 0.964). Likewise, we found no differences in gait cadence when comparing through-knee with transfemoral amputees (104 versus 106 steps/min, respectively, difference of means 2 steps/min, p = 0.971). There was no difference in stride length or stride width when comparing through-knee (70 cm and 18 cm, respectively) with transfemoral amputees (70 cm and 19 cm, respectively; p = 0.948 and p = 0.440). With the numbers available, we did not identify a difference in the work of ambulation for through-knee amputees when compared with matched transfemoral amputees (8.3 versus 7.5 J/kg, respectively; p = 0.396).
Based on our findings, we are unable to demonstrate any functional advantages of knee disarticulation over transfemoral amputation. Although there are theoretical advantages for maintaining an intact femur during the medical evacuation and serial débridement process, we question the utility of knee disarticulation as a definitive amputation level; however, larger numbers of patients are needed to confirm these results.
Level III, therapeutic study.
D. J. Schuett, US Naval Hospital, Okinawa, Japan
M. P. Wyatt, T. Kingsbury, N. Thesing, K. M. Kuhn, Naval Medical Center San Diego, San Diego, CA, USA
D. M. Dromsky, Orthopedics Department, Conroe Regional Medical Center, Conroe, TX, USA
D. J. Schuett, US Naval Hospital, PSC 482, Box 1600, FPO, APO 96362, Okinawa, Japan, email: firstname.lastname@example.org
Each author certifies that neither he or she, nor any member of his or her immediate family, has funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.
Clinical Orthopaedics and Related Research® neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA-approval status, of any drug or device prior to clinical use.
Each author certifies that his or her institution approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.
This work was performed at the Naval Medical Center San Diego, San Diego, CA, USA.
Dustin J. Schuett, Marilynn P. Wyatt, Trevor Kingsbury, and Kevin M. Kuhn are employees of the US Government and this work was prepared as part of their official duties. The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Department of the Navy, Department of the Army, Department of Defense, nor the US Government. Nothing in the presentation implies any Federal/Department of Defense/Department of the Navy endorsement.
Received October 04, 2017
Received in revised form December 29, 2017
Accepted January 17, 2018