Observations on trans-tibial amputations for trauma

Michael Saleh

Mike Saleh is a practicing Consultant Orthopaedic Surgeon with a special interest in major trauma, reconstruction after trauma and amputation surgery and amputation rehabilitation.

He is a (retired) Professor of Orthopaedic and Traumatic Surgery, University of Sheffield, a Past President of the British Limb Reconstruction Society and a Fellow of the British Orthopaedic Association.

Over his career Mike has presented widely both in the UK and overseas and has published some 256 books, chapters, journal articles and training manuals.

 

 

Abstract

Burgess wrote in 1988¹ that

“surgeons carrying out below-knee amputation should first understand that this is not inconsequential surgery: it offers a significant technical challenge”.

Between 1978 and 1983 I worked in orthopaedics in Dundee as a registrar, then a lecturer and finally a research fellow. At the time George Murdoch was the Professor of Orthopaedics and he had built up a formidable team dedicated to amputation surgery and rehabilitation with consultants Mike Turner and Alistair Swanson performing amputation surgery lists, Dr Ian Troup supervising their surgical recovery and rehabilitation and David Condie a bioengineer in charge of research and development. I was fortunate enough to work with all of these individuals developing a passion for the subject and a life-long professional interest. There were two dedicated theatre lists per week at King’s Cross Hospital taking mainly dysvascular cases. After the immediate post-operative period patients would travel by ambulance alongside the south bank of the beautiful River Tay estuary to the Dundee Limb Fitting Centre (DLFC) in Broughty Ferry where they undertook in-patient rehabilitation². The importance of preservation of the knee joint was established and careful surgery and aftercare meant that the majority of cases were successfully rehabilitated at the below-knee (trans-tibial) rather than the above knee level. There were also cases coming through the trauma unit and these cases were channelled into the same protocol. Such was the standard of work in Dundee that a conference was convened in 1985 with 60 speakers including myself from all over the world and a state of the art publication produced³.

My MSc thesis supervised by Dr Mick Jarrett in the gait analysis laboratory was directed towards the effects of deliberately produced malalignments on trans-tibial amputee gait⁴. The results were published in the Journal of Bone and joint surgery⁵ with George Murdoch as co-author. The results were also presented in Edinburgh in 1996 for the Syme Professorship and Gold Medal of the Royal College of Surgeons of Edinburgh. Interestingly of the five test subjects the single post trauma case was by far the most successful at coping with the alignment changes. The MSc gave me a fundamental understanding of forces and their effects and the importance of establishing precise alignment to mitigate against moments derived from malposition a situation frequently encountered in fracture management.

After Dundee I took up a consultant post in Sheffield and became Professor of Orthopaedics in 1995. My interest in alignment in long bone fracture surgery resulted in the establishment of the first Limb Reconstruction Unit in the country where precise techniques were used to restore alignment and length in fractured limbs. I developed an external fixator the Sheffield Ring Fixator, SRF⁶ and acute and progressive correction methods for realigning femoral and tibial fractures respectively. Unlike the gait laboratory, static rather than dynamic analysis using accurate weight bearing imaging was used to derive the centre of rotation of angulation where hinge devices such as the SRF could then be used to correct the deformity.

I also continued my involvement in amputation surgery performing amputations on cases admitted to the trauma unit in Sheffield and running a subregional speciality clinic with my rehabilitation colleague Dr Dipak Datta. This clinic proved to be a fertile environment for surgical trainees many of whom continued to offer amputation expertise in their substantive posts. Rehabilitation clinics like this one and DLFC once the recipient of mainly vascular cases are seeing relatively more trauma cases as busier roads and successful resuscitation techniques have led to an increasing number of people with post trauma amputations. These mainly young people with amputations have high expectations for both work and recreation, in part fuelled by positive media coverage. Whilst we know that trans-tibial amputation coupled with modern prosthetics can restore mobility there is a paucity of information regarding outcomes following amputation for trauma. Catering for these changes in population profile may mean reviewing our rehabilitation programmes and understanding this patient group better. Research reviews are difficult in such a heterogeneous population. Clearly function and mobility will depend on the degree of damage to the residual limb and the other injuries sustained. It would seem to me that the only appropriate endpoint would be the quality of the stump stratified against the extent of local injury. Endorsing this view I have found myself naturally migrating to the admission details and operation notes with each new case I evaluate

Some stump quality scoring systems^7,8,9 have been described in a general rehabilitation setting but none have been validated. For this type of study a scoring system addressing all the most important surgical characteristics is ideal since it would guide both assessment and surgical treatment. The scoring system used in this study was derived from my training in Dundee and my subsequent experience and operative publication¹⁰. The extent of the local injury is difficult to define but may be inferred from information on the necessity to perform the amputation acutely (ie timing of amputation) and the Zone of Injury (ZOI). I am not aware of any studies in the literature using this approach.

A retrospective study of a consecutive series of 100 trans-tibial residua in 97 patients referred to my practice from all over the United Kingdom was carried out. The case records were pseudonymised in an attempt to reduce observer bias and ensure patient confidentiality. There were 84 males and 13 females with a mean age of 44 (range 19-73). Assessment of the stump was carried out at a mean of 23 months after prosthetic fitting (range 3-70m). Since 64 out of 97 patients had significant other injuries functional scores were not used. Their general mobility was reflected in the SIGAM score¹¹ and hours of prosthetic limb use. There were 59 “full time limb users” ( >40hrs/week), 28 on limited use and 5 cases in which prosthetic limb use had not commenced or had failed. Using the SIGAM scale there were 8 grade A&B cases, 24 grade C&D cases and 60 grade E&F cases (A-F scale with F being the highest mobility level). There was a strong correlation between SIGAM grade and hours of prosthetic use (r=0.76).

The quality of the residuum was derived from six key parameters (muscle pad, skin quality, bone shape, bone length, nerve irritation and knee joint) which were each scored 1-3 with 1 being good and 3 poor. The data were analysed on three separate occasions. There were 45 cases with a score of <8 and these were considered good results with no indication for surgical revision. There were 47 cases with a score of 8-12 and these were considered borderline, there being potential for improvement with prosthetic adjustment and/or surgery. There were 8 cases with a score >12 considered to be poor and where revision surgery should be considered if clinically indicated. There were therefore 55 cases where suboptimal stump quality was identified.

The timing of amputation was used as one criteria reflecting local injury and three time points were used; “AI” acute immediate (within 24 hours) and therefore most severe, “AD” acute delayed (<1year) and “L” late – least severe (1year or >). The best results were seen in the L cases n=32 score 8.0 and the worst results were seen in the AI group n=23 score 10.3 with the AD group scoring somewhere in between n=45 score 9.4.

Local injury was also assessed by looking at the zone of injury. ZOI was defined as the area from the top of the epicondyles of the knee to the level of the malleoli. The better results were seen as expected in the non zone of injury cases n=21 score 8.57 compared to the ZOI cases n=79 score 9.33. When these two conditions (timing and ZOI) were combined the “Late” group with 22 ZOI cases scored 8.4 and 10 Non ZOI cases scored 7.4 the latter representing the most favourable condition and results. The AI group were all ZOI injuries scoring 10.3.

Of the stump parameters the muscle pad, skin and bone shape were generally least well achieved or maintained. Surgeons frequently misrepresented a myoplasty as a myodesis but the latter only exists if the muscle is physically fixed into the bone. The muscle repair and skin might be compromised by the quality of tissues available following injury. The bone shape would, most probably be influenced by the skill and experience of the surgeon unless exostoses developed. Bone length, nerve irritation and knee joint function all scored much better and interestingly knee joint motion was excellent and much better than one used to see with dysvascular cases.

Some of the poorer results may have been due to late sequelae which are mostly outside the surgeon’s control. Late sequelae were recorded in 50 patients who showed one or more of the following; soft tissue redundancy after residuum shrinkage and end pad subluxation (32), neuromata – not all problematic (22) and exostoses (11).

The limitations of this study are clear; the scoring system requires validation and with six parameters and five conditions one would need a cohort of several thousand cases to achieve statistical significance. Nevertheless there are trends in the study which might help to direct and improve current treatment protocols.

The population is probably reasonably representative of those attending regional mobility centres and for this reason bilateral cases were deliberately included. There was a wide spectrum of mobility levels as judged by hours of prosthetic use and the SIGAM scale. Hours of prosthetic use may be misleading since amputees living in non-adapted environments may keep their legs on for longer periods out of necessity. There was however a strong correlation between SIGAM grade and hours of prosthetic use (r=0.76).

In view of the small sample size the author has avoided any “second level” analysis but some general observations are offered:

• The scoring system appears to be a sensitive tool for stump evaluation and directing treatment. It will however need further study and validation.
• Using the scoring system 55/100 had residual stump issues potentially amenable to treatment.
• The acute amputations had a distinctly poorer outcome.
• The late cases typified by the failing foot after foot injury had a much better outcome.
• Late sequelae were seen in 50/100 stumps indicating the need for regular clinical and radiological follow up.

Multidisciplinary assessments are now routine in many centres. As we see more trauma related cases there is a need to include a trauma surgeon in the process. The advantages of a system like this are clear since the surgeon will get to see first-hand the practical effects of his stump surgery on prosthetic use and performance. It will provide the necessary background detail for revision surgery to be properly directed. It will create a fertile environment for surgical trainees and perhaps stimulate more recruits into this under represented field.

The study population had a total of 82 other lower limb injuries. Whilst the majority will have healed satisfactorily there were 12 cases in whom a significant malunion either affecting the amputated side (4 cases) or the other leg (8) was thought to be affecting function. With an orthopaedic review these deformities could be identified, referred and treated. In my own practice following limb reconstruction principles femoral derotation, axial corrections in the femur and upper tibia and knee release surgery (quadricepsplasty) have been performed on a fairly regular basis. Where axial deformity exists in the upper tibia conventional prostheses have the capacity to compensate for around 7º of angulation (depending on the deformity level). I have performed simultaneous corrective osteotomy and amputation where larger deformities exist.

This report does not consider osseointegration and whilst currently it is considered as a salvage for the short residuum with improved techniques it may in future become more main stream.

References

1. Burgess EM. Below-knee amputation. Surgery, including levels, alternative techniques, growth period.In: Murdoch G and Donovan RG (eds) Amputation surgery and lower limb prosthetics. Oxford: Blackwell Scientific Publications, 1988, pp. 37-40

2. Troup IM, Wood MA. Residuum dressings. In Total Care of the Lower Limb Amputee. London: Pitman, 1982, pp. 67-75.

3. Murdoch G, Donovan RG. Amputation Surgery and Lower limb Prosthetics. Blackwell Scientific Publications 1988.

4. Saleh M. A study of prosthesis alignment changes on the gait of below-knee amputees. MSc (Bioengineering) University of Dundee 1982.

5. Saleh M, Murdoch G. In defence of gait analysis: Observation and measurement in gait assessment. Journal of Bone and Joint Surgery, 1985;67-B: 237-241. Cited Whittle M; Gait Analysis - an introduction. Butterworth-Heinemann 1991.

6. Ali A, Burton M, Hashmi M, Saleh M. Outcome of complex fractures of tibial plateaus treated with a beam loading ring fixation system. J Bone Joint Surg Br: 85-B(5): 691-699, July 2003.

7. Sooriakumaran S, Uden M, Mulroy S, et al. The impact a surgeon has on primary amputee prosthetic rehabilitation: A survey of residual lower limb quality. Prosthet Orthot Int 2018; 42: 428-436.

8. Persson M, Liedeberg E. A clinical standard of residuum measurement and classification in lower limb amputees. Prosthet Orthot Int 1983; 7: 17-24.

9. Chakrabarty BK. An audit of the quality of the residuum and its relation to rehabilitation in lower limb amputees. Prosthet Orthot Int 1998; 2: 136-46.

10. Saleh M. Amputation surgery. In: Evans DK (ed) Operative Orthopaedics. London: Blackwell Scientific Publications 1993, pp. 420-60.

11. Ryall NH, Eyres SB, Neumann VC, Bhakta BB, Tennant A. The SIGAM mobility grades: a new population-specific measure for lower limb amputees. Disabil Rehabil. 2003 Aug 5;25(15):833-44.