Skew flap versus long posterior flap on below-knee amputation in patients with peripheral vascular disease

Skew flap versus long posterior flap on below-knee amputation in patients with peripheral vascular disease

Ahmed Kamal Gabr, MD; Hossam M. Saleh, MD; Sherif Moaamen Aboshloaa, MD

Department  of Vascular Surgery, Ain Shams University, Cairo, Egypt.

Background/Aim: Below-knee amputation (BK) is the most proximal amputation that is still associated with a good rehabilitation  procedure. All variations of the transtibi al amputation are designed to provide adequate distal end padding and produce a cylindrical stump that can be readily suitable for prosthesis. The aim of this study is to compare the skew flap and the long posterior flap below-knee  amputation  in patients with peripheral  vascular  disease in terms of stump healing,  wound infection,  reamputation rate, and mobility with a prosthetic limb as outcome measures.

Patients and methods: Fifty patients with chronic atherosclerotic occlusive disease of the lower  extremity  and  critical  ischemia  (intractable  rest pain,  ulcer  or gangrene)  for whom no other treatment  options remained  and in whom  below-knee  amputation  is indicated  are included in the  study. Patients  were randomized  into two groups. Group 1 underwent  Skew Flap BKA; Group 2 underwent  long posterior flap BKA. The two groups will be compared in terms of stump healing, wound infection, prosthesis fitting rate, and mobility with a prosthetic limb. Statistical analysis  by Chi-square and t-test was used to compare two groups as regard quantitative variables in parametric data (SD<25% mean).

Results:  Regarding the early post-operative outcomes in terms of death in the 30 days post­ operative period, incidence of cardiac events within 30 days post-operatively, primary healing after 7 days, wound discharge after 7 days, incidence of minor edge necrosis after 7 days, major flap necrosis after  7 days, revision of stump &  post-operative  stay period. Comparing the 2 tested groups using the Chi square showed no significant statistical differences between both of them. Regarding the late outcome results including the survival within 6 months, among the

25 patients of group 1, 20 patients survived till 6 months postoperatively (80% survival rate),

while among the 25 patients of group 2, 18 patients survived till 6 months postoperatively (72%

survival rate). Regarding prosthesis fitted within 6 months, among the 20 patients of group 1,

5 patients used the below knee prosthesis (25%),  while among the 18 patients in group 2, 3 patients used the prosthesis (18.18%). Regarding the mobility status of patients with 6 months post-operative: among the 20 patients of group 1, among 20 patients of group 1, 3 patients were immobile (16.67%), 12 patients were dependent (60%), and 5 patients were independent (25%). While among the 18 patients of group 2: 2 patients were immobile (11.11%), 13 patients were dependent (72.22%) and 3 patients were independent (16.67%). By comparing the two groups regarding the mobility status within 6 months post-operative, there was no significant statistical difference using Chi square.

Conclusion: The skew flap technique is considered the routine procedure for below knee amputation in many centers around the world. We conclude that the skew flap is just as effective as the long posterior flap. Skew flap is especially useful when below knee amputation is indicated and the posterior skin is inadequate to construct a long posterior flap.

Key words:  Trans-tibial amputation, skew-flap, long posterior flap.

Introduction:

Amputation  of  a  damaged  limb  is  one of the oldest and, arguably, most effective surgical procedures. A properly performed amputation  holds the  promise of pain relief for patients with advanced ischemia & control of infection in the setting of extremity sepsis. Unfortunately, vascular surgeons often regard amputation  as the terminal  battle in the war against atherosclerosis and an admission of personal failure.l Transtibial (below-knee) amputation is indicated when gangrene or infection  precludes  a more distal  procedure and for intractable ischemic rest pain that cannot be corrected by lower extremity revascularization. Below-knee amputation (BK)  is the  most  proximal  amputation  that is still associated with a good rehabilitation procedure. All variations of the transtibial amputation are designed to provide adequate distal end padding and produce a cylindrical stump that can be readily cast for a procedure.2

The surgeon should aim to provide adequate tissue  cover  over the  end  of the transected tibia and avoid placing of the suture lines at sites subject to pressure from a below-knee prosthesis.3 The success ofthe long posterior flap in obtaining sound healing at below-knee level  is widely  recognized  in  patients  with ischaemic disease, and since this method was introduced  in 1967 by Burgess and Romano, the  number  of patients with healing  below­ knee  amputations  in ischaemic  disease  has dramatically  increased,  and  with  improved methods oflevel selection this proportion may increase further.4 However, the long posterior flap below-knee stump has several problems. The  stump  may  be  wide  in the  transverse diameter causing difficulties in delay in limb fitting; the scar crossing the tibia may break down with prosthetic use, and to avoid these problems we undertook a review of the basic design of the below knee amputation  stump to utilize the best available blood supply and avoid these difficulties. Sagittal flaps result in the anterior part of the incision, and therefore the scar overlying the anterior crest ofthe tibia is exposed to pressure from  patellar tendon bearing socket.  If the  line of the  incision  is rotated  by 150, the  scar  is brought  2.0 em

lateral to the crest of the bone, which results in skewed flaps and the scar is removed from the point of high pressure. 5 The aim of this study  is to  compare  the  skew  flap  and the long  posterior  flap  below-knee  amputation in  patients  with  peripheral  vascular  disease in terms of stump healing, wound infection, reamputation rate, and mobility with a prosthetic limb as outcome measures.

Patients and methods:

This comparative randomized prospective study was conducted at Ain Shams University hospitals and two tertiary referral hospitals in Saudi Arabia in the  period from  September

2010 to December  2012. Fifty patients with

chronic   atherosclerotic    occlusive    disease of the lower extremity and critical ischemia (intractable  rest pain, ulcer or gangrene) for whom  no other treatment  options remained and in whom below-knee amputation was indicated were included in the study. Patients were randomized into two groups. Group 1 (n=25) underwent skew flap BKA; Group 2 (n=25)  underwent  long posterior flap BKA. All patients signed an informative written consent. The preoperative  information obtained for each group includes: age, sex, mean  age,  smoking,  diabetes,  CBC,  renal and liver profiles, cardiac, renal, neurologic and hepatic comorbidity, indications for amputation as rest pain, necrosis or both, Previous surgical reconstruction (ipsilateral arterial reconstruction, ipsilateral angioplasty, ipsilateral foot amputation and contralateral major amputation).

The  two   groups   will   be  compared   in terms of the above mentioned pre-operative information.

The early outcome for each group includes:

1) Death in the early post-operative period

(within 30 days).

2) Cardiac and other major events (e.g. Stroke).

3) State of healing  at 1 week: a) Primary healing. b) Wound discharge. c) Minor wound edge necrosis. d) Major flap necrosis leading to revision to above-knee amputation.

4)   Revision   of   amputation   stump:   a) No  revision.   b)  Revision   at  same  level.

c) Revision to higher level.

5) The average length of post-operative stay.

The early outcome for each group will be compared in terms of the above mentioned data.

Late outcome at 6 months will be assessed

in terms of:

1) Limb fitted with prosthesis at 6 months.

2) Mobility at 6 months (immobile, dependent or independent).

Late outcome of each group will be compared. Statistical analysis by Chi-square and t-test  was used to  compare  two  groups as regard quantitative variables in parametric data (SD<25% mean).

Results:

This comparative randomized prospective study was conducted at Ain Shams University Hospital, Almoosa Specialized  Hospital and Tabouk Military Hospital in KSA in the period from  September  2010  to  December  2012. Fifty patients with chronic atherosclerotic occlusive disease of the lower extremity and critical ischemia (intractable  rest pain, ulcer or gangrene) for whom no other treatment options remained and in whom below-knee amputation   was   indicated   were   included in the study. Patients  were randomized  into two   groups.   Group   1  (n=25)   underwent Skew Flap BKA; Group 2 (n=25) underwent long posterior flap BKA. All patients signed an  informative  written  consent.  Table (1) demonstrates         patients'         demographic data together with risk factors, comorbid conditions, indications for amputation and previous    surgical    operations.    Regarding all  the  pre-operative  factors  including  the age, sex, smoking, diabetes, pre-operative morbidities, previous surgical reconstruction and indication for the amputation: comparing the  2  tested  groups  using  the  Chi  square showed no significant statistical differences between both ofthem.

Regarding      the      early      post-operative

outcomes  in terms  of death  in the  30  days post-operative period, incidence of cardiac events  within  30  days  post-operatively, primary healing after 7 days, wound discharge

after 7 days, incidence of minor edge necrosis after 7 days, major flap necrosis after 7 days, revision   of  stump   &  post-operative   stay period are shown in Table (2). Comparing the

2 tested groups using the Chi square showed no significant statistical differences between both of them Table (2).

Regarding  the  late  outcome  results including   the   survival   within   6   months, among the 25 patients of group 1, 20 patients survived till 6 months postoperatively (80% survival  rate), while  among the  25 patients of  group   2,   18  patients   survived   till   6 months postoperatively (72% survival rate). Regarding prosthesis fitted within 6 months, among the 20 patients of group 1, 5 patients used the below knee prosthesis (25%), while among the 18 patients in group 2, 3 patients used the prosthesis (18.18%) Table (3).

Regarding  the mobility  status of patients

with 6 months post-operative:  among the 20 patients  of  group  1, among  20  patients  of group 1, 3 patients were immobile (16.67%),

12 patients were dependent (60%), and 5 patients were  independent  (25%). While among the 18 patients of group 2: 2 patients were immobile (11.11%), 13 patients were dependent (72.22%) and 3 patients were independent   (16.67%).   By  comparing   the two  groups  regarding   the   mobility  status within  6  months  post-operative,  there  was no significant statistical difference using Chi square. Table (4).

Discussion:

The  success  of  the  long  posterior  flap in  obtaining  sound  healing  at  below-knee level is widely recognized in patients with ischemic disease, and since this method was introduced in 1967 by Burgess and Romano, the number of patients with healing below­ knee amputations in ischemic disease has dramatically increased, and with improved methods  of  level  selection  this  proportion may increase further.4  However, the long posterior flap below-knee stump has several problems. The stump may be wide in the transverse     diameter    causing    difficulties in  delay  in  limb  fitting;  the  scar  crossing the  tibia  may  break  down  with  prosthetic

use, and to  avoid these  problems  Robinson undertook  a  review  of  the  basic  design  of the  below knee amputation  stump to utilize the  best  available  blood  supply  and  avoid these difficulties. Very little separation ofthe skin from the  muscle flap occurs  when this is performed,  and no significant  perforating arteries are divided.S Spence and McCollum, using  thermography   and  oximetry,  suggest that the least good blood supply to the skin at this  level is  on the  lateral  aspect  of the stump. Ifthe flap is based on the distribution of the sural nerve artery and the saphenous nerve artery, then a posterolateral flap and an anteromedial flap results. If any deficiency is revealed  in the  lateral skin, this flap can be shortened  in relation to the medial flap. The skew  flaps appear  to  make  best  use  of the inflow  from  these  two  cutaneous  arteries.5

In our study we compared  between the two

types  of below knee  amputations:  the skew flap BKA described by Robinson and long posterior flap BKA as described  by Burgess and Romano. We compared the early outcome between the two groups in terms of: death during the early post-operative period (within

30 days), the cardiac and other major events

post-operatively,  state of healing  at 1 week post-operatively, the need of the revision of the amputation stump and the average length of  the   post-operative   stay.  We  compared the  late outcome  at 6  months  between the two  groups  in  terms  of:  limb  fitted  with prosthesis at 6 months, mobility status during the 6 months follow up. Out of fifty patients recruited in our study, only 38 patients were available at the end of the study due to death of  12  patients.  5 patients  died  in the  early postoperative  period  (30 days),  and further

7 died within 6 months postoperatively.  The

two groups were well matched  in respect to age, sex, smoking, diabetes, co-morbidities, indication     for   the    amputation    and   the previous surgical reconstruction. We found only 2 studies comparing the outcome of both long posterior flap and skew flap below knee amputation. The first one was a retrospective review of major lower limb amputations in Derby  between  October  1979  and  October

1986, taking April1983 as the dividing point

for the two 3 and half year periods as it was then that the skew flap (SF) below-knee amputation  was adopted.7  In the first period

211 amputations were performed,  and in the second  142. The  indication for  surgery was irrevocable ischaemia in the majority, diabetic gangrene being responsible for the remainder. There was no significant difference between the  long posterior  flap (LPF)  and the skew flap (SF) groups with respect to the incidence of  diabetic  gangrene.  The  case  notes  were analyzed for patient's  age, previous vascular surgery, coex1stmg       medical            conditions, indications  for surgery, operation  performed and operative mortality. Operative mortality is defined as death occurring within 30 days of the most recent  operation.8  A commonly employed  method  of comparing  the  results of  amputations  is to  look  at the  length  of time spent in hospital in each of the groups. In that  study  a random  sample  of 75  cases was examined for correlation between length of  hospital  stay  and time  to full  healing.7,8

The second study was a multicenter trial in which surgeons in 11 centers randomized 191 patients with end-stage occlusive vascular disease to two different methods of stump construction. The skew flap technique was performed  in 98 and the long  posterior flap was performed  in 93. The two  groups  were well matched in respect to age, sex, smoking, diabetes,   and   indications   for   amputation. Early  outcome  was  compared  in  terms  of

30-day mortality rate; the state of the wound

at 1 week; the need for  surgical revision  at the  same  level,  and  revision  to  a  higher level.  Follow-up  information  at  6  months was available from records or by mailed questionnaire  in 188 (98%) at 6 months,  20 died during that interval.2

In our study, amongthe 25 patients of group

1 : 2 patients (8%) died in the 30 days post­ operative period, while among the 25 patients of  group  2: 3  (12%)  patients  died.  These differences  were not statistically  significant. Our  results  were  comparable  to the  results of  Harrison  et al. There  was no significant difference between the operative mortality in the  long posterior flap group (4/21 patients) and   the   skew   flap  group   (3/38   patients)

80

70

60

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40

30

20

1

Groupl                        Groupn

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Figure    (1):    Rlustrative     diagram    of   the technique of skewflap below knee amputation.6

Figure (2): Descriptive statistics of prosthesis fitted within 6 months.

%

80

70

60

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40

30

20

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2======= -- ====

Figure (3):  Descriptive statistics of mobility status within 6 months.

dming the petiod 1983-86.7 Om results were also comparable to those ofRuckley et al. He rep01ted that death in the early postoperative period (within 30  days) occmTed in 27 patients: 11 (11%) skew flap and 16 (17%) long posterior flap patients. These differences were not statistically significant.2

In our study, among the 25 patients of group 1: 13 patients had primary healing within 7 days post-operative (52 %) while among the 25 patients of group 2:11 patients had p1imruy healing (44%). These differences were not statistically significant. Among the

25 patients of group 1:12 patients had wound

dischatge after 7 days post-operative (48%). while among the 25 patients of group 2: 14 patients had wound dischru·ge (56%). These differences were not statistically significant. Among the 25 patients of group 1: 5 patients had minor edge necrosis (20%). while among the 25 patients of group  2 : 7  patients had minor edge necrosis (28%). These differences

were not statistically significant. Among the

25 patients of group 1 : 2 patients had major flap necrosis (8%). while among the 25 patients of group 2:3 patients had major flap necrosis (12%). These differences were not statistically significant.

Regru·ding revision of the stump: among the 25  patients of group  1 : 2  patients had revision at the same level (8%) and 1 patient had revision at a higher level (4%), while among the 25 patients of group 2 : 1 patient had revision at a same level (4%) and 1 patient had revision at higher level (4%). These differences were not statistically significant.

Om results were also compru·able to those ofRuckley et al. In respect to primruy healing at 1 week, the two groups were identical at

60%. Wound dischru·ge or minor wound edge necrosis wasobservedin21 (21%) ofthe skew flap and 26 (24%) of the Bmgess stumps. Major failure of healing led to revision to the above-knee level in 10 (10%) after skew and

Table  1:  Patients'  demographic data,  risk  factors,  comorbid  conditions,  indications for amputation and previous surgical operations.

in 7 (8%)  after Burgess  operation.2 Harrison et  al., stated  that  time to  full  stump  healing was  significantly  shorter   in  the   skew  flap group  compared to the long posterior flap amputations (P = 0.001),  which  could not be concluded from our study.7

Regarding stump failure requmng conversion to an above knee amputation, our results  were  comparable to  results  reported by  Harrison  et al.  Stump  revision  requiring above  knee  amputation occurred in only 5.3 per cent of skew flap amputations compared to 11.3 per cent in the Burgess  long posterior flap  amputations,  although   this   just  failed to   reach   statistical  significance.  Harrison

stated   that   his   expenence  shows   that  the rate of primary  healing  is significantly better following a skew flap  amputation than  after a Burgess long posterior flap below-knee amputation,  allowing  a  higher   proportion of  below-knee amputations to be performed with  a trend  toward  fewer  stump  failures.7

This   conclusion  by   Harrison   et   al.,   was not  supported by  our  results  nor the  results reported  by Ruckley  et al., which showed no statistically  significant  differences  between the   two    groups    regarding   stump    failure and  the  need  of  revision  using  above  knee amputation.  Regarding  the   average   length of  the  post-operative stay:  for  group  1 the

Table 2: Early outcome.

Table (3): Descriptive statistics of prosthesis fitted within 6 months.

Table (4): Descriptive statistics of mobility status within 6 months.

average period was 6.46 days (SD 4.9) (range from 2 to 18 days), while for group 2 the average period was 7 days (SD 4.27) (range from  2 to 16 days). These differences  were

not statistically significant.2,7 Ruckley stated the average length of postoperative stay in the surgical wards was 36 days after skew and 42 after  Burgess  operation.  These  differences

were not statistically significant.2

Among   the  25  patients   of  group   1 : 20 patients  survived  till 6 months  postoperative (6  months  survival  rate  80%),  while  among the 25 patients of group 2: 11patients survived (6 months survival rate 73.33 %). These differences were not statistically significant. Our  results  were  also  comparable to  those of  Ruckley  et al.  He stated  that  20 patients had died (9 skew  and 11 Burgess)  during the

6  months  follow-up  period.2  In  our  study,

among the 20 patients  of group  1 : 5 patients used   the   below    knee    prosthesis    (25%). while  among  the  18  patients  of  group  2 : 3 patients  used the prosthesis (18.18%). These differences were not statistically significant.

Regarding the  mobility  status  of the patients  within  6 months  post-operative: among the 20 patients  of group  1 : 3 patients were immobile (16.67%), 12 patients were dependents (60%)  and  5 patients  were independents (25%).  While among the  18 patients of group 2 : 2 patients  were immobile (11.11%),  13  patients   were  dependents (72.22%) and 3 patients  were independents (16.67%)_2,9 By comparing the two groups regarding the mobility  status within 6 months post-operative, there  was no significant statistical difference  using Chi square.

Our results  were different  from  the results

reported  by  Ruckley  et  al.,  who  stated  that

64   (84%)   of  the   skew   and   50  (77%)   of the Burgess patients had been fitted with prostheses  (X2 = 0.78,p = 0.38) and 59 (78%) and 46 (71%), respectively were walking with or without  aid. These differences were not statistically  significant. This  difference was caused  due to the high  cost of the prosthesis in  Egypt  which   could  not  be  afforded   by the majority of our patients  and lack of availability of prosthesis in Saudi Arabia.

Among  the  25  patients  of  group  1, there

were   2  patients   with   infection   extending on the  posterior  aspect  of the  foreleg above the  ankle  joint,  to  a  level  that  makes  long posterior  flap  BKA  not  applicable, so  skew flap amputation was performed. One of these two  patients  had  primary  healing  within  the

7  days  postoperatively while  the  other  had

wound   discharge and  minor   edge   necrosis

within the 7 days postoperatively and healing was delayed  till the 19th day postoperatively. This was mentioned in Rutherford's vascular surgery 7th edition: the skew technique may be of particular benefit when there is inadequate skin  to create  a conventional long  posterior flap.lO Our study revealed  no significant statistical differences between the two groups regarding both  the  early  and  late  outcomes. The  skew  flap  technique is  considered the routine procedure for below knee amputation in many centers around  the world.

Conclusion:

The   skew   flap  technique  is  considered the  routine  procedure  for  below  knee amputation  in   many    centers    around   the world.  We conclude  that the skew flap is just as effective  as the  long  posterior flap. Skew flap is especially useful when  below knee amputation is indicated  and the posterior skin is  inadequate to  construct   a  long  posterior flap.

Reference:

1- Eidt L, Kalapatapu F: Lower extremity amputation; Techniques and Results (?ili ed.): Vascular    Surgery.   ELSEVIER,   Saunders,

2010.

2-    Ruckley    CV,   Stonebridge    PA,   Prescott RJ: Skew flap versus long posterior flap in below-knee  amputations: Multicenter trial. J Vase Surg 1991; 13: 423-427.

3-    Woodburn N, Ruckley M: Lower  extremity amputation;  technique  and peri-operative care.    In:    Vascular    Surgery.   Rutherford (6th   ed.):   ELSEVIER,   Saunders,   2005;

2460-2473.

4-    Cumming  JGR, Spence VA, Jain AS, et al: A below to above knee amputation  ratio of

2.5: 1, is the minimum  acceptable  standard

for units providing a lower limb amputation service.  Vascular Surgical Society, 1987, Newcastle.

5-  Robinson   KP:  Skew  flap  below-knee amputation. Ann R Call Surg Engl1991; 73:

155-157.

6-    Sajja  S:  Below-knee  amputation  operative techniques   in   General   Surgery   2005;   7:

82-89.

7-  Harrison JD, Southworth S, Callum KG: Experience with the 'skew flap' below-knee amputation. Br J Surg 1987; 74: 930-931.

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