25th November 2011, Volume 124 Number 1346

Hamesh Jina, Jeremy Simcock

A median sternotomy wound is invariably formed following coronary artery bypass surgery (CABG) or heart valve replacement surgery (HVR). The scar typically takes 18 months to mature and represents the end-point of tissue repair. A hypertrophic scar is persistently red, raised and sometimes itchy.1Presternal wounds have been reported2 to often scar poorly resulting in hypertrophic scar formation in comparison with scars formed in other anatomical locations.

Hypertrophic scarring can affect people aesthetically, symptomatically and psychologically. The purpose of this study is to evaluate scar formation following median sternotomy wounds using validated scoring tools.

Current wound management at Christchurch Hospital following CABG or HVR surgery is to apply a silver-based wound dressing for five days while the patient remains an inpatient. At discharge, the dressing is removed and an occlusive spray dressing is applied to the wound. No further dressings are applied in the community and no wound-care/scar management advice is given. Patients are followed up at six weeks post-surgery for clinical review.

In our study, we hypothesise that median sternotomy scars will scar poorly in general and in comparison with scarring from other sites (Bacillus Calmette-Guerin [BCG] vaccinations, open appendicectomy scars and ear piercings).

Methods

We examined the mature scar in patients who had median sternotomy scars from surgery 2 to 4 years previously. A database of patients existed who had CABG or HVR surgery during these years and every fifth patient was contacted and invited to participate in the trial. Invitations were sent until the study achieved 50 participants (20% of the eligible patient population). Exclusion criteria included those patients outside the Christchurch region. The patients were contacted by mail and telephone.
Sternotomy scars were assessed using the Manchester Scar Scale (MSS)3 and the Patient and Observer Scar Assessment Scale (POSAS).4 The MSS was used for the clinician evaluation of linear scars. This is a discontinuous scale which analyses the colour, contour, texture, margins and size of the scar. Part of the MSS includes assessment of control scars from other sites listed above. The POSAS is both patient and clinician-based using a continuous scale. The patient scale analyses variables such as pain, itch, colour, thickness and scar irregularity. These scar scales were used because they are reliable and valid measures of linear scarring.5,6
Patients also had their scars photographed. The same clinician scored all of the scars to eliminate interobserver differences.

Results

From a total of 84 patients who were invited to participate in this study we obtained our sample of 50 patients (response rate of 60%). Participants attended both a 15-minute outpatient consultation and photography under studio conditions. Baseline demographics were obtained as part of the MSS and shown in Table 1.

Table 1. Patient demographics
Gender
36 Males (72%)
14 Female (28%)
Ethnicity
47 White (94%)
2 Maori (4%)
1 Indian (2%)
Smoking status
15 Never (30%)
34 Ex (68%)
1 Current (2%)
Age (mean)
65.9 years
Diabetes
9 Patients (18%)

We found that patients report low rates of concerns about their scar. The most common complaints were pruritis in seven patients (14%), paraesthesia in three patients (6%) and one patient (2%) who experienced pain. Postoperative complications were noted in two patients (4%) with both patients having infection and one patient having wound dehiscence.

Patients were generally happy with the cosmesis of their scar with only three patients (6%) expressing concern.

Figure 1 demonstrates the variation in scarring within this patient group.

Figure 1. Images below demonstrate the difference in median sternotomy resultant scar

c

c

Sternotomy scar in a 65-year-old male with minimal scar formation. This was graded with a MSS of 9/20 and POSAS of 11/60
Sternotomy scar in a 54-year-old female with hypertrophic scar formation. This was graded with a MSS of 17/20 and a POSAS of 42/60

Total MMS scores ranged from 9–18 (maximum possible score of 20 for the worst scars) with a mean of 11.88. The highest score from a non-controllable variable was the colour of the scar at 2.18. Five patients (10%) had hypertrophic scarring with an overall average of 2.02. The sternotomy scar was also compared with scarring from previous BCG vaccination, appendectomy and piercing(s) and found to have a consistently higher score. These historic control scars scored from 7–13 with an average of 9.26. The appendicectomy scars were demonstrated in 24% of patients and accounted for 65% of all control scars. The overall MMS score for the open appendicectomy scar was 8.41 (7–10) which is 42% less than the sternotomy scar score.

The patient component of the POSAS ranged from 6–33 (maximum possible score of 60 for the worst scars) with a mean of 13.52. The highest score was colour (mean of 3.66). Pain and itch are two symptoms that patients did not score highly with average scores of 1.18 and 1.26 respectively. The clinician scale scores vascularisation, pigmentation, thickness, relief and pliability.

The total clinician scores ranged from 5–32 (maximum of 60) with an average of 16.08. The highest scored variable was relief at 4.22 followed by pigment at 3.58. All values from the MSS and POSAS can be seen in Table 2.

Table 2a–c. MSS and POSAS results

(a)
MSS
Average (range)
Size (maximum score 3)
Colour (4)
Contour (4)
Texture (4)
Matte/Shiny (2) 
Margins (2) 
Number (2)
3 (3)
2.18 (1–4)
1.98 (1–4)
1.74 (1–4)
1.04 (1–2)
1 (1)
1 (1)

(b)

POSAS – Observer
Average (range)
Relief (maximum score 10)
Pigmentation (10)
Pliability (10)
Thickness (10)
Vascularisation (10)
4.22 (1–7)
3.58 (1–7)
2.86 (1–6)
2.26 (1–8)
2.24 (1–6)
(c)
POSAS – Patient
Average (range)
Colour (maximum score 10)
Thickness (10)
Irregularity (10)
Stiffness (10)
Itch (10)
Pain (10)
3.66 (1–10)
3.18 (1–10)
2.9 (1–10)
1.32 (1–4)
1.26 (1–4)
1.18 (1–5)
MSS=Manchester Scar Scale; POSAS=Patient and Observer Scar Assessment Scale.

Discussion

Hypertrophic scarring has a number of causes including genetic factors, increased wound tension, delayed wound healing or location of the scar. In our study, the only identifiable cause of hypertrophic scar formation was the anatomical location. We found that the few patients who had postoperative complications did not have higher overall scores and patient demographics were not predictive for poor scarring.

These results support our hypothesis that hypertrophic scar formation in median sternotomy wounds is a relatively frequent occurrence compared with scarring from other sites. In our predominantly Caucasian population, where scars were at least 2 years old (compared with other studies which have analysed scars of variable ages), we found a low but significant rate of scar problems. Specifically, we found that 22% of patients were symptomatic or noticed poor scarring and 10% of patients were assessed by the clinician as having hypertrophic scarring from the median sternotomy wound.

No patients who had appendicectomy scars were symptomatic or demonstrated hypertrophic scars. The scoring from the scars formed from the appendicectomy wound were lower than that of the median sternotomy wound which is a useful comparator given that both scars evolve from wounds formed in a controlled environment.

Truong et al7 reviewed linear scarring in breast/chest wall and axillary wounds in women following breast surgery and, although different scoring tools were used, the scarring was poorer in breast/chest wall scars compared with axillary scars. This supports a predisposition to poorer scar formation across the chest wall rather than other regions.

It is clear from recent studies that ethnicity is a relevant factor in reported frequency of hypertrophic scar formation. Sproat found that the reported frequency of hypertrophic scar formation from median sternotomy scarring was 30% in Caucasian and 50% in Asian populations.8

Another recent paper looked at modifying the natural history of hypertrophic scar formation by utilising a topical silicone sheet in a population from Malaysia.9 In this study the patients were of Malay, Chinese and Indian origin. The authors found a 94% rate of hypertrophic scarring overall, of which the majority were in the control group. Because of the different ethnic origin, and therefore skin type, of patients in this study the results cannot be generalised to our population.

In our study, the MSS and POSAS evaluated similar scar features and produced similar results. Patient self-evaluation of the scar was generally less critical than that of the clinician. It is interesting that in this population the predominant area of concern from the patients perspective was pruritis rather than poor appearance. This may be attributed to lower expectation and less overall concern about cosmesis with more interest in the functional benefit of the surgery, especially in this group of older males. It also demonstrates the importance of evaluating scars with a scoring tool which takes patient symptoms into consideration. This explains why the Vancouver Scar Scale has not shown correlation with patient scar satisfaction following breast surgery.10

Many authors feel scar management is best approached by prevention rather than treatment. Prevention refers to intervention that alters the natural history of scar maturation to minimise the chance of developing problematic scarring. Treatment occurs when the scar has transgressed to a hypertrophic or keloid scar. The consensus from the International Consensus on Scar Management3 is that optimal treatment is managing the hypertrophic or keloid scar when the scar is immature but has an intact epithelium.

In summary, the majority of patients in our population have good median sternotomy scar scores. However, by using clinically relevant tools including patient symptoms, we have identified that at least one in five patients have a problematic scar and one in ten patients have hypertrophic scars. We found no patient factors which predict scar outcome and would recommend that all patients be offered preventative scar management

Summary

Our study examined scarring from wounds over the breast bone following cardiac surgery 2-3 years after their operation. We found that 20% of patients had complaints about their scar and 10% of patients were noted by the plastics doctor to have a prominent scar. We could not find any reason to why some patients had symptoms or scarred poorly. We feel that this group of patients would benefit from treatment to prevent bad scarring.

Author Information

Hamesh Jina, Surgical Registrar; Jeremy Simcock, Consultant Plastic Surgeon; Department of Plastic Surgery, Christchurch Hospital, Christchurch

Correspondence

Hamesh Jina, Surgical Registrar, Department of Plastic Surgery, Christchurch Hospital, PO Box 4345, Christchurch, New Zealand. Fax: +64 (0)3 3640157

Correspondence Email

hameshjina@gmail.com

Competing Interests

None.

References

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