Biomechanical modeling to prevent ischial pressure ulcers

With 300,000 paraplegic persons only in France, ischial pressure ulcers represent a major public health issue. They result from the buttocks? soft tissues compression by the bony prominences. Unfortunately, the current clinical techniques, with – in the best case – embedded pressure sensor mats, are insufficient to prevent them because most are due to high internal strains which can occur even with low pressures at the skin surface. Therefore, improving prevention requires using a biomechanical model to estimate internal strains from skin surface pressures. However, the buttocks? soft tissues? stiffness is still unknown. This paper provides a stiffness sensitivity analysis using a finite element model. Different layers with distinct Neo Hookean materials simulate the skin, fat and muscles. With Young moduli in the range [100–500 kPa], [25–35 kPa], and [80–140 kPa] for the skin, fat, and muscles, respectively, maximum internal strains reach realistic 50 to 60% values. The fat and muscle stiffnesses have an important influence on the strain variations, while skin stiffness is less influent. Simulating different sitting postures and changing the muscle thickness also result in a variation in the internal strains.     

Modified hamstring musculocutaneous flap for the coverage of ischial pressure sores.

Ischial pressure sores can be efficiently covered with a modification of the traditional V-Y advancement flap, the musculocutaneous hatchet flap. Results of operations performed on 10 patients prove its reliability.     

Complications of total ischiectomy for the treatment of ischial pressure sores

Five patients are reported, 4 of whom had total ischiectomies and the other an extensive partial ischiectomy. In each, recurrent ulcers, extending into the perineum, developed subsequently. One patient had a urethrocutaneous fistula as a result of his perineal ulcer, and he had to undergo an ileal loop diversion. Following a unilateral ischiectomy, the pressure is shifted to the opposite ischium, and this favors the development of another ischial pressure sore on the opposite side. After bilateral ischiectomy there is much more pressure on the perineum, and these patients may go on to develop a perineal pressure sore--particularly if there is a dislocated hip. Recurrent pressure sores which extend into the perineum are difficult to treat, and usually they appear to be related to a previous extensive removal of the ischia.     

An evidence-based approach to pressure sores

The Maintenance of Certification module series is designed to help the clinician structure his or her study in specific areas appropriate to his or her clinical practice. This article is prepared to accompany practice-based assessment of preoperative assessment, anesthesia, surgical treatment plan, perioperative management, and outcomes. In this format, the clinician is invited to compare his or her methods of patient assessment and treatment, outcomes, and complications, with authoritative, information-based references. This information base is then used for self-assessment and benchmarking in parts II and IV of the Maintenance of Certification process of the American Board of Plastic Surgery. This article is not intended to be an exhaustive treatise on the subject. Rather, it is designed to serve as a reference point for further in-depth study by review of the reference articles presented.     

Management of pressure sores in a specialty center. A reappraisal.

We report a study on the surgical management of 145 pressure sores in 115 patients treated in a spinal cord injury center. There is a definite trend toward better education of these patients, who do not develop their first pressure sores until years following the injury. When the patient comes in for an ulcer, he is usually healthy and the ulcer is small and clean. In such instances the ulcer can be excised and closed, preferably with a myocutaneous flap, and the patient can usually begin sitting by the 21st post-operative day. In the ideal setting he may be discharged to his home on a custom-fitted (for pressure) cushion within 4 to 5 weeks, without increasing the risk of recurrence. Prophylaxis for the future is, probably, the most essential part of the treatment.     

Treatment of ischial pressure ulcers with a posteromedial thigh fasciocutaneous flap.

This study describes the use of the posteromedial thigh fasciocutaneous flap for the treatment of ischial pressure sores. The authors prefer this flap because it is the fasciocutaneous flap nearest to the ischial region, it is easy to raise, and it causes no donor-site morbidity. In this study, 11 ischial pressure sores in 10 paraplegic patients were closed using the posteromedial thigh fasciocutaneous flaps. All flaps survived, although two caused distal necrosis; after these same two flaps were readvanced, they survived. After an average follow-up time of 77 months, seven of the 10 patients have had no recurrence of ulcers.This fasciocutaneous flap was previously described by Wang et al. However, this study revealed that the arrangement of the vascular pedicle was different from that described by Wang et al. To reveal the vascular supply of this flap, anatomic dissections were conducted. The source of circulation to this flap was the suprafascial vascular plexus, in addition to the musculocutaneous perforator. The dominant pedicle was the musculocutaneous perforator from either the adductor magnus muscle or the gracilis muscle. The key to safe elevation of this flap was the accurate outlining of the skin island directly over the vascular pedicle and the preservation of the proximal fascial continuity. Of the 11 flaps, two viability problems occurred. These partial flap losses resulted from the failure to properly include the perforator. It is the authors' conclusion that the width of the flap should be greater than 5 cm. In addition, it is safe to make a flap within a 1:3 base-to-length ratio in a fatty, diabetic patient. This posteromedial thigh fasciocutaneous flap was found to be a valuable alternative for reconstruction of primary or recurrent ischial pressure ulcers.     

Repair of ischial pressure ulcers with gracilis myocutaneous island flaps.

Ischial pressure sores can be repaired with gracilis myocutaneous island flaps, and this technique offers numerous advantages over the use of posterior thigh flaps. Several illustrative cases are described.     

Gluteus maximus myocutaneous flaps for repair of pressure sores.

Myocutaneous flaps based on the gluteus maximus muscle, and its blood supply, have many advantages for the surgical repair of pressure sores in paraplegics. These are described, as well as the techniques used in various areas.     

Prevention of pressure sores by identifying patients at risk.

The risk of pressure sores developing in patients admitted with acute conditions was assessed by a simple risk score system based on age, reduced mobility, incontinence, pronounced emaciation, redness over bony prominences, unconsciousness, dehydration, and paralysis in a prospective clinical study. During seven months in 1977, 600 of 3571 patients were classified as at risk. Of these 35 (5.8%) developed sores compared with five (0.2%) of those not at risk. The results of this study compared with those over the same period in 1976 show that close observation of at-risk patients and early detection of pressure sores prevents their development.     

Surgical reconstruction of pediatric pressure sores: long-term outcome.

The long-term outcome after the surgical repair of pressure sores in the adult population has been well studied. Recurrence rates from 25 to 80 percent have been reported, despite improvements in surgical repair and mechanical support devices. Such high recurrence rates have led many investigators to question the rationale for the surgical closure of pressure sores. There are no published long-term data that document pressure sore recurrence after surgical treatment in the pediatric population. A retrospective analysis of all patients who underwent surgical reconstruction of grade III and IV pressure sores at the Children's Hospital of Philadelphia from 1987 to 1999 was performed. During this 12-year period, 19 consecutive patients with a mean age of 16.2 years were operated on for 25 pressure sores. Follow-up was obtained for 15 patients (79 percent), who underwent repair for 20 pressure sores. Mean postoperative follow-up was 5.3 years (range, 11 months to 11 years). Mean age at the time of surgery was 16.5 years. The overall pressure sore recurrence rate was 5 percent (1 of 20 sores). Overall patient recurrence (previous patient who developed a new sore) was 20 percent (3 of 15 patients). In contrast to the recurrence rates reported for the surgical repair of pressure sores in the adult population, the recurrence rate of 5 percent in the pediatric population is significantly lower. This demonstrates that the surgical reconstruction of pressure sores in the pediatric patient can be successful and provide long-term skin integrity.     

Aetiology of pressure sores in patients with spinal cord injury.

One hundred consecutive patients admitted to the National Spinal Injuries Centre, Stoke Mandeville Hospital, with pressure sores were studied to assess the relative importance of factors known to predispose to the development of scores. Loss of feeling was critical, because patients were unable to appreciate pain when the sore was developing. Risk of developing a sore increased with age, but duration of the paralysis was of equal importance. After discharge from hospital the presence of a caring relative or friend was essential for survival. Many patients developed sores because of poor facilities at home or inappropriate advice from those who looked after them. An even more distressing factor was the number of patients who developed sores in hospital owing to inadequate nursing care. There are relatively few paralysed patients in the community, but the lessons learnt in this study may be applied to all patients with orthopaedic injuries and to geriatric patients with limited mobility. Nursing and medical staff must turn patients regularly and ensure that there is proper equipment to relieve pressure on the skin. Patients should not be allowed to sit in a chair if they develop a sacral or trochanteric sore. More effort should be directed towards the appropriate education of patients, their relatives, and all those who are concerned with their welfare.     

Carcinoma in chronic pressure sores: a fulminant disease process

Four cases of squamous cell carcinoma arising from chronic pressure sores in paraplegic and tetraplegic patients are presented and the literature reviewed. These pressure-sore carcinomas are characterized by a shorter latency period and a fulminant clinical course with a very high metastatic rate. Very aggressive treatment including even hemicorporectomy must be considered if a cure is to be achieved.