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Mark J C Smeulders

Publications and source records attributed to Mark J C Smeulders.

11 recordsLinked to original sources
PubMed2006

Adaptation of the properties of spastic muscle with wrist extension deformity.

To show that human muscle may adapt to tendon transfer, adaptation of flexor carpi ulnaris (FCU) function was studied by measuring active and passive length-force characteristics at initial operation and at reoperation in a case of extension deformity secondary to FCU tendon transfer. At reoperation, FCU was 20 mm shorter; active force decreased approximately 10%, indicating atrophy; and passive force increased, reflecting increased stiffness. FCU fiber length was unchanged. The presented case shows that human forearm muscle may adapt to a transferred function.

Adaptation, Physiological↗
PubMed2006

Skin-sparing mastectomy and immediate breast reconstruction by use of implants: an assessment of risk factors for complications and cancer control in 120 patients.

BACKGROUND: Combined skin-sparing mastectomy and immediate reconstruction by use of an implant is increasingly accepted as a therapy for patients with breast cancer or a hereditary risk of breast cancer. Because little and contradictory evidence regarding possible risk factors for postoperative complications is available, the authors retrospectively assessed 13 such factors. They also evaluated the oncological safety of the procedure. METHODS: From July of 1996 through June of 2000, 174 skin-sparing mastectomies were combined with immediate breast reconstruction in 120 patients. The authors assessed the influence of five patient-related and eight breast-related characteristics on the incidence of a complicated postoperative course by univariate and multivariate analyses. Oncological safety was evaluated by observed recurrent disease and 5-year survival. RESULTS: Severe complications were observed in 17 patients of the 120 patients (14 percent), or 19 of the 174 breasts (11 percent). The patient-related characteristics of age and being operated on unilaterally significantly increased the risk of complications. Resident plastic surgeons and previous breast-conserving therapy including radiotherapy significantly increased the risk of implant loss. The local relapse rate among patients operated on for cancer was 0.02. The actuarial 5-year survival rate among patients who underwent curative mastectomies was 0.96. CONCLUSIONS: Combined skin-sparing mastectomy and immediate reconstruction by use of an implant is oncologically safe, but the risk of postoperative complications cannot be neglected. The authors' observations may offer guidance for adapting indication and treatment strategies for patients with breast cancer or increased hereditary risk of such cancer.

Adult↗
PubMed2005

Spastic muscle properties are affected by length changes of adjacent structures.

Recent animal experiments have shown that up to 37% of muscle force may be transmitted to adjacent structures rather than reach the insertion of the muscle's tendon, and that the extent of such force transmission depends on the length and relative position of these structures. We tested whether the force-length characteristics of the distally tenotomized human flexor carpi ulnaris muscle (FCU) of nine patients with cerebral palsy varied with the change of relative length of adjacent structures induced by a change of wrist position. In four patients, the FCU exerted up to 40% more active force in a flexed wrist position at short FCU length, whereas the active force was not significantly higher in the other five. In the same manner, passive force-length characteristics of the spastic FCU changed upon changes in wrist position. Variability in myofascial force transmission may partly explain the variability in success of the FCU-transfer.

Adolescent↗
PubMed2005

Reliable and feasible evaluation of linear scars by the Patient and Observer Scar Assessment Scale.

BACKGROUND: Although scar evaluation tools are necessary for an evidence-based approach to scar management, there is as yet no generally accepted tool. The Patient and Observer Scar Assessment Scale was developed recently and found to be a useful subjective evaluation tool for burn scars. The authors tested the Patient and Observer Scar Assessment Scale on linear scars, the largest category of surgical scars. METHODS: One hundred linear surgical scars were assessed by three independent observers using the observer scale to evaluate vascularity, pigmentation, thickness, relief, pliability, and surface area. The patients evaluated their scars simultaneously and 2 weeks later using the patient scale for the following parameters: pain, itching, color, stiffness, thickness, and relief. RESULTS: The internal consistency of the observer and patient scales was good (Cronbach's alpha = 0.86 and 0.90, respectively). The reliability of the observer scale was good for the total score (r = 0.96, p < 0.001) and separate items (r > 0.86, p < 0.001) for three observers. Even a single observer evaluated scars reliably with respect to the total score (r = 0.88, p < 0.001) and the items vascularity, pigmentation, thickness, and surface area (r > 0.70, p < 0.001). The patient's intraobserver reliability was good for the total score (r = 0.94, p < 0.001) and separate items (r > 0.89, p < 0.001). The coefficient of variation of the total score was 10.4 percent for the observer scale and 15.8 percent for the patient scale, indicating good agreement. CONCLUSIONS: The Patient and Observer Scar Assessment Scale is an appropriate subjective tool for the evaluation of linear scars.

Adolescent↗
PubMed2005

The truly distal lateral arm flap: rationale and risk factors of a microsurgical workhorse in 30 patients.

The forearm part of the extended lateral arm flap may be separately raised on the most distal septocutaneous perforator of the posterior collateral radial artery. This truly distal lateral arm flap shares most of the advantages of the radial forearm flap and is associated with less donor site morbidity. From April 2000 to March 2004, we used 30 such flaps as the fasciocutaneous free flap of choice, mostly for reconstructions in the head and neck region. The eventful postoperative course observed in 5 of these flaps motivated us to evaluate the rationale and risk factors of this procedure. We prospectively analyzed the influence on the incidence of partial or complete flap loss of 19 patient-related or procedure-related characteristics that may have acted as risk factors. None were found to be of statistical significance. We found the distal lateral arm flap to have a less robust vascular anatomy than the radial forearm flap, resulting in the need for advanced surgical expertise to raise and handle it. As we recognized the difficulty of this flap to be associated predominantly with this anatomy of its vascular pedicle, we now take a more liberal stand toward the possibility of intraoperative conversion to the use of a radial forearm flap.

Adult↗
PubMed2004

Overstretching of sarcomeres may not cause cerebral palsy muscle contracture.

To answer the question whether the muscle contracture in patients with cerebral palsy is caused by overstretching of in-series sarcomeres we studied the active and passive force-length relationship of the flexor carpi ulnaris muscle (FCU) in relation to its operating length range in 14 such patients with a flexion deformity of the wrist. Force-length relationship was measured intra-operatively using electrical stimulation, a force transducer, and a data-acquisition system. Muscle length was measured in maximally flexed and maximally extended position of the wrist. The spastic FCU was found to exert over 80% of its maximum active force at maximal extension of the wrist and this indicates abundant overlap of the sarcomeres. At maximal wrist extension, FCU passive force corresponded with only 0.7-18% of maximum active force. Both findings imply that the FCU sarcomeres are not overstretched when the wrist is extended. We conclude that the overstretching of in-series sarcomeres appears not to be the cause of contracture of the spastic FCU.

Adolescent↗
PubMed2004

Intraoperative measurement of force-length relationship of human forearm muscle.

The specific relationship between force and length is one of the most important characteristics of vertebrate muscle. The only accurate method to measure the force-length characteristics is to generate a set of isometric force-time plots at different muscle lengths. In humans, such force-length characteristics mostly are based on indirect measurements that have their limitations. A method of direct, in vivo measurement of force-length characteristics of the human flexor carpi ulnaris muscle using relatively simple equipment during transposition surgery is presented. The method is proven reproducible, with an overall estimated error of 2.8%.

Adolescent↗
PubMed2004

Verifying surgical results and risk factors of the lateral thoracodorsal flap.

In 1986, the combined use of the lateral thoracodorsal flap and an implant was introduced as an alternative method of delayed reconstruction of small to medium-size breasts for postmastectomy patients who are reluctant or unable to consider reconstruction by tissue expansion or by more extensive autologous tissue transplantation. So far, the technique has only been proven reproducible in Sweden. Postmastectomy radiotherapy has been proven to increase the risk of wound-healing complications after lateral thoracodorsal transplantation, and additional risk factors such as advanced age, obesity, smoking, and some general health characteristics have been indicated. The authors initiated a prospective study to assess the reproducibility of this technique outside Sweden and to confirm the proven risk factor, prove or refute the alleged ones, and possibly identify additional factors. Additionally, they applied the technique for immediate breast reconstruction and tried to expand the indications and applications of the lateral thoracodorsal flap even further. The authors report on their initial experience with 60 lateral thoracodorsal flaps and conclude that the use of this flap is a well-reproducible technique for breast reconstruction, with few complications leading to failure. Using the lateral thoracodorsal flap in combination with tissue expanders allows for reconstruction of breasts of larger than medium size. Moreover, the authors successfully applied fully deepithelialized lateral thoracodorsal flaps for additional indications. The statistical significance of postmastectomy radiotherapy as a risk factor could not be confirmed, but some general health characteristics were found to be significant patient-related risk factors. Out of five procedure-related characteristics, only increased flap length was proven to negatively influence the outcome of the procedure.

Adult↗
PubMed2002

Progressive surgical dissection for tendon transposition affects length-force characteristics of rat flexor carpi ulnaris muscle.

Extramuscular connective tissue and muscular fascia have been suggested to form a myo-fascial pathway for transmission of forces over a joint that is additional to the generally accepted myo-tendinous pathway. The consequences of myo-fascial force transmission for the outcome of conventional muscle tendon transfer surgery has not been studied as yet. To test the hypothesis that surgical dissection of a muscle will affect its length-force characteristics, a study was undertaken in adult male Wistar rats. During progressive dissection of the flexor carpi ulnaris muscle, isometric length-force characteristics were measured using maximal electrical stimulation of the ulnar nerve. After fasciotomy, muscle active force decreased by approximately 20%. Further dissection resulted in additional decline of muscle active force by another 40% at maximal dissection. The muscle length at which the muscle produced maximum active force increased by approximately 0.7 mm (i.e. 14% of the measured length range) after dissection. It is concluded that, in rats, the fascia surrounding the flexor carpi ulnaris muscle is a major determinant of muscle length-force characteristics.

Animals↗
PubMed2002

Motor control impairment of the contralateral wrist in patients with unilateral chronic wrist pain.

OBJECTIVE: Assessment of the quality of fine motor control in patients with unilateral chronic wrist pain seldom focuses on the possibility that control of movements is effector independent at the cerebral level. This mechanism may be involved in an impairment of motor function in the unaffected wrist. We studied the possible motor impairment in the unaffected wrist in patients with chronic wrist pain. DESIGN: Eighteen patients with chronic wrist pain in their dominant hand and 20 healthy controls performed, using their nondominant hand, back-and-forth, left-to-right stroke patterns with a pen on a digital writing tablet connected to a computer. Fluency of movement, defined as the number of zero-crossings of the acceleration curve (pZC), average stroke size, and average velocity were calculated. RESULTS: The controls moved significantly more fluently than the patients (pZC, 0.26+/-0.07 for controls and 0.46+/-0.20 for patients; P < 0.001), suggesting that long-term afferent disturbances may compromise cerebral motor control mechanisms. CONCLUSIONS: This result is in accordance with the view that chronic pain complaints may be maintained by persistently abnormal cerebral motor control. This finding opens a new perspective on the understanding and treatment of chronic wrist pain.

Adolescent↗