Pubovisceral muscle avulsion


  • DOI: 10.1111/j.1479-828X.2007.00814.x

The meticulous documentation of this case1 brings significant anatomical insights. It also begs some further questions, among which are: How exactly did the delivery dislocate the muscle insertion? How is this to be repaired?

There was no muscle tear. Its insertion was dislocated, and the muscle retracted laterally and dorsally. The patient concerned was left with no clinical disability. There were no abnormal symptoms. She did have a cystocoele and some degree of uterine prolapse.

With regard to pathogenesis. Was the head deflexed during labour? The transverse diameter of the midpelvis is no more than 12–13 cm. A deflexed head is 11.2 cm. There is not much space for passage of a deflexed head. Collagen depolymerises just before labour. The tensile strength of (cervical) collagen immediately after delivery is 7%, of that of the non-pregnant woman and the extensibility is increased by 50%.2 Muscle insertion points are collagenous. If they, too depolymerise, which is likely if they are to be pushed aside for delivery, they would be more easily dislocated. By the same token, such stretching would protect the muscle from tearing.

Surgical repair. I agree with the comments made by the authors1 that repair by conventional means is unlikely to be successful. In the mid-1980s, we developed a technique that used the negative qualities of foreign body reaction in a positive way. In our experimental animal studies, we found that a plastic (Mersilene) tape inserted retropubically formed a collagenous cylinder which attached to both muscle and pubic bone.3 This principle was subsequently applied to the cure of stress incontinence by constructing an artificial collagenous pubourethral neoligament. It was also recently applied to repair of cystocoele.4 On both sides, the tape was inserted medial to the vaginal wall, and brought to a position just medial to the obturator muscle insertions. Then it was tightened to maximal tension. We believe that we were tightening the laterally displaced aponeurotic sheet which is attached to the arcus tendineus fascia pelvis, and which is also attached to the pubovesical muscle. Clearly, this contention needs to be objectively determined.