Gelatinolytic and collagenolytic activity in periprosthetic tissues from loose hip endoprostheses.

OBJECTIVE: To study the contribution of different members of the metalloproteinases (MMP) family in gelatinolytic and collagenolytic potential, namely dinitrophenyl-Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg (DNP-S) sensitive proteolytic activity, in loose total hip arthroplasty (THA) endoprostheses. METHODS: Periprosthetic tissues and fluid samples were collected from patients subjected to hip endoprosthesis replacement. DNP-S sensitive proteolytic activity was evaluated by the degradation of synthetic DNP-S and reverse phase high performance liquid chromatography, while gelatinolytic activity was assessed by gelatin zymography. The isolation and separation of gelatinases was performed by gelatin- and concanavalin A-Sepharose affinity chromatographies and the identification of collagenases by immunoblot analysis. RESULTS: High gelatinolytic activity was observed in all periprosthetic tissue extracts and fluid samples. All samples also exhibited DNP-S degrading activity, without pretreatment by activating agents. Upon fractionation of MMP by gelatin-Sepharose affinity chromatography it was found that the gelatin-unbound collagenases are exclusively responsible for DNP-S degrading activity. Activated species of both MMP-1 and 13 were detected in most samples, but not the soluble form of MT1-MMP. Separation of gelatinases from each other and treatment with 4-aminophenylmercuric acetate (APMA) revealed that both enzymes mainly existed in complex with tissue inhibitor of metalloproteinase (TIMP). CONCLUSION: MMP-1 and MMP-13, which exist in activated form, could be responsible for the DNP-S-degrading activity in periprosthetic tissues and fluids, while the gelatinases do not contribute in this potential, since they mainly exist in complex with TIMP. The 2 collagenases may play a key role in the loosening of THA endoprostheses.

Extraoral vs. intraoral distraction osteogenesis in the treatment of hemifacial microsomia.

During hemifacial microsomia (HMF), an important phase of the treatment is elongation of the hypoplastic mandible, mainly the ramus, at an early stage. Twenty-two patients with HFM were treated with distraction osteogenesis: 12 with an extraoral device (10 unidirectional and 2 multidirectional) and 10 with an intraoral device. The mean elongation with the extraoral device was 21 mm, and with the intraoral device was 17 mm, resulting in a more symmetrical facial appearance. The advantages and disadvantages of both methods are presented, based on the authors' experience and a review of the literature. The extraoral device permits elongation of a greater distance, enables extraoral control of the vector of elongation, and conserves the gonial angle by working in many directions. The main disadvantages of the extraoral device are the social inconvenience to the patient and the extraoral cutaneous scars. Conversely, the intraoral device is much more socially convenient to the patient and avoids residual scarring. However, in 2 patients treated with an intraoral device, an undesired contralateral open bite appeared as a result of reduced vector control. The intraoral method should always be considered first because of its previously mentioned advantages. However, in severely hypoplastic patients, when three-dimensional correction and gonial angle control are necessary, or when there is a limited space along the planned distracted bone, the extraoral device has an advantage over the intraoral device.