Biomedical subjects

Axel Prokop

Publications and source records attributed to Axel Prokop.

8 recordsLinked to original sources

PubMed2007

Anatomy of the clavicle and the intramedullary nailing of midclavicular fractures.

Intramedullary fixation is used increasingly to treat clavicular fractures. Anatomical variations in the clavicle of relevance to this procedure are analyzed. The length, diameters and curvature of the clavicle were measured in 196 specimens from the dissecting room. The calcium bone density was analyzed in 300 cross-sectional samples of 100 specimens. The thickness of cortical and medullary bone of 70 slices was analyzed from freshly plastinated clavicles with implants in place. The female clavicle was shorter, less curved, and had a lower concentration of calcium than the male clavicle. Measurement of cortical thickness showed a mean value of 1.05 +/- 0.23 mm at the most sternal measuring point, 2.05 +/- 0.29 mm at the midpoint of the clavicle, and 0.95 +/- 0.35 mm at the acromial end. The thinnest regions were the medial ventral cortex and the dorsal acromial cortex. These measurements explain clinical observations on nail perforation. The diameter of the medullary canal measured 6.7 +/- 2.6 mm at its narrowest part, so that reaming (i.e., predrilling the medullary canal) prior to 3.5 mm titanium nail insertion is not necessary. The main difficulties encountered when placing a nail are secondary to the S-curvature of the clavicle. In 80% of fractures, the break is located at the narrowest diameter of the medullary canal. Thus, the clavicle displays definite gender- and side-specific anatomical features in terms of length, diameter, curvature, and calcium concentration. These should be considered when performing intramedullary fixation.

Adult↗

PubMed2006

Malunion of the clavicle causes significant glenoid malposition: a quantitative anatomic investigation.

OBJECTIVE: An experimental cadaver model was used to assess the effects of a malunited fracture of the middle third of the clavicle on the functional anatomy of the shoulder joint. METHOD: Anatomic samples were prepared with simulated shortening and axial malposition of the clavicle. From these, alterations in glenoid fossa position were measured and depicted graphically. RESULTS: Healing of clavicle fractures with bony shortening leads to a ventromedialcaudal shift in glenoid fossa position. The following malpositions of the clavicle lead to the respective glenoid fossa positional changes: caudal deviation leads to a mediocaudal shift, cranial deviation leads to a dorsolateral shift of the glenoid fossa, ventral deviation causes a ventrolateral shift, dorsal deviation leads to mediocaudal shift of the fossa, cranial rotation leads to ventrolateral shift in fossa position, and caudal rotation leads to a dorsomedial shift in glenoid fossa position. CONCLUSION: Clinical implication of these data is that bony shortening in combination with caudal displacement leads to distinct functional deficits in abduction, particularly overhead motion. Using the above data, a vector model was created to calculate position of the glenoid fossa dependent on clavicle position/malposition. The model is a valuable tool to be used for planning open reduction and fixation of clavicular fractures or malunions.

Clavicle↗

PubMed2005

Degradation of poly-L/DL-lactide versus TCP composite pins: a three-year animal study.

Biodegradable polylactide implants allow secure fixation of osteochondral fractures. This quasirandomized parallel-group animal study investigates whether a composite implant of poly-L/DL-lactide (PLDLLA) with additional 10% beta-tricalcium phosphate produces an osteoconductive effect, whether the admixture positively influences implant degradation (assessed by comparing time to implant degradation), and whether the pin sites of degraded implants are replaced with bone tissue. On 36 medial femoral condyles of sheep, osteotomies were fixed with either three PLDLLA pins or three composite pins. At 3, 18, and 36 months, the pin sites were measured histologically and the state of degradation assessed according to Pistner's classification. All fractures healed without clinically relevant complications and without displacement. Both pin types led to asymptomatic pin-site enlargement at 18 months, which disappeared by 36 months. At 18 months, 14 of 18 PLDLLA pins were no longer evident, whereas 16 of 18 composite pins showed only peripheral degradation. By 36 months, all implants from both groups were completely degraded and replaced with scar (2/18) or bone tissue (16/18). At 36 months there was no evidence for significant improvement of either degradation performance or osseointegration through use of the 10% TCP composite mixture.

Animals↗

PubMed2005

A comparative radiological assessment of polylactide pins over 3 years in vivo.

Biodegradable polylactide implants allow secure fixation of osteochondral fractures with minimal adverse effects. The goal of this prospective, randomized animal study was to show whether osteoconductive effects can be achieved through the development of poly-L/DL(70/30)lactide composite implants with 10% beta-tricalcium phosphate, and whether degradation can be positively influenced and adverse effects minimized using such implants. An additional goal was to clarify which radiological procedure is most suitable to observe the course of follow-up. Thirtysix medial femoral condyle osteotomies of sheep were fixed with either 3 poly-L/DL-lactide pins or 3 composite pins, and the pin canal widths were measured with conventional radiographs, with CT, MRI, and histologically after 3, 18, and 36 months. All fractures healed completely without displacement or clinically relevant complications. The pin canals dilated secondary to pin degradation at the 12th month, and then decreased in size later. At 36 months, the pins had microscopically disappeared, and the canals were filled with bone or scar tissue. There were no statistically significant differences between the pin-types. Poly-L/DL-lactide pins and composite C-pins are suitable for secure fixation of small osteochondral fractures. Osteoconductive effects of biocompatibility or osseous integration relating to composite development were not evident. Conventional radiography and computer tomography were suitable techniques for observation of pin canals. Due to frequently observed artifact, MRI was not suitable to observe the course of the implants.

Absorbable Implants↗

PubMed2005

Biodegradable implants for Pipkin fractures.

The current study was designed to clarify whether biodegradable poly-L/DL lactide pins provide an operative alternative for fixation of Pipkin fractures. Nine patients with Pipkin fractures (one with Pipkin Type I, one with Pipkin Type II, and seven with Pipkin Type IV fractures) were treated surgically between 1996 and 2002. In all patients, the femoral head fractures were fixed with biodegradable, 2.7-mm and 2.0-mm polylactide pins. Eight patients were followed up for an average of 54.2 months. One patient died before the final followup. Eight fractures healed uneventfully. In one patient, a persisting femoral head defect led to posttraumatic arthritis requiring insertion of a femoral endoprosthesis at 1 year. The average range of motion of the affected hips of all patients at followup was 109 degrees -0 degrees -0 degrees in flexion and extension. External and internal rotation averaged 37 degrees -0 degrees -29 degrees . One patient had Brooker Grade I heterotopic ossification develop, and another had a Grade II heterotopic develop. Merle d'Aubigne and Postel ratings showed two excellent and five satisfactory results (average score, 13.1). Adverse effects from the polylactide implants were not observed. Pipkin fractures can be fixed successfully with biodegradable polylactide pins.

Absorbable Implants↗

PubMed2005

Outcomes and complications of elastic stable intramedullary nailing for forearm fractures in children.

This prospective study investigated medium-term outcomes for 51 children treated from 1997 to 2001 for displaced diaphyseal forearm fractures with elastic stable intramedullary nailing. Forty-three patients included achieved excellent/good functional results at an average follow-up of 38 months. Four patients required open fracture-manipulation at surgery. Complications included eight cases of soft-tissue irritation at nail-insertion site (three required shortening procedures), two temporary radial nerve branch injuries, four minimal rotational mobility deficits, one 10 degrees elbow extension deficit after splinting, and five small keloid scars. All patients were pain-free, without limitations in activities for daily life or sport/play activities by 12 months after hardware removal. Elastic stable intramedullary nailing is appropriate therapy for these injuries.

Adolescent↗

PubMedDate not supplied

Biodegradable implants versus standard metal fixation for displaced radial head fractures. A prospective, randomized, multicenter study.

This multicenter, prospective, randomized study compares the use of biodegradable polylactide pins with standard metal mini-fragment implants for the treatment of displaced radial head fractures. It compares complication rates and clinical outcomes of both treatment methods. At 2 years, 135 (82%) of 164 patients were available for evaluation. Equivalence of treatment method was defined as a difference of 10% or less in the number of complication-free patients. Functional status was assessed by using the Broberg and Morrey Elbow Score and compared by an unpaired t test. Good or excellent clinical results were achieved by 92% (56/61) of the control patients and 96% (71/74) of the polylactide patients. The incidence of complication-free patients was 3.7% less in the polylactide group than in the control group. The 1-sided 95% confidence interval for the treatment difference between the 2 groups was more than -6.1%. Biodegradable polylactide pins have at least comparable outcomes as standard metal implants for the internal fixation of reconstructable displaced radial head fractures.

Absorbable Implants↗

PubMedDate not supplied

Augmentation of intraarticular calcaneal fractures with injectable calcium phosphate cement: densitometry, histology, and functional outcome of 18 patients.

Eighteen patients with intraarticular calcaneal fractures treated with open reduction and internal fixation and augmentation with an injectable carbonated apatite cement. Functional follow-up studies using the Zwipp Foot Score and densitometry were performed at 6-month intervals postoperatively. Histological samples of biopsies obtained at the time of hardware removal (6 months postoperatively) were also analyzed. The use of bone cement led to intermediate-term functional outcomes that were no better than those reported with conventional surgical procedures using bone graft. Patients demonstrated postoperative difficulties similar to those seen in other studies of this fracture, including pain, subtalar motion restrictions, peroneal impingement, and difficulties on uneven terrain and with toe- and heel-walking. However, compared to patients treated surgically without injectable carbonated apatite cement, full weight bearing on the affected extremity was regained at an average 4 weeks postoperatively. In addition, autogenous bone graft was not required to fill the osseous defect using this technique, minimizing morbidity and discomfort. During the present observation period of 3 years, only a slight decrease in the density of the peripheral zones of the cement block was observed. Histological examination revealed fibrous bone formation resulting from remodelling processes. Complete resorption and remodeling of the bone cement were not complete at 3 years. One patient developed a postoperative wound infection. Another displayed cement loosening secondary to failure of bony ingrowth.

Adult↗