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Biomedical subjects

P F Heini

Publications and source records attributed to P F Heini.

15 recordsLinked to original sources
PubMed2004

[Vertebroplasty in severe osteoporosis. Technique and experience with multi-segment injection].

In severe osteoporosis progressive collapse of multiple vertebrae is an unsolved problem. Medical treatment appears to be too slow to prevent the course. The evolving experience with vertebroplasty led us to treat these problems with more extensive cement injections. Of 362 patients who were treated with percutaneous cement injection over a 5-year period, 100 were injected at five and more levels (average 7.3, maximum 14). The surgical technique has been refined, allowing six levels to be injected monolaterally under local anesthesia. No more than six levels or 25-30 cc of cement should be injected per session. The outcome of the procedure is favorable in 84% of patients with a significant pain decrease (from 7.6 to 2.7 VAS). More impressive is the subjective report of the patients about better posture and increased force in their back, allowing them to become more active again. The radiological follow-up for 1 year shows a stable situation without further sintering of the reinforced vertebrae and maintained disc space in between these vertebrae. Vertebroplasty on multiple levels is efficient and can prevent further collapse. Due the risk of fat embolism the injections should be limited to six levels per session.

Adult↗
PubMed2002

[Percutaneous cementing techniques in treatment of osteoporotic spinal sintering].

During the last years minimal-invasive augmentation techniques of vertebral bodies have been established to stabilize painful height losses. A vertebroplasty fills the vertebral body with cement, whereas a kyphoplasty intends to achieve a reduction of kyphosis prior to cementing. The present review describes both techniques and summarizes in vivo and in vitro experiences.

Bone Cements↗
PubMed2002

Adjacent vertebral failure after vertebroplasty. A biomechanical investigation.

Vertebroplasty, which is the percutaneous injection of bone cement into vertebral bodies has recently been used to treat painful osteoporotic compression fractures. Early clinical results have been encouraging, but very little is known about the consequences of augmentation with cement for the adjacent, non-augmented level. We therefore measured the overall failure, strength and structural stiffness of paired osteoporotic two-vertebra functional spine units (FSUs). One FSU of each pair was augmented with polymethylmethacrylate bone cement in the caudal vertebra, while the other served as an untreated control. Compared with the controls, the ultimate failure load for FSUs treated by injection of cement was lower. The geometric mean treated/untreated ratio of failure load was 0.81, with 95% confidence limits from 0.70 to 0.92, (p < 0.01). There was no significant difference in overall FSU stiffness. For treated FSUs, there was a trend towards lower failure loads with increased filling with cement (r2 = 0.262, p = 0.13). The current practice of maximum filling with cement to restore the stiffness and strength of a vertebral body may provoke fractures in adjacent, non-augmented vertebrae. Further investigation is required to determine an optimal protocol for augmentation.

Biomechanical Phenomena↗
PubMed2001

Augmentation of mechanical properties in osteoporotic vertebral bones--a biomechanical investigation of vertebroplasty efficacy with different bone cements.

Recent clinical trials have reported favorable early results for transpedicular vertebral cement reinforcement of osteoporotic vertebral insufficiencies. There is, however, a lack of basic data on the application, safety and biomechanical efficacy of materials such as polymethyl-methacrylate (PMMA) and calciumphospate (CaP) cements. The present study analyzed 33 vertebral pairs from five human cadaver spines. Thirty-nine vertebrae were osteoporotic (bone mineral density < 0.75 g/cm2), 27 showed nearly normal values. The cranial vertebra of each pair was augmented with either PMMA (Palacos E-Flow) or experimental brushite cement (EBC), with the caudal vertebra as a control. PMMA and EBC were easy to inject, and vertebral fillings of 20-50% were achieved. The maximal possible filling was inversely correlated to the bone mineral density (BMD) values. Cement extrusion into the spinal canal was observed in 12% of cases. All specimens were subjected to axial compression tests in a displacement-controlled mode. From load-displacement curves, the stiffness, S, and the maximal force before failure, Fmax, were determined. Compared with the native control vertebrae, a statistically significant increase in vertebral stiffness and Fmax was observed by the augmentation. With PMMA the stiffness increased by 174% (P = 0.018) and Fmax by 195% (P = 0.001); the corresponding augmentation with EBC was 120% (P = 0.03) and 113% (P = 0.002). The lower the initial BMD, the more pronounced was the augmentation effect. Both PMMA and EBC augmentation reliably and significantly raised the stiffness and maximal tolerable force until failure in osteoporotic vertebral bodies. In non-porotic specimens, no significant increase was achieved.

Aged↗
PubMed2001

Bone substitutes in vertebroplasty.

Vertebroplasty--percutaneous cement augmentation of vertebral bodies--is an efficient procedure for the treatment of painful vertebral fractures in osteoporosis. At the present time, polymethylmethacrylate (PMMA) is the only available cement with reports of clinical application and experience. The material is easy to handle, the radiopacity can be adapted by adding contrast dye, and it is mechanically efficient. Composite cements (acrylic cements in conjunction with ceramics) are bioactive, highly radiopaque, and feature excellent mechanical properties. One such cement, Cortoss, is currently undergoing clinical trials for vertebroplasty and has so far been shown to be a potentially valuable alternative to PMMA. Several in vitro studies with injectable calcium phosphate (CaP) cements show their feasibility and mechanical effectiveness. Animal studies confirm their biocompatibility and osteoconductivity. However, handling problems and the limited radiopacity of these cements currently preclude their clinical use.

Animals↗
PubMed2001

Accuracy of computer-guided screw fixation of the sacroiliac joint.

Computer-assisted image guidance allows precise preoperative planning and intraoperative localization of surgical instruments. The technique recently was validated for the insertion of pedicle screws. In the laboratory, the precision of a surface-matching algorithm was evaluated for registration and accuracy and safety of screw placement into the vertebral bodies of S1 and S2 for fixation of the sacroiliac joint. Using six plastic pelves, 24 screw holes were made through the sacroiliac joint into the vertebral body of S1, and 12 holes were made through the sacroiliac joint into S2. The accuracy of the hole position was evaluated using a postoperative computed tomography examination. The safety factor was assessed by analysis of the remaining bone stock around the holes calculating a theoretical cylindrical volume being outside bone with increasing bore hole diameters. The registration was accurate with a mean error less than 1.4 mm in the posterior parts of the pelvis. The drilling followed precisely the preoperatively planned trajectories; perforation of the cortex of the sacrum was not observed. The safety factor of the S1 vertebral body is higher than that of S2 allowing larger diameter screw insertion into S1. This technique provides a safe and precise guide for transcutaneous or open insertion of iliosacral screws in cases of iliosacral dislocation or sacral fracture.

Algorithms↗
PubMed2000

Percutaneous transpedicular vertebroplasty with PMMA: operative technique and early results. A prospective study for the treatment of osteoporotic compression fractures.

Vertebroplasty-percutaneous cement augmentation of osteoporotic vertebrae is an efficient procedure for the treatment of painful vertebral fractures. From a prospectively monitored series of 70 patients with 193 augmented vertebrae for osteoporotic and metastatic lesions, we analysed a group of 17 patients suffering from back pain due to osteoporotic fractures. The reinforcement of 45 vertebral bodies in these patients led to a significant and lasting pain reduction (P < 0.01 ). The presented technique is useful, as, in one session, at least four injections can be performed when required, allowing the prophylactic reinforcement of adjacent vertebrae as well. The use of a low-viscosity polymethyl methacrylate (PMMA) in combination with a non-ionic liquid contrast dye provides a reliable and safe procedure. Extraosseous cement leakage was seen in 20% of the interventions; however, none of them had clinical sequelae.

Aged↗
PubMed2000

[What must the family practitioner know about spinal injuries].

Spine injuries in a general practitioner's environment are mainly related to osteoporosis fractures in the elderly as well as cervical spine injuries in the elderly especially fractures of the odontoid process that need to be excluded if there is any suspicion. For osteoporotic spine fractures the invention of vertebroplasty offers a new treatment option and therefore patients should be transferred to a spine surgeon for further evaluation. The fracture of the odontoid process can end up in a non-union problem if not treated early; therefore this injury must be excluded in patients after sustaining any head contusion and complaints of neck pain afterwards.

Emergencies↗
PubMed1998

Laparoscopic assisted spine surgery.

BACKGROUND: Evaluation of the technical aspects and clinical outcome of laparoscopic assisted interbody fusion (LAIF) using the BAK technique. METHOD: 17 patients with chronic low back pain due to degenerative disc disease at L5-S1 and L4-L5 were treated with LAIF using the BAK technique. Surgical time, blood loss and intraoperative problems were assessed. The short-term clinical and radiological outcome was measured. RESULTS: The technical part of the procedure depends on a learning curve. However, in collaboration with a laparoscopic surgeon no complications related to the technique occurred. The limits of the technique are due to the anatomical situation at the L4-L5 level. 14/17 patients had an improvement in their lower back pain. CONCLUSION: The technique of LAIF is demanding. The L5-S1 level can be addressed with ease; however, transabdominal fusion of L4-L5 is not recommended. Patient selection remains the keystone. LAIF is the least invasive measure in order to stabilize and fuse a motion segment.

Humans↗
PubMed1998

[Orthopedic aspects of vertebral metastases].

The palliative operative treatment for untractable backache due to spinal instability with/without (impendig) neurological deficit in patients with metastatic spine tumor is effective. The aim of treatment consists in improving the quality of live. An operative treatment is justified even in an advanced stage of the disease. The standard operative procedure consists in a posterior stabilisation combined with a decompression and debulking of the tumor.

Aged↗
PubMed1996

The pelvic C-clamp for the emergency treatment of unstable pelvic ring injuries. A report on clinical experience of 30 cases.

An unstable pelvic ring injury was stabilized with the AO C-clamp in thirty multiply injured patients. The average ISS was 29 (19-57). Transfusions totalled 24 units of blood/fresh frozen plasma/platelets (0-117) on average. In 12 cases, the application was for an unstable fracture alone, in 18 patients there was an unstable haemodynamic situation in addition. The application was haemodynamically effective in 10 cases. In 66% of cases, the initial reduction was good and the anatomy of the pelvic ring was adequately restored. Ten patients (33%) died; five during the first hours after admission due to haemorrhagic shock; the remaining five from multiple organ failure, fat embolism and head injury. Definitive stabilization was accomplished after 4.5 days on average (0-15). Complications relating directly to the clamp did not occur. The application of the C-clamp has a clear place in the management of polytraumatized patients with linear unstable pelvic ring injuries.

Adolescent↗
PubMed1994

Anterolateral subluxation of the talus after overlooked dislocation of the tibialis posterior tendon.

We report a case of tibialis posterior tendon dislocation into the disrupted ankle mortise between the tibia and fibula that was overlooked in the initial operative treatment of a fracture dislocation of the ankle with syndesmosis disruption. Recurrent widening of the ankle mortise prompted revision surgery where the posterior tibialis tendon dislocation was discovered to be the cause of secondary joint subluxation. The course of the tendon was corrected and the anatomy of the joint restored. One year after revision there is a good clinical result, however early posttraumatic osteoarthritis of the tibiotalar joint is seen radiologically.

Adult↗