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Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_IV | Pages 567 - 567
1 Oct 2010
Martin A Bale R Fischler S Haid C Von Strempel A
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Introduction: With non-fusion stabilization surgery technique, the demands on the pedicle screw system have increased. The screw implants require a high press fit for optimum bone integration and a high pullout strength to guarantee primary stability. We compared the cylindrical screw design from a pedicle screw system with the conical design in regard to the insertional torque and pullout strength.

Methods: Three human cadaver specimens L1 – L5 (15 vertebrae, 30 pedicles) were fitted with pedicle screws on both sides. The pedicles were randomized to one of two screw types: 1) cylindrical pedicle screw, 2) conical. A computer tomographic bone density measurement was performed beforehand. The insertional torque was measured while inserting the pedicle screws. The correct position of the screw was verified using computer tomography. In order to test the pullout strength, the preparations were divided up into individual vertebrae and fixed.

Results: The mean peak insertional torque for the conical screws was significantly higher than that for the cylindrical screws. The pullout strength showed no significant difference between the two types of pedicle screws. With both the conical and the cylindrical pedicle screws, the pullout strength and insertional torque significantly decreased with decreasing bone density in the preparations.

Conclusions: Statements in the literature about the effect on insertional torque and pullout strength of using a conical or cylindrical pedicle screw design vary. The two screw designs in our study only differed in regard to their internal diameter. The significantly higher insertional torque values found for the conical screws could describe the improved screw press-fit behavior. The pullout strength was not significantly affected by the conical design. No correlation was found between the insertional torque and pullout strength. In order to optimize the adjustment of insertional torque and pullout strength, we recommend the conical pedicle screw design for non-fusion surgical techniques for the surgical treatment of degenerative diseases of the lumbar spine.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_I | Pages 6 - 6
1 Mar 2005
Rajasekhar C Paul A Bale R Stringfellow H
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Liposarcoma is the most common soft tissue sarcoma accounting for 20% of all mesenchymal malignancies.We report a rare histological variant arising from the dorsum of the foot. A 55 year old lady presented with a slow growing, well defined swelling on the dorsum of the foot. Histological examination following complete excision showed a tumor with zones of dense collagenous tissue containing pleomorphic spindle cells and scattered atypical adipocytes. A diagnosis of spindle cell sarcoma was made and referred to the local Sarcoma unit. Repeat excision and histology confirmed margins free of tumor. Four years after primary excision, patient is well with no evidence of recurrence or metastasis.

Spindle cell liposarcoma is a rare variant of well differentiated liposarcoma characterized by prominent spindle cell component. Previously reported cases originated in the subcutaneous tissues of shoulder girdle and upper limb. Main differential diagnoses include benign lesions such as spindle cell lipoma, and diffuse neurofibroma as well as dermatofibrosarcoma pro-tuberans and other malignancies such as sclerosing liposarcoma, myxofibrosarcoma, malignant peripheral nerve sheath tumor and fibromyxoid sarcoma. Spindle cell Liposarcomas tend to recur locally and may dedifferentiate with a potential for metastasis. Wide excision and long term follow up looking for recurrence and metastasis is necesssary in these rare variants of liposarcoma especially those arising at atypical sites as in our case.


Orthopaedic Proceedings
Vol. 85-B, Issue SUPP_II | Pages 171 - 171
1 Feb 2003
Parsons S Helm A Maclaughlin E Bale R
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The aim of our study was to demonstrate the safety of the use of a maximal allowable blood loss formula to reduce the transfusion requirements of elective primary arthroplasty patients.

In the UK, many arthroplasties are performed each year. Many patients will receive blood transfusion post operatively. Often these patients don’t predonate blood, and most units don’t use re-infusion drains. Blood is both costly, and potentially hazardous product to use; we felt it may be beneficial to patients to reduce the unnecessary use of allogenic blood.

We began with a prospective six-month audit, of transfusion requirements of our elective primary arthroplasty patients, establishing our blood use. Our results showed that 66% (58% knees, 73% hips) had at least one unit of blood post operatively, averaging 1.3 units per patient (1.1 knees, 1.5 hips).

Following this, we instituted a new protocol for postoperative blood transfusion. The protocol involved calculation of a maximum allowable blood loss (MABL) the patient could safely lose prior to the need for blood transfusion. This value is based on the patients weight and preoperative haematocrit. Blood loses up to this value would be made up with colloid replacement. When this MABL value is reached the patient has a bedside measurement of their haematocrit. If it has fallen below 0.3 for males and 0.27 for female patients then they are transfused blood, one unit at a time until it is at or above these reference values. As a ‘safety net’ all patients have a formal full blood count on days 1,2, and 3, and are transfused if their Hb is less than 8.5 g/dl.

This protocol was in place for one year (Feb. 2001-Feb. 2002). Our results show, on average a reduction of blood use from 1.3 units to 0.56 units per patient. The percentage transfused was reduced from 66% to 24% (11% knees, 34% hips).

Overall we had a significant reduction of 59% in units of blood transfused to patients following the new protocol. And feel that this method demonstrates a safe system to reduce transfusion requirements.