Bacterial infection of bone may result in bone destruction which is difficult to cure due to poor accessibility to bone of systemically-administrated antibiotic and poor performance of currently available local antibacterial treatments. PolyPid Ltd developed a novel local drug delivery system based on self-assembly of pharmaceutically approved lipids and polymers that encapsulate doxycycline (Doxy). The formulation is self-assembled lipid matrix via the interaction of the lipids (cholesterol and synthetic phospholipids) and biocompatible - biodegradable polymer (poly-lactic-co-glycolic).

The entrapped Doxy is located within the anhydrous environment and therefore fully protected from both enzymatic and long-term water-exposure-related degradation. The fine coating of the tri-calcium phosphate (TCP) bone filler by this Doxy-containing formulation (BonyPid™) is capable of releasing intact and active drug at zero-order kinetics for a predetermined period of up to 30 days. The coating of the TCP granules with the polymer-lipids-Doxy formula (BonyPid™) did not change the granules’ macroscopic shape, but altered its color from white to pale yellow, which resemble the color of the entrapped Doxy. The average sizes of the non-coated TCP granules and the coated granules BonyPid™ were similar, as determined by measuring the widest dimension of each granule (1135±241 µm and 1072±242 µm, respectively, P=0.16). The MIC for Doxy that was released from BonyPid™ at different time points was similar to the non-encapsulated Doxy, suggesting full bioavailability of the released drug. BonyPid™ formulation structure was characterised by different physical methods including wide angle X-ray analyses (WAXS), differential scanning calorimetric (DSC) and SEM. WAXS analyses of BonyPid™ samples show a strong signal in the range of 1.3–1.8 2θ°, suggesting that the polymer and lipid TCP coating is a highly organised nano-substructure.

The principle lipid in BonyPid™ formulation is phosphatidylcholine, which constitutes more than 85% of the overall lipid mass. It was found that the length of the acyl chains (14, 16 and 18 carbons, respectively) can significantly alter the release rate of Doxy during the prolonged (30 days), zero-order release phase, but did not alter the release profile. The anti-infection activity of BonyPid™ was tested in the rabbit tibia model contaminated with 5×10⁵S. aureus. Both acute and chronic infection models were tested. Only BonyPid™ treatment demonstrated a statistically significant reduced bone absorption over the infected group (P<0.04 for day 7, 14 and 21) and significantly lower bacterial bone concentration (p>0.05) on day 21 following the bone grafting and the bacterial inoculation. In addition it was found that BonyPid™ did not reduce the osteo-conductivity as compared to non-coated TCP bone-filler. The first-in-man study for the treatment of contaminated / infected severe open long-bone fractures of BonyPid™ completed its 6 months follow-up. The results demonstrated high safety profile and significant efficacy; early bone callus formation and 0% infections in the BonyPid™ target bone fracture.

Purpose

Gustilo type III open fractures are associated with high infection rates in spite of instituting a standard of care (SOC) consisting of intravenous antibiotics, irrigation and debridement (I&D), and delayed wound closure. Locally-delivered antibiotic has been proven to assist in reducing infection in open fractures. The aims of this study are to determine the effectiveness and safety of a new implantable and biodegradable antibacterial product¹ in preventing bacterial infections and initiating bone growth in open fractures.

Several hundred Joint Replacement Surgeries have been done by surgeons (Gustilo/Leagogo) of the Philippine Orthopedic Institute in the Philippines since its inception over 20 years ago. Revision surgery of failed cemented hip replacement, have been increasing in the last decade, which is the subject of this report. The average total cost of revision hip surgery in the Philippines ranges from PEP 800 000 to PEP 1 000 000 or USD 20 000 to USD 25 000.

All medical records of the patients were reviewed to determine the following:

Etiology

A total of sixty nine (69) patients were included in the study. Sixty eight percent (68%) of the patients (47 out of 69) underwent revision due to aseptic loosening of components (femoral or acetabular). Nine (9) patients (13%) developed infection. Six (6) patients (9%) developed protrusio acetabuli that necessitated revision. Peri-prosthetic fracture was noted in four (4) patients (6%). Three (3) patients had hip dislocation (4%) prior to revision. Average number of years from index surgery is 9 years (2–18years).

Fifty nine (59) patients (86%) underwent cemented total hip prior to revision while ten (10) patients (14%) underwent cemented partial hip replacement prior to revision. Fifty six (56) patients (81%) have shortening on the affected side with an average of 3cm (1–6cm). Forty five (45) patients (65%) had proximal femoral bone loss requiring structural allograft. Thirty one (31) patients (45%) had acetabular defect (Paprosky Types I & II).

In sixty five (65) patients (94%), Active LockTM Cementless Hip Revision System was used. All patients were allowed full weight-bearing after revision surgery. Four patients (6%) developed acute post-op infection. Two patients (3%) had dislocation after revision surgery. At short-term follow-up of one year or more, only 5 patients were ambulating with assistive device. The rest are ambulatory, without aid and are symptom free.

Follow-up radiographs showed implants in excellent alignment, no signs of loosening, migration or subsidence.

The main reason for revision hip arthroplasty in the Philippines is aseptic loosening (68%) followed by infection (13 %). The use of long non-cemented, calcar-replacing curved revision stem, and strut allograft on the femoral side; jumbo, cementless acetabular socket and a high hip center on the acetabular side, addressed the problem of anatomic pathologies as a result of failed, cemented THR. There is no association between cause for revision with gender and age of the patients.

Introduction: The balance between achieving stable fixation and maintaining hand and wrist function during the treatment of distal radius fractures has continuously plagued the orthopaedic surgeon. A radio-radial external fixation system was developed by Dr. Guillermo Bruchmann to address these concerns. This study was designed to evaluate the immediate functional and anatomical results of the fixation system on intra-articular and extra-articular fractures. This is the first study documenting the use of this technique in Asia.

Materials and methods: Fifty-four consecutive patients, 18 male and 36 female, with 56 distal radius fractures were treated with closed reduction and application of the COBRA radio-radial external fixator. The operative procedure is described in detail. Immediate use of the affected hand for activities of daily living (ADL’s) was encouraged. Each patient was evaluated regarding functional and anatomical recovery at 2, 4 and 6 weeks postoperatively. Using the modified system of Green and O’Brien, functional recovery was based on the presence of pain, ability to do ADL’s, and range of motion. The grading system of Sarmiento was used to evaluate the overall maintenance of anatomic reduction by comparing the post-operative radiographs with those taken at 2, 4 and 6 weeks and on removal of the fixator.

Results: Assessment of functional status showed that patients had occasional to no pain at the pin sites at 2 weeks; improving on biweekly follow-up. Those with extra-articular fractures were able to do restricted ADL’s wearing the device within the 1st 2 weeks; with wrist motion arc between 50–75°. Patients with intra-articular fractures were functionally delayed by 2 weeks but with a dramatic improvement at 3–4 weeks, doing light ADL’s with wrist motion between 20–60°; progressively improving on follow-up. Biweekly radiographic evaluation showed good to excellent maintenance of reduction for both intra- and extra-articular fractures up to time of fixator removal. Average time of fixation was 7 weeks (range, 6 – 9 weeks) with removal depending on radiographic evidence of fracture union.

Summary: The COBRA external fixator is a versatile tool in the treatment of intra-articular and extra-articular fractures that any general orthopaedic surgeon can use. The overall functional and anatomical outcome is good to excellent during the time of fixation up to the time of fixator removal. Hand and wrist function is initiated immediately markedly limiting the usual complications of stiffness and disability commonly associated with these fractures.

Aim: The objective of this study was to compare the initial stability of an uncemented curved long stem femoral component (ABR, Zimmer, Warsaw Indiana) implanted using conventional broaching to an uncemented ABR implanted as a revision using morselized compacted allograft to fill a circumferential proximal bone defect.

Materials and Methods: Primary: Eight fresh frozen human femurs were implanted with correctly sized ABR stems without cement using standard surgical instruments and 1mm distal overreaming. The implant was loaded cyclically at 3 hz on a MTS servohdraulic materials test frame in a direction representing the peak force of the stance phase of the gait (2.5 X body weight). A 3-dimensional motion measurement device with six linear variable transformers measure the relative motion between the bone and the prosthesis with an accuracy of 0.5μm. The contruct was loaded in ten cycle increments until the component was seated and then recoverable motion was recorded over a further ten loading cycles. Revision: In the revision case bone loss was modelled by removing all the cancellous bone from the proximal femur with 1mm distal overreaming. Morselized bone graft was impacted into the defect using specially prepared smooth tamps shaped to the geometry of the ABR stem. The original prosthesis was then reimplanted without the use of cement. The seating and testing cycles were repeated. Primary and revision vectors were compared using a paired students t – test.

Results: There was no statistically significant difference in the magnitude of the resultant vector of the 3 translational components of the micro motion between the two methods of implantation (p=0.19).

Conclusions: Initial stability of a cementless femoral implant is a requirement for bone ingrowth. The use of compacted morsellized allograft in a revision Total Hip Arthroplasty with a proximal circumferential defect can provide a stable bed for the implantation of an uncemented femoral component. The revised implant using the compacted allograft method was initially as stable as the primary implantation.

This technique would be particularly applicable when the surgeon would like to avoid the use of cement in a revision setting. The use of this method for uncemented revision Total Hip Arthroplasty should be studied further in a clinical setting before it is advocated for widespread use.