Effects of processing and gamma radiation on mechanical properties and organic composition of frozen, freeze-dried and demineralised human cortical bone allograft.

Bone processing and radiation were reported to influence mechanical properties of cortical bones due in part to structural changes and denaturation of collagen composition. This comparative study was to determine effects of bone processing on mechanical properties and organic composition, and to what extent the radiation damaging after each processing. Human femur cortical bones were processed by freezing, freeze-drying and demineralisation and then gamma irradiated at 5, 15, 20, 25 and 50 kGy. In the compression test, freeze drying significantly decreased the Young's Modulus by 15%, while demineralisation reduced further by 90% (P < 0.05) when compared to the freezing. Only demineralisation significantly reduced ultimate strength of bone by 93% (P < 0.05). In the bending test, both freeze drying and demineralisation significantly reduced the ultimate strength and the work to failure. Radiation at 25 kGy showed no effect on compression for ultimate strength in each processing group. However, high dose of 50 kGy significantly reduced bending ultimate strength by 47% in demineralisation group. Alterations in collagen in bones irradiated at 25 and 50 kGy showed by the highest peak of the amide I collagen in the Fourier Transfer Infra-Red spectra indicating more collagen was exposed after calcium was removed in the demineralised bone, however radiation showed no effect on the collagen crosslink. The study confirmed that demineralisation further reduced the ability to resist deformation in response to an applied force in freeze-dried bones due to calcium reduction and collagen composition. Sterilisation dose of 25 kGy has no effect on mechanical properties and collagen composition of the processed human cortical bone.

Evaluating the risk of popliteal artery injury in the all-inside meniscus repair based on the location of posterior meniscal lesions.

The 'all-inside' meniscus repair is extremely useful technique in addressing tears at the far posterior horn of meniscus. However, this procedure may place the popliteal neurovascular bundle at risk of injury. The purpose of this study was to evaluate the risk of popliteal artery injury by the trajectory of anchor delivery instruments inserted through standard knee arthroscopic portals for the repair of the far posterior horn of meniscus tears. Standard arthroscopic portals were marked on five human cadaveric knees which were subsequently disarticulated. Axial photographs were taken after marking the 5 10, and 15 mm points from the meniscal root on the posterior horns of the menisci. The unsafe zones for meniscus repair at each of these points were identified on the photographs of knees by first drawing two lines from the edges of the popliteal artery and crossing at the respective points at the posterior horns. The points at which these lines meet a circular protractor applied to the center of each meniscus in the knee photograph were recorded as a range. The range signifies the unsafe zone for each respective point on the posterior horn of meniscus. The anterolateral arthroscopic portal fell within the unsafe zone of the 5 mm point on the posterior horn of lateral meniscus in three of the five knees and within the unsafe zone of the 10 mm point on the posterior horn of lateral meniscus in another two knees. A cautious approach should be practiced during the repair of tears located at these two points. None of the other points' unsafe zones (lateral 15 mm, medial 5 mm, 10 mm and 15 mm points) coincided with the ipsilateral portal sites. Level of evidence 5 (Human cadaveric study).

Performance of cooling materials and their composites in maintaining freezing temperature during irradiation and transportation of bone allografts.

PURPOSE: Bone allografts supplied by University Malaya Medical Centre Bone Bank are sterilized by gamma radiation at 25 kGy in dry ice (DI) to minimize radiation effects. Use of cheaper and easily available cooling materials, gel ice (GI) and ice pack (IP), was explored. Composites of DI and GI were also studied for the use in routine transportations and radiation process. METHODS: (a) Five dummy bones were packed with DI, GI, or IP in a polystyrene box. The bone temperatures were monitored while the boxes were placed at room temperature over 96 h. Durations for each cooling material maintaining freezing temperatures below -40°C, -20°C, and 0°C were obtained from the bone temperature over time profiles. (b) Composites of DI (20, 15, 10, 5, and 0 kg) and GI were used to pack five dummy bones in a polystyrene box. The durations maintaining varying levels of freezing temperature were compared. RESULTS: DI (20 kg) maintained temperature below -40°C for 76.4 h as compared to 6.3 h in GI (20 bags) and 4.0 h in IP (15 packs). Composites of 15DI (15 kg DI and 9 GI bags) and 10DI (10 kg DI and 17 GI bags) maintained the temperature below -40°C for 61 and 35.5 h, respectively. CONCLUSION: Composites of DI and GI can be used to maintain bones in deep frozen state during irradiation, thus avoiding radiation effects on biomechanical properties. Sterile frozen bone allograft with preserved functional properties is required in clinical applications.

Correlation between anatomy of the scapula and the incidence of rotator cuff tear and glenohumeral osteoarthritis via radiological study.

INTRODUCTION: We conducted a study to elucidate the correlation between the anatomy of the shoulder joint with the development of rotator cuff tear (RCT) and glenohumeral osteoarthritis (GHOA) by using acromioglenoid angle (AGA). MATERIALS AND METHODS: The AGA is a new measured angle formed between the line from midglenoid to lateral end of the acromion with the line parallel to the glenoid surface. The AGA was measured in a group of 85 shoulders with RCT, 49 with GHOA and 103 non-RCT/GHOA control shoulders. The AGA was compared with other radiological parameters, such as, the critical shoulder angle (CSA), the acromion index (AI) and the acromiohumeral interval (AHI). Correlational and regression analysis were performed using SPSS 20. RESULTS: The mean AGA was 50.9° (45.2-56.5°) in the control group, 53.3° (47.6-59.1°) in RCT group and 45.5° (37.7-53.2°) in OA group. Among patients with AGA > 51.5°, 61% were in the RCT group and among patients with AGA < 44.5°, 56% were in OA group. Pearson correlation analysis had shown significant correlation between AGA and CSA ( r = 0.925, p < 0.001). It was also significant of AHI in RCT group with mean 6.6 mm (4.7-8.5 mm) and significant AI in OA group with mean 0.68 (0.57-0.78) with p value < 0.001 respectively. CONCLUSION: The AGA method of measurement is an excellent predictive parameter for diagnosing RCT and GHOA.

Assessing bone banking activities at University of Malaya medical centre.

The main advantage of establishing in-house bone banks is its ability to readily provide allograft bones for local surgeries. Bone procurement activities of our university bone bank during the 10 years of operation were reviewed. Socio-demographic data of donors, types of bone procured, cases of rejected bones and types of allograft bones transplanted are presented. From 179 potential donors, 73 % were accepted with 213 procured bones. Femoral head was the common bone transplanted (45 %), as it was also the most common procured (82 %). Bones were rejected mainly due to non-technical reasons (83 %) rather than positive results of microbiological (13 %) and serological (4 %) tests. Comprehensive data could not be obtained for further analysis due to difficulties in retrieving information. Therefore, quality assurance system was improved to establish more systematic documentations, as the basis of good banking practice with process control hence allowing traceability.