Department of Surgical Sciences

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Browsing Department of Surgical Sciences by browse.metadata.advisor "Ferreira, Nando"

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    Continuous irrigation as dead space management for fracture related type 1 intramedullary chronic osteomyelitis
    (Stellenbosch : Stellenbosch University, 2022) Grey, Jan-Petrus; Ferreira, Nando; Burger, Marilize Cornelle; Faculty of Medicine and Health Sciences. Dept. of Surgical Sciences. Orthopaedic Surgery.
    ENGLISH ABSTRACT: Introduction: Dead space management following intramedullary debridement and reaming can be challenging and several alternatives have been described. The main objective of this study was to investigate the clinical outcome and resolution rate in patients treated for fracture related Cierny and Mader anatomical type 1 intramedullary chronic osteomyelitis by means of continuous irrigation (modified Lautenbach system) as dead space management following intramedullary reaming. Material and Method: A consecutive series of thirty patients with Cierny and Mader type 1 chronic osteomyelitis, treated between May 2016 and September 2019, were evaluated retrospectively. Patient history and clinical information, including imaging and laboratory results, were reviewed. Treatment procedures and antibiotic profiles were also recorded. Results: The initial cohort included 30 cases with 18 tibias, 11 femurs and one humerus. Seven patients were excluded; three patients did not return for follow up and four patients had less than six months follow up. Of the remaining 23 patients, 91% (21/23) achieved resolution of infection over a median follow up period of 16 months (Interquartile range, IQR 7-21 months). Infecting organisms where isolated in 65% (15/23). The median duration of hospital stay was 6 days (IQR 4-7 days). Post-operative complications were noted in two cases and involved a tibial and femoral refracture, respectively. Both patients however achieved union without recurrence of infection following surgical intervention. Conclusion: Continuous irrigation is a cost-effective single-stage surgical option for dead space management during the treatment of intramedullary chronic osteomyelitis. It provides the advantage of instilling high dose intramedullary antibiotics and negates the need for a second surgical procedure while achieving similar outcomes than other dead space management techniques.
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    The modification and testing of an anatomically shaped radius and ulna interlocking intramedullary nail using statistical shape modelling derived from computed tomography scans.
    (Stellenbosch : Stellenbosch University, 2023-03) Pretorius, Henry Sean; Ferreira, Nando; Burger, Marilize; Faculty of Medicine and Health Sciences. Dept. of Surgical Sciences. Orthopaedic Surgery.
    ENGLISH ABSTRACT: The management of either segmental or comminuted complicated radius and ulna fractures and metastatic disease remains challenging for orthopaedic surgeons. Compression or bridge plate fixation has been insufficient to manage some of these injuries. The advent of locked intramedullary nailing provided a novel way to traverse the entire length of the affected bone and provided an effective treatment option for both simple and comminuted fractures. However, one of the challenges with these devices was the freehand locking of the nondriving end of these nails, which made these systems less popular even though the healing times and union rates were comparable to the plating. The specific issues with locking nails of the forearm relates to the non-driving end locking, where the size of the locking hole is small and can be a challenge to lock, as well as the location of the nail, specifically regarding the proximal radius with the radial nerve in the surgical field. The next issue is the increments of nail length and girth, with nail sizes of 4mm and 6mm diameter and the length increments of 20mm, making the correct nail size choice difficult. The natural curve of the radius needs to be corrected to restore anatomy, but since this is usually a guess related to the opposite side, no approximation has been standardised. The primary basis of design for the intramedullary nail is to establish the correct anatomy of the relevant forearm bones in order to have a reliable measurement to extrapolate the required length, diameter and curvature of the nail. The initial anatomical study allowed us to establish the minimum nail length required by using the shortest radius length as the minimum nail length of 225mm as the shorter bone and the ulna length as the maximum nail length of 265mm as it is the longer bone. The prosthesis was designed with 10mm length increments. The same principle was used to decide on the optimal nail diameter of 4.5mm, with the minimum diameter being 4.87 and 4.53 for the radius and ulna, respectively. Each of the forearm bones has a unique curve with the radius having an arc with a measurable radius of curvature in the medullary canal of 561.93mm ± 93.49 (543.09–580.78). The ulna has a varus angulation of 11.39o ± 3.13 (10.76–12.02). These are measurements that the surgeon can use to bend the prosthesis to the appropriate curve or use the average if this cannot be calculated. The previously mentioned problem with freehand locking of the nail has been that it is technically difficult to perform, and the excessive fluoroscopic radiation exposure required to achieve interlocking. To mitigate this problem in the design, a screw hole was created using arrow slit technology from medieval castles that allow excellent viewing and shooting angles through a small hole. This creates a locking hole with a large aperture on the surface and a 35o approach angle which enables the drill to skirt the edge of the funnel-shaped edge and traverse the hole with minimal problems as the funnel shape is reciprocated on the opposite side. The results from the anatomical study were critical in establishing specific design characteristics of the nail. These results were further used in a linear regression model to predict characteristics for surgical planning or anthropological measurements. A mathematical formula was created from the regression to predict radial length using the ulna length with an 85% (R2 = 0.85) accuracy. The minimum diameter of the radius and ulna canals and the ulna length can be predicted using various measurements inserted into a unique mathematical formula for each. The formula predicts the parameter with an R2 of more than 0.80. These measurements can be used to choose an appropriate nail size for the respective bones. The nail design progressed through computer-aided 3D drawings and 3D printed plastic prototypes with the anatomical measurement data as a guide. Jigs and drill sleeves were designed using the same system, with minor adjustments being made, and the eventual product was created. Medical implant-grade titanium was used for the prototypes, and rough design jigs were also manufactured for testing. A cadaver study was undertaken, emphasising nail fit into the radius and ulna and the ability to achieve interlocking at the non-driving end. This was done by recording the time for the locking screw hole to be drilled and x-ray exposures needed to accomplish this. The locking time is within reason, usually a relatively consistent variable, as the procedure and fracture reduction are typically unique to each trauma. The longest locking time was 112 seconds, and the maximum number of exposures was 12. This compared well to the available literature on the topic. Several minor issues arose during the testing phase with mechanical breaking or wearing of parts on the nail or jig systems. The problems were reported to the engineering teams, and replacements were redesigned and manufactured, which were also tested during the cadaver study phase. The final nail design underwent mechanical testing to evaluate the fatigability of the implant. The process was done to international standards (ASTM F1264-16) and showed that the nail would withstand significant mechanical forces before breaking. The maximum force needed for radius and ulna fixation is 250N, the nail was found to withstand 440N of stress 90% of the time with 1 million cycles applied. The number of cycles relates to the time it will take for the fracture to heal, as it usually requires about three months to accumulate a million cycles with regular activity. This means the nail will withstand most normal physiological forces through movement or exercise. With all the anatomical research, product design, and testing that has been done for this project, the forearm nail that has been produced has passed all the tests and is now ready for clinical testing in trauma patients. The process has now been started to ethically engage in testing this project, which shows the thesis aims have been achieved.
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    The Radiological Assessment to determine whether the use of assistive devices improve Syndesmotic screw placement during surgical fixation of ankle fractures
    (Stellenbosch : Stellenbosch University, 2022-07) Kriel, Renier; Ferreira, Nando; Burger, Marilize Cornelle; Faculty of Medicine and Health Sciences. Dept. of Surgical Sciences. Orthopaedic Surgery.
    ENGLISH ABSTRACT: Background: Ankle fractures are common injuries, and syndesmotic instability can pose a challenge to the inexperienced surgeon. This study aimed to investigate whether the aid of an assistive device as part of the standard of practice, namely the adapted technique, improves the accuracy of syndesmotic screw placement and reduction of the syndesmosis, compared to the traditional free-hand technique during the operative management of ankle fractures. Methods: This post-operative radiological assessment serves as a retrospective comparative series. Standard anterior-posterior radiographs were used to measure the height of the screw from the ankle joint line, and axial computed tomography slices at the level of the syndesmosis screw were used to measure the trajectory of screw placement against that of the ideal syndesmotic line, as well as the anterior and posterior syndesmotic spaces. Results: A total of 67 post-operative ankles were included (n=56 in the free-hand group vs n=11 in the adapted technique group). A difference between the height of screw placement was observed when comparing the historical free-hand technique to the adapted technique (p=0.002). No significant difference for the angle deviation or anterior- and posterior syndesmotic spaces was observed between the two groups. A trend (p=0.074) was observed with the free-hand technique associated with a larger deviation from the intended screw trajectory. Conclusion: Simple assistive devices may improve the accuracy of syndesmotic screw placement in terms of height and trajectory during the operative management of ankle fractures.
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    Radiolographic assessment of lower limb alignment in South African children
    (Stellenbosch : Stellenbosch University, 2022-07) Foxcroft, William Donnavan; Du Toit, Jacques; Burger, Marilize Cornelle; Ferreira, Nando; Faculty of Medicine and Health Sciences. Dept. of Surgical Sciences. Orthopaedic Surgery.
    ENGLISH ABSTRACT: Background: Radiographic measurements on full length standing lower limb views are the standard for lower limb deformity analysis. Published measurements of Paley et al. on lower limb alignment is the gold standard but was derived from small adult samples. There are no radiographic measurements reported exclusively of children of South African descent. The study aimed to establish normal values of lower limb alignment and joint orientation angles in South African children between 5 and 18 years old, at specific age intervals and to compare these measurements to the values as derived from Paley et al. Methods: A cross-sectional radiographic study including all 5-18 year old children who underwent full-length anteroposterior radiographs between 2012 and 2020 was conducted. Radiographic measurements were done as described by Paley. Differences in measurements obtained and those reported by Paley et al.1 were investigated using a T-test for a single mean against a reference constant, using an alpha level of 0.05. Results: A total of 190 patients (110 male; 80 female) with a mean age of 10.0 ± 3.3 years were included. The medial neck-shaft angle (MNSA), mechanical and anatomical lateral distal femoral angle (LDFA) and lateral distal tibia angle (LDTA) remained consistent throughout the age groups. Significant differences between Paley’s published values and our cohort were observed for the median mechanical axis deviation (MAD), MNSA and medial proximal tibia angle (MPTA). The median MAD across age groups was -2.2 mm (IQR -6.4 – 1.5) with all subgroups showing a lateral MAD (valgus alignment), compared to the median MAD of +9.7mm (varus alignment) from Paley et al.1 The MNSA had a mean of 135.7°, compared to 129.7° from Paley. The mean MPTA was 89.7°, compared to Paley’s 87.2°. The MPTA had minimal change throughout the age groups. Conclusion: Significant differences were seen in the mean/median of our MAD, MNSA and MPTA compared to Paley’s work. Our MAD have a sustained valgus tibio-femoral angulation throughout our population. Our MNSA have more pronounced valgus with minimal change throughout growth. The increasing MPTA leads to a more valgus joint line when compared to other studies. Other measured values are comparable with previously published adult and paediatric populations. We were able to develop set values that could be the norm for paediatric joint orientation angles in the South African population.