Objectives

To conduct a pilot randomised controlled trial to evaluate the feasibility of conducting a larger trial to evaluate the difference in Victorian Institute of Sports Assessment-Achilles (VISA-A) scores at six months between patients with Achilles tendinopathy treated with a platelet-rich plasma (PRP) injection compared with an eccentric loading programme.

During revision total knee arthroplasty (rTKA), proximal tibial bone loss is frequently encountered and can result in a less-stable bone-implant fixation. A 3D printed titanium alloy (Ti6Al4V) revision augment that conforms to the irregular shape of the proximal tibia was recently developed. The purpose of this study was to evaluate the fixation stability of rTKA with this augment in comparison to conventional cemented rTKA. Eleven pairs of thawed fresh-frozen cadaveric tibias (22 tibias) were potted in custom fixtures. Primary total knee arthroplasty (pTKA) surgery was performed on all tibias. Fixation stability testing was conducted using a three-stage eccentric loading protocol. Static eccentric (70% medial/ 30% lateral) loading of 2100 N was applied to the implants before and after subjecting them to 5×103 loading cycles of 700 N at 2 Hz using a joint motion simulator. Bone-implant micromotion was measured using a high-resolution optical system. The pTKA were removed. The proximal tibial bone defect was measured. One tibia from each pair was randomly allocated to the experimental group, and rTKA was performed with a titanium augment printed using selective laser melting. The contralateral side was assigned to the control group (revision with fully cemented stems). The three-stage eccentric loading protocol was used to test the revision TKAs. Independent t-tests were used to compare the micromotion between the two groups. After revision TKA, the mean micromotion was 23.1μm ± 26.2μm in the control group and 12.9μm ± 22.2μm in the experimental group. There was significantly less micromotion in the experimental group (p= 0.04). Prior to revision surgery, the control and experimental group had no significant difference in primary TKA micromotion (p= 0.19) and tibial bone loss (p= 0.37). This study suggests that early fixation stability of revision TKA with the novel 3D printed titanium augment is significantly better then the conventional fully cemented rTKA. The early press-fit fixation of the augment is likely sufficient for promoting bony ingrowth of the augment in vivo. Further studies are needed to investigate the long-term in-vivo fixation of the novel 3D printed augment

Introduction. Tendinopathies are debilitating and painful conditions. They are believed to result from repetitive overuse, which can create micro-damage that accumulates over time, and initiates a catabolic cell response. The aetiology of tendinopathy remains poorly understood, therefore the ideal treatment remains unclear. However, current data support the use of eccentric exercise as an effective treatment. In a previous study, we have shown that eccentric loading generates perturbations in the tendon at 10Hz, which is not present during other less effective loading regimes. Consequently, we hypothesis that 10Hz loading initiates an increased anabolic response in tenocytes, that can promote tendon repair. Materials and Methods. Human tenocytes from healthy hamstring tendons and tendinopathic Achilles tendons were derived by collagenase digest and outgrowth respectively. Tenocytes were seeded into 3D collagen gels. The gels were fixed in custom-made chambers and placed in an incubator for 24hrs whilst gene expression stabilised. After 24hrs, cyclic uniaxial strain at 1% ± 1% was applied to the cells, at either 1Hz (n=4) or 10Hz (n=4) using a Bose loading system. After 15 minutes of cyclic strain, the samples were maintained in chambers under 1% static strain for 24 hrs after which gene expression was characterised using RT-PCR. Results. In healthy cells, data showed an increase in expression of all analysed genes after loading (MMP1, MMP2, MMP13, COL1A1, COL3A1, COL5A1, ADAMTS5, IL6, IL8 and TIMP3). Furthermore, the increase in gene expression was larger in the higher frequency loading group, across all genes. Tendinopathic cells showed a more varied response, with upregulation of MMP1, MMP13, COL3A1, ADAMTS5, IL6 and IL8, and downregulation of COL1A1 and COL5A1. Once again, all changes were more pronounced in the higher frequency loading group. Discussion. These preliminary data suggest increased matrix turnover as a result of loading, particularly with high frequency loading in healthy tenocytes, whilst the profile of tendinopathic cells, may indicate an early healing response, where collagen type III is preferentially unregulated relative to types I and V. High frequency loading elicited a more pronounced cellular response, perhaps correlating with the improved repair seen with eccentric loading in vivo

Introduction: Treatment options for the young active patient with isolated symptomatic medial compartment OA and pre-existing ACL deficiency are limited. Implant longevity and activity levels may preclude TKA, whilst HTO and unicompartmentasl knee arythroplasty (UKA) are unreliable due to ligamentous instability. UKAs tend to fail because of wear or tibial loosening resulting from eccentric loading. Combined UKA and ACL reconstruction may therefore be a solution. Method: Fifteen patients with combined ACL reconstruction and Oxford UKA (ACLR group), were matched (age, gender and follow-up period) with 15 patients with Oxford UKA with intact ACL (ACLI group). Prospectively collected clinical and x-ray data from the last follow-up (minimum 3 years, range: 3 – 5) were compared. Ten patients from each group also underwent in-vivo kinematic assessment using a standardised protocol. Results: At the last follow-up, the clinical outcome for the two groups were similar. One ACLR patient needed revision due to infection. Radiological assessment did not show any significant difference between relative component positions and none of the patients had pathological radiolucencies suggestive of component loosening. Kinematic assessment showed posterior placement of the femur on tibia in extension for the ACLR group, which corrected with further flexion. Conclusions: The short-term clinical results of combined ACL reconstruction and UKA are excellent. Lack of pathological radiolucencies and near normal knee kinematics suggest that early tibial loosening due to eccentric loading is unlikely

Introduction: Treatment options for the young active patient with isolated symptomatic medial compartment osteoarthritis and pre-existing anterior cruciate ligament (ACL) deficiency are limited. Implant longevity and activity levels may preclude total knee arthroplasty (TKA), whilst high tibial osteotomy HTO and unicompartmental arthroplasty (UKA) are unreliable due to ligamentous instability. UKA’s tend to fail because of wear or tibial loosening resulting from eccentric loading. Combined UKA and ACL reconstruction may therefore be a solution. Method: Fifteen patients with combined ACL reconstruction and Oxford UKA (ACLR group), were matched (age, gender and follow-up period) with 15 patients with Oxford UKA with intact ACL (ACLI group). Prospectively collected clinical and x-ray data from the last follow-up (minimum 3 years, range: 3–5) were compared. Ten patients from each group also underwent in-vivo kinematic assessment using a standardised protocol. Results: At the last follow-up, the clinical outcome for the two groups were similar (ACLR: OKS 46, KSS (objective): 99, ACLI: OKS 43, KSS (objective): 94). One ACLR patient needed revision due to infection. Radiological assessment did not show any significant difference between relative component positions and none of the patients had pathological radiolucencies suggestive of component loosening. Kinematic assessment showed posterior placement of the femur on tibia in extension for the ACLR group, which corrected with further flexion. Conclusions: The short-term clinical results of combined ACL reconstruction and UKA are excellent. Lack of pathological radiolucencies and near normal knee kinematics suggest that early tibial loosening due to eccentric loading is unlikely. Similarly, wear is unlikely to be a problem because of the wear resistance of mobile bearing devices

Aim. The aim of this FE study was to analyse the comparative behaviour of cement and metal based augments in TKR and quantify the stresses within these different augments and underlying cancellous bone. Materials and methods. A three-dimensional FE model was constructed from a CT scan of the proximal tibia using SIMPLEWARE v3.2 image processing software. The tibial component of a TKR was implanted with either a block or wedge-shaped augment made of either metal or cement. The model was axially loaded with a force of 3600N and testing was conducted with both evenly and eccentrically distributed loads. Results. Upon loading the FE model, the von-Mises stresses in the cancellous bone underneath the augments was higher with cement based augments in comparison their metal counterparts. When evenly loaded the maximum recorded compressive stresses within the metal augments were 5 times less than the endurance limit of the material, whilst the stresses within cement augments were only half the endurance limit of the material. Upon eccentric loading compressive stresses within the cement based augments in excess of the endurance limit were recorded. Discussion. The FE model has demonstrated that cement based augments undergo greater deformation when loaded and transfer greater loads to the underlying cancellous bone thus reducing the possibility of stress shielding. However, the compressive stresses within cement based augments are too close to the endurance limit of the material and with uneven loading even exceed it. This would imply that cement based augments are more prone to fatigue failure than their metal counterparts. Conclusion. This study supports the use of metal over cement based augments in augmented and revision TKR surgery

Background. While total shoulder arthroplasty (TSA) is a generally successful procedure, glenoid loosening remains a common complication. Though the occurrence of loosening was related to patient-specific factors, biomechanical factors related to implant features may also affect the fixation of the glenoid component, in particular increased glenohumeral mismatch that could result in eccentric loads and translations. In this study, a novel test setup was used to quantify glenohumeral pressures for different motion patterns after TSA. Methods. Six cadaveric human shoulders were implanted with total shoulder replacements (Exactech, Inc., USA) and subjected to cyclic internal-external, flexion-extension and abduction-adduction rotations in a passive motion testing apparatus. The system was coupled to a pressure sensor system (Tekscan, Inc., USA) to acquire joint loads and to a Zebris system (Zebris Medical, GmbH, Germany) to measure joint kinematics. The specimens were subjected to a total of 2160 cycles and peak pressures were compared for each motion pattern. Results. It was shown that during abduction the contact area between the humeral head and the glenoid component shifts from a posterior to an anterior position, while also moving inferiorly. For internal-external rotation a mean peak pressure of 8.37 ± 0.22 MPa was registered, while for flexion-extension a pressure of 9.37 ± 0.38 MPa and for abduction-adduction a pressure of 9.88 ± 0.07 MPa were obtained. Conclusion. This study showed how glenohumeral pressures after TSA vary during simulated internal-external, flexion-extension and abduction-adduction rotations in a cyclic testing setup. It showed that peak loads are mainly obtained in abduction, and that these occurred mainly near the anterior part of the glenoid. Future steps involve implantation of other type of anatomical glenoid components to obtain different levels of glenohumeral mismatch and relating the 3D measurements of motion patterns to contact pressures

Introduction. In complex primary and revision total knee replacement (TKR) the operating surgeon may encounter proximal tibial bone defects. The correct management of such defects is fundamental to both the initial stability and long-term survival of the prosthesis. Cement or metal augments have been used to address some such type II unconstrained defects [1]. Aim. The aim of this finite element (FE) study was to analyse the comparative behaviour of cement and metal based augments and quantify the stresses within these different augments and underlying cancellous bone. Materials and methods. A three-dimensional FE model was constructed from a computer tomography (CT) scan of the proximal tibia using SIMPLEWARE v3.2 image processing software. The tibial component of a TKR was implanted with either a block or wedge-shaped augment made of either metal or cement. The model was axially loaded with a force of 3600N and testing was conducted with both evenly and eccentrically distributed loads. Results. Upon loading the FE model, the von-Mises stresses in the cancellous bone underneath the augments were found to be higher with cement based augments in comparison their metal based counterparts. This was evident with both block and wedge-shaped augments. The FE model demonstrated that compressive stresses within the metal based augments were greater than those within the cement based augments. This was evident with both block and wedge designs. Upon even loading the maximum recorded compressive stresses within the metal augments were 5 times less than the endurance limit of the material [3]. However, the maximum recorded compressive stresses within cement augments were only half the endurance limit of the material [4] and upon eccentric loading compressive stresses in excess of the endurance limit were recorded. Discussion. The FE model has demonstrated that cement based augments undergo a greater deformation when loaded and therefore transfer greater loads to the underlying cancellous bone. This is a result of the inherent flexibility of the cement based augment in comparison to the stiffer metal counterparts. The greater transference of load to cancellous bone with cement based augments may reduce the possibility of stress shielding. However, the compressive stresses within cement based augments are too close to the endurance limit of the material and with uneven loading even exceed it. This would imply that cement based augments are more prone to fatigue failure than their metal counterparts. Conclusion. This FE study supports the use of metal based augments over cement based augments in augmented and revision TKR surgery

Background. Distal femoral replacements (DFR) are used in children for limb-salvage procedures after bone tumor surgery. These are typically modular devices involving a hinged knee axle that has peripheral metal-on-polyethylene (MoP) and central metal-on-metal (M-M) articulations. While modular connections and M-M surfaces in hip devices have been extensively studied, little is known about long-term wear or corrosion mechanisms of DFRs. Retrieved axles were examined to identify common features and patterns of surface damage, wear and corrosion. Methods. The cobalt chromium alloy axle components from 13 retrieved DFRs were cleaned and examined by eye and with a stereo microscope up to 1000× magnification. Each axle was marked into 6 zones for visual inspection: the proximal and distal views, and the middle (M-M) and 2 peripheral (MoP) zones. The approximate percentage of the following features were recorded per zone: polishing, abrasion or scratching, gouges or detectable wear, impingement wear (i.e. from non- intentional articulation), discoloration and pitting. Results. In each case, the middle M-M zones showed more damage features compared with peripheral MoP zones. Brown discoloration, presumably due to tribofilm deposits, was the predominant M-M area feature, particularly at the junction between the MoP and M-M zones. Higher magnification showed areas of polishing underlying the discoloration, suggesting repetitive removal of the surface metal and re-deposition of tribofilms (Fig 2B). 9 cases demonstrated reflective patches resembling “thumbprint” or “fish scale” markings, which, under higher magnification, showed signs of scratching and grooving in a radial pattern (Figs 2D, 3A). Pits were occasionally present but appeared to be from third-body damage as signs of corrosion were absent. Features that resembled carbides, sometimes with associated “comet” patterns of scratching were apparent under higher magnification in some areas. The MoP zones showed variable scratching, abrasion and wear polishing. The MoP to M-M junctional areas were demarcated by a distinct band corresponding, in some cases, to a narrow wear groove or gouge. 3 axles showed evidence of severe impingement wear on one proximal end. Discussion. This study of retrieved axle components demonstrated varying types of surface wear damage but no clear evidence of corrosion. This is presumably because these parts are in nearly constant motion during gait. Third-body damage may have resulted from the breakdown of surface carbides, leading to scratching, abrasion and wear polishing under high contact stress. Severe impingement wear presumably occurred after catastrophic damage to the polyethylene bushings, allowing eccentric loading and extensive metal wear. The components were revised for a range of clinical reasons including aseptic loosening and the need to expand the prosthesis during growth. With the exception of the few cases with severe impingement, it is unlikely that the wear features seen here contributed to the need for revision. While it was reassuring that corrosion was not a prominent feature of these modular M-M articulations, retrieval analysis of DFR components should be continued to confirm this finding, better document the in vivo wear processes and point to design features that might be improved for future patients. For any figures or tables, please contact the authors directly

The options for treatment of the young active patient with isolated symptomatic osteoarthritis of the medial compartment and pre-existing deficiency of the anterior cruciate ligament are limited. The potential longevity of the implant and levels of activity of the patient may preclude total knee replacement, and tibial osteotomy and unicompartmental knee arthroplasty are unreliable because of the ligamentous instability. Unicompartmental knee arthroplasties tend to fail because of wear or tibial loosening resulting from eccentric loading. Therefore, we combined reconstruction of the anterior cruciate ligament with unicompartmental arthroplasty of the knee in 15 patients (ACLR group), and matched them with 15 patients who had undergone Oxford unicompartmental knee arthroplasty with an intact anterior cruciate ligament (ACLI group). The clinical and radiological data at a minimum of 2.5 years were compared for both groups. The groups were well matched for age, gender and length of follow-up and had no significant differences in their pre-operative scores. At the last follow-up, the mean outcome scores for both the ACLR and ACLI groups were high (Oxford knee scores of 46 (37 to 48) and 43 (38 to 46), respectively, objective Knee Society scores of 99 (95 to 100) and 94 (82 to 100), and functional Knee Society scores of 96 and 96 (both 85 to 100). One patient in the ACLR group needed revision to a total knee replacement because of infection. No patient in either group had radiological evidence of component loosening. The radiological study showed no difference in the pattern of tibial loading between the groups. The short-term clinical results of combined anterior cruciate ligament reconstruction and unicompartmental knee arthroplasty are excellent. The previous shortcomings of unicompartmental knee arthroplasty in the presence of deficiency of the anterior cruciate ligament appear to have been addressed with the combined procedure. This operation seems to be a viable treatment option for young active patients with symptomatic arthritis of the medial compartment, in whom the anterior cruciate ligament has been ruptured

Humeral head size is defined by the radius of curvature and the thickness of the articular segment. This ratio of radius to thickness is within a narrow range with an average of 0.71. The articular surface of the normal humeral head measured within the AP plane is defined by three landmarks on the non-articular surface of the proximal humerus. The perfect circle concept can be applied for assessment of the anatomic reconstruction of the post-operative x-rays and more importantly can be used intra-operatively as a guide when choosing the proper prosthetic humeral head component. The humeral head is an elliptical shape with its AP dimension being approximately 2 mm less than the SI dimension. This shape contributes to the roll and translation of the normal shoulder but is not replicated by the spherical shape of the prosthetic humeral head. The glenoid vault has a consistent 3D shape and use of the vault model within 3D planning software can define the patient's pre-morbid anatomy, specifically the location of the joint line and patient specific version and inclination. Use of this tool can assist the surgeon in defining the optimal implant and its location. In patients with little or no bone loss, a symmetric glenoid implant is often ideal for resurfacing. When there is asymmetric bone loss, often seen posteriorly with osteoarthritis, an asymmetric posteriorly augmented component can improve the ability to correct the deformity while maintaining the native joint line. It is suggested that these augmented implants in selected patients will help restore and maintain humeral alignment and lessen the risk for residual posterior humeral head subluxation and eccentric loading of the glenoid component

While the vast majority of total knee replacements performed throughout the world employ a modular metal-backed tibial tray, and not an all-polyethylene tray, this issue remains controversial. Proposed advantages to a metal-backed tray include: a) decreased bending strains, b) reduces compressive stresses in the cement and cancellous bone beneath the baseplate (especially in asymmetric loading), c) distributes load more evenly across the interface. Proposed advantages of an all-polyethylene tray include: a) cost reduction, b) reduced polyethylene thickness with the same amount of bone resection, c) increased tensile stresses at the interface during eccentric loading. The challenge is at present we don't know the >10-year track record of current generation tibial components. This debate centers on the <60-year-old. This is the most difficult patient in total knee arthroplasty with higher revision rates than an older cohort. It makes sense to use an all-polyethylene tibia if the revision rates turn out to be similar and you don't intend to do a polyethylene exchange in the future. It makes sense to do a modular tray if the results are similar, but there is an intention to do a polyethylene exchange in the future. If either one of these implants choices has a lower cumulative revision rate, then that is the implant of choice at present. However, we need to understand that at present we don't know if the results of current generation all-polyethylene tibial components will indeed be equal to metal-backed components. The most recent data from the Australian registry suggests that in fact all-polyethylene tibial components have a higher failure rate than metal-backed components when looking at the entire class of design. This would be expected to be even more significant in the younger patient

Introduction. Clinical observations suggest mid-flexion instability may occur more commonly with rotating platform (RP) total knee arthroplasty (TKA), including increased revision rates and patient-reported instability and pain. We propose that increased gap laxity leads to liftoff of the lateral femoral condyle with decreased conformity between the femoral component and polyethylene (PE) insert surface leading to PE subluxation or dislocation. The objectives of this study were to define “at risk” loading conditions that predispose patients to PE insert subluxation or spinout, and to quantify the margin of error for flexion/extension gap laxity in preventing these adverse events under physiologic loading conditions. Methods. Biomechanical testing was performed on six fresh frozen cadaveric knees implanted with a posterior stabilized RP TKA using a gap balancing technique. Rotational displacement and torque were measured over time, while stiffness, yield torque, max torque and displacement were calculated using a post-processing, custom MatLab code. Revision with varying size femoral components (size 3–6) and PE insert thicknesses (10–15mm), by downsizing one step, were used to create a spectrum of flexion/extension gap mismatch. Each configuration was subjected to three loaded testing conditions (0°, 30° and 60° flexion) in balanced and eccentric varus loading, known to represent daily clinical function and “at risk” circumstances. Results. PE insert rotational instability was primarily determined by conformity and contact area between the femoral condyle and the upper surface of the PE insert. In this RP design, contact area is known to decrease with flexion greater than 35°, which predisposed to abnormal motion of the femur on PE insert (Figure 1). Under all flexion/extension gap testing conditions, PE insert rotational displacement significantly decreased with increasing knee flexion (differences ranged from 0.42 to 1.01cm, p<0.05), confirming that decreased conformity allows unintended motion to occur on the upper rather than the lower insert surface, as kinematically designed. This decrease in insert rotation was further exacerbated with eccentric medial-sided loading (differences ranged from 0.77 to 1.18cm, p<0.05). Yield torque (19.66±6.79N-m, p=0.033) and max torque (19.76±5.93N-m, p=0.014) significantly increased with increasing flexion from 0° to 60° under gap balanced conditions. Yield torque significantly decreased with greater flexion gap laxity at 60° of flexion (−24.82±5.96N-m, p=0.004). The depth of the lateral PE insert concavity (1.7–3.6mm) varied with insert size and thickness and determined femoral condylar capture. The lateral insert concavity defines a narrow margin of error in flexion/extension gap asymmetry leading to rotational insert instability, especially in smaller sized knees (size 3) where the jump height (1.7mm) is less than the insert sizing increment of 2.5mm. Conclusions. Contact area is known to decrease with flexion greater than 35° in this TKA-RP design. Flexion gap laxity further increased the risk of unintended top-side rotation of the femur on the insert, especially with increasing flexion and smaller components. In RP-TKA, in addition to medial-lateral gap symmetry and flexion-extension balance, a snug flexion gap with less than 2mm lateral laxity is critical to avoid insert instability and condylar escape with insert subluxation. For any figures or tables, please contact authors directly

Cervical total disc replacement has been in practice for years now as a viable alternative to cervical fusion in suitable cases, aspiring to preserve spinal motion and prevent adjacent segment disease. Reports are rife that neck pain emerges as an annoying feature in the early postoperative period. The facet joint appears to be the most likely source of pain. 50 patients were prospectively followed up through 5 years after having received disc replacement surgery, indicated for symptomatic soft disc herniation of the cervical spine presenting with radiculopathy. • All were skeletally mature and aged between 22 to 50. • All had failed a minimum of 6 months conservative therapy. • Up to 2 disc levels were addressed. C3 till C7 levels. • Single surgeon (first author). • NDI > 30% (15/50). • Deteriorating radicular neurology. We excluded those with degenerative trophic changes of the cervical spine, focal instability, trauma, osteoporosis, previous cervical spine surgery, previous infection, ossifying axial skeletal disease and inflammatory spondyloarthritides. The device used was an unconstrained implant with stabilizing teeth. Over the 5 years, we studied their postoperative comfort level via the Neck Disability Index (NDI) and Visual Analogue Score (VAS). Pre-operative and post-operative analysis of the sagittal axis and of involved facet joints were done. 22 patients suffered postoperative neck pain as reflected by the NDI and VAS scores. Of these, 10 reported of neck pain even 24 months after surgery. However, none were neurologically worse and all patients returned to their pre-morbid functions and were relieved of pain by 28 months. All 22 patients reported of rapid dissolution of neckache after peri-facetal injections of steroids were done under image guidance. We draw attention to the facet joint as the pain generator, triggered by inappropriate implant height, eccentric stresses via hybrid constructs, eccentric loading due to unconstrained devices and unaddressed Luschka joint degeneration. Such factors require careful selection of patients for surgery, necessitate proper pre-operative templating and call for appropriate technical solutions during surgery

Introduction. The effectiveness of patient specific instrumentation (PSI) to perform total knee arthroplasty (TKA) remains controversial. Multiple studies have been published that reveal conflicting results on the effectiveness of PSI, but no study has analyzed the contact kinematics within knee joints replaced with the use of PSI. Since a departure from normal kinematics can lead to eccentric loading, premature wear, and component loosening, studying the kinematics in patients who have undergone TKA with PSI can provide valuable insight on the ability of PSI to improve functionality and increase longevity. The goal of the present study was to compare femoral and tibial component migration (predictive of long-term loosening and revision) and contact kinematics following TKA using conventional instruments (CI) and PSI based surgical techniques. Methods. The study was designed as a prospective, randomized controlled trial of 50 patients, with 25 patients each in the PSI and CI groups, powered for radiostereometric analysis (RSA). Patients in the PSI group received an MRI and standing 3-foot x-rays to construct patient-specific cut-through surgical guides for the femur and tibia with a mechanical limb alignment. All patients received the same posterior-stabilized implant with marker beads inserted in the bone around the implants to enable RSA imaging. Patients underwent supine RSA exams at multiple time points (two and six weeks, three and six months, and one and two years). At 2 years post-op, a series of RSA radiographs were acquired at different knee flexion angles, ranging in 20° increments from 0° to 120°, to measure the tibiofemoral contact kinematics. Migrations of the femoral and tibial components were calculated using model-based RSA software. Kinematics were measured for each condyle for magnitude of excursion, contact location, and stability. Results. There were no differences (p > 0.05) between the PSI and CI groups for demographics or pre- and post-operative patient reported outcome scores. Three patients in the PSI group and seven patients in the CI group (p = 0.28) had a post-operative limb alignment outside of the neutral target (>3° varus or valgus). There was no difference in the change of tibial slope from pre- to post-operation between groups (p = 0.49). There were no differences (p > 0.05) in translations or rotations in any individual plane across all time points for either the tibial or femoral components. Maximum total point motion (MTPM) at 6 months for the tibial component was 0.54 ± 0.25 mm in the CI group and 0.51 ± 0.22 mm in the PSI group (p = 0.77), placing both groups at the low end of the “at risk” category for predicted loosening. Change in MTPM from 6 months to 1 year and again from 1 year to 2 years was <0.2 mm, indicating both groups of implants had stable fixation. Femoral component MTPM was also not different (p > 0.05) between groups. There was no significant difference between PSI and CI groups with respect to magnitude of excursion on both medial (p = 0.54) and lateral (p = 0.81) condyles. There was also no difference in contact locations on both the medial and lateral condyles (p = 0.28 to 0.91) for all angles of flexion. There was no significant difference present between PSI and CI groups when comparing the stability for both the medial (p = 0.06) and lateral (= 0.85) condyles. Condylar separation was present in 3/20 CI patients and 0/16 PSI patients (p = 0.24). Conclusion. Using the latest RSA criteria for predicting failure from early migration, the use of PSI does not provide an advantage over CI for preventing aseptic loosening. Moreover, PSI did not provide any substantial advantage over CI for TKA surgery with respect to contact kinematics

Shoulder arthroplasty is the treatment of choice for a range of degenerative diseases. However, long term follow-up suggests almost half of patients graded their treatment as unsatisfactory. Component malalignment is thought the most likely cause. The anterior anatomical neck is used as a reference for the osteotomy. The objective of the study was to analyse the cartilage/metaphyseal interface to identify reference points that may recover version accurately. Twenty-four humeri were scanned using a Microscribe digitiser and surface laser scanner. Modelling software was used to analyse the Cartilage/metaphyseal interface. The retroversion angle was calculated for the normal geometry and for the standard osteotomy. An ideal osteotomy plane was then created for each specimen and the distance from the cartilage/metaphyseal interface determined, identifying points of least deviation. The reference points were used to simulate a new osteotomy for which retroversion was calculated. The novel osteotomy and traditional osteotomy were compared to the normal geometry. The mean retroversion for the normal geometry was 18.5±9.0 degrees. The mean retroversion for the traditional osteotomy technique was 29.5±10.7 degrees, significantly different from the original (p<0.001). The mean retroversion using the novel osteotomy was 18.9±8.9 degrees and similar to the normal geometry (p=0.528). The traditional osteotomy resulted in a mean increase in retroversion of 38%. The increase in version may result in eccentric loading at the glenoid and alter rotator cuff balance. The novel osteotomy resulted in more accurate recovery of head geometry and may improve clinical outcome

The anterior portion of the anatomical neck is used as a reference for the osteotomy in shoulder arthroplasty. Resection at this level is thought to remove a segment of a sphere which can accurately be replaced with a prosthetic implant. The objective of the study was to analyse the cartilage/metaphyseal interface relative to an ideal osteotomy plane to define points of reference the may recover retroversion accurately. Data were collected from 24 humeri using a novel technique, combining data acquired using a Microscribe digitiser and surface laser scanner. Rhinocerus NURBS modelling software was used to analyse the Cartilage/metaphyseal interface. The retroversion angle was calculated for the normal geometry and for the standard osteotomy along the anterior cartilage/metaphyseal interface. An ideal osteotomy plane was then created for each specimen and the perpendicular distance from the cartilage/metaphyseal interface was determined, identifying points of least deviation. The reference points were used to simulate a new osteotomy for which retroversion was calculated. Paired t-tests were used to compare the novel osteotomy and traditional osteotomy to the normal geometry. The mean retroversion for the normal geometry was 18.5±9.0 degrees. The mean retroversion for the traditional osteotomy technique was 29.5±10.7 degrees, significantly different from the original (p< 0.001). The mean retroversion using the novel osteotomy was 18.9±8.9 degrees and similar to the normal geometry (p=0.528). The traditional osteotomy resulted in a mean increase in retroversion of 38%. The increase in version may result in eccentric load on the glenoid, an alteration to the rotator cuff balance and poor clinical outcome. The novel osteotomy based on points identified around the cartilage/metaphyseal interface that deviated least from an ideal osteotomy plane resulted in more accurate recovery of head geometry. The novel technique may improve clinical outcome. Further investigation is warranted

ECSWT has been on the medical horizon for last 30 years mainly in urology for urolithiasis and has found a parallel use in orthopaedics for various chronic soft tissue conditions like Tendoachilles tendinoses and plantar fasciitis etc. ECSWT acts a piezoelectric device releasing acoustic energy and causing micro-trauma activating cytokine mediated response stimulating local angiogenesis and tissue repair. Methodology. 56 patients were recruited for the trial after ethics approval was achieved. The diagnosis was confirmed with ultrasound scan and measuring the width of the swelling and the local hypervascularity. The cohort of the patients was randomised in groups for physiotherapy [n=23] and shockwave therapy [n= 23]. The patient groups with shockwave therapy received a 3-week treatment with typical 2000 impulses per session once a week and physiotherapy group was subjected to eccentric loading exercises. Patients were assessed at 12 week with AOFAS, VISA-A scores and repeat ultrasound scan. Results. The average age of the average age was 51 years [36- 73 years] Mean duration of symptoms prior to treatment was 25 months (range 6-60 months). AOFAS scores increased in both groups: from 64□86 in the ECSWT group and 72□79 in the physiotherapy group. VISA-A scores also increased in both groups from 39□73 in the ECSWT group and from 36□56 in the physiotherapy group. Scores were significantly higher in the ECWST group post treatment. The ultrasound scan findings suggested the tendon girth receding from 10.9 mm□9.9 mm in physiotherapy group while 9.8 mm□8.7 mm in the ECSWT group with hypervascularity decreasing from marked to mild in both groups. Statistical significance was established using SPSS 16 p < 0.001in post treatment group. Conclusion. Clinically significant improvement was found in the patients treated with ECSWT as compared to the physiotherapy sessions while radiological evidence showed parallel improvement in both the groups

Aims

The tibial component of total knee arthroplasty can either be an all-polyethylene (AP) implant or a metal-backed (MB) implant. This study aims to compare the five-year functional outcomes of AP tibial components to MB components in patients aged over 70 years. Secondary aims are to compare quality of life, implant survivorship, and cost-effectiveness.

The direction of wear in the acetabular socket has implications for the amount of debris that is generated during movement, for the magnitude of eccentric loading and for the incidence of impingement of the neck. We observed the direction of penetration with respect to a global co-ordinate system in 84 acetabular components retrieved at reoperation. The mean direction of wear relative to the open face of the sockets was found to be 37° with a range from 0° to 87°. For those values determined using the inclination of the socket on the prerevision radiograph, the mean direction of penetration in the coronal plane had a lateral, rather than a medial, component. The mean angle was 84° (SD 17°) with respect to the horizontal. The angle of penetration was found to correlate significantly with the depth, in that the lateral component became larger as the wear progressed. There was also a significant correlation between the rate of penetration and the direction of wear. Despite the theoretical advantage of penetration in the superolateral direction, i.e., along the margin of the socket, in reducing the probability of impingement of the neck, no significant correlation was seen between the angle of penetration and the period of use in vivo. This may suggest that impingement of the femoral neck on the rim of the socket may not be the dominant factor in loosening of the socket but can still be important in a few cases

Problem: The displacement of the rotation centre of the humeral head in relation to the shaft axis strongly varies individually. In order to measure the position of the pivot points of the head, the Affinis shoulder prosthesis has a double eccentric adjustment possibility that permits to adapt the head to the medial and dorsal offset. So far, such examinations took place exclusively on the anatomical preparation. This raises the question of whether the need for such a prosthetic system can be derived from the anatomical variation of the pivot points. Method: In 126 patients with an Affinis shoulder prosthesis, we calculated the individual rotation centres of the head from the position of the adjustable prosthetic cone and the eccentric position of the head. In addition, we used the Constant Score to record the clinical function. Results: We found great variation of the rotational centres. Therefore we needed the entire setting range of 12mm mediolateral and 6mm dorsoventral. The examination showed that none of the found anatomic head centres could have been reconstructed exactly with a conventional prosthesis. Prosthesis with a single eccentricity would allow correct adjustment in only 22 cases, as the adjustable rotational centres of the head are situated on a circle, which limits the setting possibilities. The Constant Score of the total group improved from 29% preoperatively to 94% after 2 years. Conclusions: The high variation of the head centres indicates the necessity of a freely adjustable system, such as in a double eccentric bearing. This is the only way that permits an optimal reconstruction of the anatomical conditions – it prevents an increased tension of the rotator cuff, reduces the eccentric loading of the glenoid and creates the prerequisites for the anatomical kinematics. The good clinical results speak for the need to observe bony balancing

Purpose of the study: Rotation of the tibial implant is an important factor for the functional outcome of total knee arthroplasty (TKA). Any rotational malposition will cause eccentric loading of the plateau. Several techniques have been recommended to avoid malposition, but none has proven superior over the others in terms of reliability or reproductibility. The landmark used to establish rotation must meet two prerequisites: easy identification and reliable representation of the anatomic rotation of the proximal tibia. This study was conducted to compare seven different techniques for landmarking used for choosing the rotation of the tibial base in TKA. Material and methods: An optoelectronic method was used to measure 50 tibia selected among a collection of 600 skeletons. A palper was used to locate 34 distinct landmarks and institute each reference system. The groups of anatomic points were reconstructed to form lines and plans depending on the comparisons to make: posterior condylar alignment (PCA), transversal alignment (TA), anterior condylar alignment (ACA), alignment of the anterior tibial tuberosity (ATT), the transmalleolar alignment (TMA), the line of the tibial crest (LTC) and a new line, the anterior distal line (ADL). The PCA was used as the reference. Results: Intra-observer variation was determined in a preliminary study using ten consecutive measurements. The standard deviation was 0.5° with a distribution of 1.8°. Angle: mean [-:internal rotation; +external rotation], standard deviation: difference between the minimum and the maximum. TA: −5.13; 9.2; 38.03; ACA: −12.81; 6.7; 41.74; ATT: 68.72; 8.6; 58.46; TMA: −22.68; 11.6; 72.84; LTC: 67.56; 10.3; 46.11; ADL: 16.61; 13.2; 74.93. Discussion: This study did not prove convincingly that any one of the tibial alignments was better than another; which demonstrates that use of a single reference is probably inappropriate to determine the rotational alignment of the tibial base for TKA. It was noted however that the anterior condylar line (mean external rotation 12.8°-SD< 7° relative to the PCA) could be pertinent for future research since this line is easily accessible and palpable, particularly during navigated surgery

Purpose: Finite element analysis can be used to assess the behaviour of loaded structures. We used this method to evaluate the influence of glenoid implant design on the behaviour of an osteoarthritic scapula. Material and methods: A 76-year-old female patient scheduled for a shoulder prosthesis underwent preoperative computed tomography of the osteoarthritic shoulder. Two polyethylene implants were evaluated: one with a triangular stem and the same prosthesis with three studs. 3D reconstruction of the glenoid cavity with the implants was then obtained and processed with the finite elements method. Three loadings were applied to the model: centred loading to reproduce the case of an ideally stable prosthesis with a normal tendinomuscular environment and excentred loading to simulate a deficient rotator cuff or prosthesis instability. Results: With centred loading, stress remained low, to the order of 7 MPa, at the stem-glenoid cavity interface. Excentered loading produced peak stress on the borders of the glenoid implants, directly under the loading zone and at the tip of the stem, at the bone-cement interface, reaching 20 MPa. The implant tended to bend in the anteroposterior direction producing strong shear forces on the posterior part of the glenoid cavity. These forces caused micromovement at the cement-bone interface. There was no significant difference between the stem and stud implants. Discussion: Eccentric loading of the glenoid implant appears to have a negative effect on long-term survival, the stress reaching levels greater than the values of cement fatigue fracture. Peak stress was situated on the posterior border of the cement layer due to the small space available between the implant the cortical bone in the posterior part of the osteoarthritic scapula. In this situation, the tip of the stem or the studs tend to come into contact with the posterior cortical of the scapula. When inserting a total shoulder prosthesis, it appears to be more important to keep in mind the geometry and the mechanical properties of the scapula than the implant design

To compare the effect of standard non-offset and offset humeral heads on early glenoid loosening. From 2002–2004 in a prospective study, 12 patients with osteoarthritis and intact rotator cuff had a TSR with an offset humeral head matching normal anatomy. Five tantalum markers were introduced into the scapula and acromion, spaced widely apart; four markers were placed in a pegged glenoid component. RSA radiographs were taken postoperatively, three, six, twelve months. The micromotion of this offset head group was compared with a baseline series of TSRs with standard non offset humeral head implants which had previously been measured over 24 months. At 24 months, the largest segment translation for the offset head group was in the anterior/posterior direction with a mean of 0.24mm, the standard head group mean was 0.61mm, t=1.3,P=0.21. Proximal/distal translation gave means of 0.51mm (standard head) and 0.17mm (offset head), t=1.3,P=0.21. Medial/lateral translation was smallest for the offset group with mean 0.16mm this is less than half the standard group mean 0.57mm and is significant, t=1.4,P=0.19. The largest rotation was anteversion/retroversion with a mean of 1.50 (offset) compared to 4.40 (standard), t=2.3, P=0.04. Varus/valgus tilt differed significantly with means 0.90 (offset) and 2.50 (standard), t=3.8,P=0.001; and finally anterior/posterior tilt had smallest means of 0.70 (offset) and 1.00 (standard), t=1.2,P=0.25. Maximum total point motion was also significantly different at 24 months, means of 0.66mm (offset) compared to 1.65mm (standard), t=2.3,P=0.04. Early migration occurs in both groups of pegged components. A principal component micromotion index illustrates the complexity of micromotion. Offset heads move significantly less than the standard type, the significant differences in MTPM movement and in rotation (varus/valgus tilt) suggest that the offset head may decrease eccentric loading

The February 2023 Research Roundup³⁶⁰ looks at: Clinical and epidemiological features of scaphoid fracture nonunion; Routine sterile glove and instrument change at the time of abdominal wound closure to prevent surgical site infection (ChEETAh); Characterization of genetic risk of end-stage knee osteoarthritis treated with total knee arthroplasty; Platelet-rich plasma or autologous blood injection for plantar fasciitis; Volume and outcomes of joint arthroplasty; The hazards of absolute belief in the p-value laid bare.

The December 2022 Shoulder & Elbow Roundup³⁶⁰ looks at: Biceps tenotomy versus soft-tissue tenodesis in females aged 60 years and older with rotator cuff tears; Resistance training combined with corticosteroid injections or tendon needling in patients with lateral elbow tendinopathy; Two-year functional outcomes of completely displaced midshaft clavicle fractures in adolescents; Patients who undergo rotator cuff repair can safely return to driving at two weeks postoperatively; Are two plates better than one? A systematic review of dual plating for acute midshaft clavicle fractures; Treatment of acute distal biceps tendon ruptures; Rotator cuff tendinopathy: disability associated with depression rather than pathology severity; Coonrad-Morrey total elbow arthroplasty implications in young patients with post-traumatic sequelae.

Injuries to the quadriceps muscle group are common in athletes performing high-speed running and kicking sports. The complex anatomy of the rectus femoris puts it at greatest risk of injury. There is variability in prognosis in the literature, with reinjury rates as high as 67% in the severe graded proximal tear. Studies have highlighted that athletes can reinjure after nonoperative management, and some benefit may be derived from surgical repair to restore function and return to sport (RTS). This injury is potentially career-threatening in the elite-level athlete, and we aim to highlight the key recent literature on interventions to restore strength and function to allow early RTS while reducing the risk of injury recurrence. This article reviews the optimal diagnostic strategies and classification of quadriceps injuries. We highlight the unique anatomy of each injury on MRI and the outcomes of both nonoperative and operative treatment, providing an evidence-based management framework for athletes.

Cite this article: Bone Joint J 2023;105-B(12):1244–1251.

Purpose: The purpose of this biomechanical study was to assess: (1) the effect of thoracic vertebral compression fracture (VCF) on kyphosis and physiologic compressive load path, and (2) the effect of balloon kyphoplasty and spinal extension on restoration of normal geometric and loading alignment. Methods: Six fresh human thoracic specimens, each consisting of three adjacent vertebrae were used. In order to create a VCF, IBTs were placed transpedicularly into the middle VB and cancellous bone was disrupted by inflation of IBTs. After cancellous bone disruption the specimens were compressed using bilateral loading cables until a fracture was observed. Fracture reduction by spinal extension, and then by balloon kyphoplasty was performed under a physiologic compressive preload of 250 N. The vertebral body heights, kyphotic deformity, and location of compressive load path were measured on video-fluoroscopy images. Results: The VCF caused anterior VB height loss of 3715%, middle-height loss of 3416%, segmental kyphosis increase of 147.0 degrees, and vertebral kyphosis increase of 135.5 degrees (p< 0.05). The compressive load path shifted anteriorly by 20% of A-P endplate width in the fractured and adjacent VBs (p=0.01). IBT inflation alone restored anterior VB height to 918.9%, middle-height to 9114%, and segmental kyphosis to within 5.65.9 degrees of pre-fracture values. The compressive load path returned posteriorly in all three VBs (p=0.00): the load path remained anterior to the pre-fracture location by 9–11% of the A-P endplate width. The extension moment fully restored the compressive load path to its pre-fracture location. Under this moment, the anterior and middle VB heights were restored to 858.6% and 749.4% of pre-fracture values, respectively. The segmental kyphosis was fully restored to its pre-fracture value; however, the middle height and kyphotic deformity of the fractured VB remained smaller than the pre-fracture values (p< 0.05). Conclusions: An anterior shift of the compressive load path in VBs adjacent to VCF can induce additional flexion moments. The eccentric loading may contribute to the increased risk of new VB fractures adjacent to an uncorrected VCF deformity. Extension moment could fully correct the segmental kyphosis but could not restore the middle height of the fractured vertebral body. Balloon kyphoplasty reduced the VCF deformity and partially restored the compressive load path to normal alignment

Aims

In this study, we aimed to explore surgical variations in the Femoral Neck System (FNS) used for stable fixation of Pauwels type III femoral neck fractures.

Introduction. Varying degrees of posterior glenoid bone loss occurs in patients with end stage osteoarthritis and can result in increased glenoid retroversion. The excessive retroversion can affect implant stability, eccentric glenoid loading, and fixation stresses. Ultimately, the goal is to correct retroversion to restore normal biomechanics of the glenohumeral joint. The objective of this study was to identify the optimal augmented glenoid design based on finite element analysis (FEA) modeling which will provide key insights into implant loosening mechanisms and stability. Materials and Methods. Two different augmented glenoid designs, posterior wedge and posterior step- were created as a computer model by a computer aided design software (CAD). These implant CAD models were created per precise manufacturers dimensions and sizes of the augmented implant designs. These implants were virtually implanted to correct 20° glenoid retroversion and the different mechanical parameters were calculated including: the glenohumeral subluxation force, relative micromotion at the bone-cement interface the glenoid, implant and cement mantle stress levels. The FEA model was then utilized to make measurements while the simulating abduction with the different implant designs. The biomechanical response parameters were compared between the models at comparable retroversion correction. Results. The model prediction of force ratio for the augmented wedge design was 0.56 and for the augmented step design was 0.87. The step design had higher force ratio than the wedge one at similar conformity settings. Micromotion was defined as a combination of three components based on different directions. The distraction measured for the wedge design was 0.05 mm and for the step component, 0.14 mm. Both implants showed a similar pattern translation wise. The greatest difference between the two implants was from the compression standpoint, where the step component showed almost three times more movement than the wedge design implant. Overall, the step design registered greater micromotion than the wedge one during abduction physiologic loading. The level of stress generated during abduction on the glenoid vault was 1.65 MPa for the wedge design and 3.78 MPa for the step one. All stress levels were found below the determined bone failure limit for the bone and polyethylene (10–20 MPa). Concerning implant stress, the results measured on the backside of the wedge and step components were 6.62 MPa and 13.25 MPa, respectively. Both components showed high level of stress level measured on the cement mantle, which exceeded the endurance limit for cement fracture (4 MPa). Discussion. The augmented glenoid is a novel surgical implant for use in with severe glenohumeral osteoarthritis. Unlike standard glenoid prosthetics, the augmented glenoid is better suited for correcting moderate to severe retroversion. Whereas a step design might provide higher glenohumeral stability, the tradeoff is higher glenoid vault, implant and cement mantle stress levels, and micromotion, indicating higher risks of implant loosening, failure or fracture over time, leading to poorer clinical outcomes and higher revision rates

Aims

Higher osteoblastic bone activity is expected in aseptic loosening and painful unicompartmental knee arthroplasty (UKA). However, insights into normal bone activity patterns after medial UKAs are lacking. The aim of this study was to identify the evolution in bone activity pattern in well-functioning medial mobile-bearing UKAs.

To investigate and compare the biomechanical characteristics of Bipedicular versus Unipedicular Vertebroplasty in cadaveric vertebra. Cadaveric single level vertebra were used to evaluate Bipedicular versus Unipedicular Vertebroplasty as an intervention for vertebral compression fractures. Cadaveric vertebra were assigned to two arms: Arm A simulated a wedge fracture followed by bipedicular cement augmentation; Arm B simulated a wedge fracture followed by unipedicular cement augmentation. Micro-CT imaging was performed to assess vertebral dimension, cement fill volumes and bone mineral density. All augmented specimens were then compressed under a static eccentric flexion load to failure. Pre and post augmentation failure load and stiffness were used to compare the two groups. Results suggest, when compared with actual failure strength, that the product of bone mineral density and endplate surface area gave a good prediction of failure strength for specimens in both arms. The mean cement volume fill of augmented vertebral bodies was 22.8% ± 7.21%. The bipedicular group showed a reduction in stiffness but an increase in post augmentation failure load of 1.09. The unipedicular group also showed a reduction in stiffness but showed a much greater increase in post augmentation failure load of 1.68. Preliminary data from this study suggests there is a significant reduction in stiffness following both bipedicular and unipedicular vertebroplasty. There is a significant increase in failure load post augmentation in the unipedicular group

In femoral locked nailing, the distal locking screws is vulnerable to mechanical failure. The stress on these screws is substantially affected by fitness of the nail in the medullary canal. In this study a closed form mathematical model based on elastic column-beam theory is developed to investigate how the nail-cortical contact which is simulated by a linear elastic foundation affects the stress of the distal locking screws. The model is comprised of a construct of a fractured femur with an intramedullay locked nail loaded by an eccentric vertical load. The stress of the locking screw is analysed as a function of the depth of the locking screw in the distal fragment under two situations: with or without nail-cortical contact in the distal fragment. In situation with nail-cortical contact, the screw stress is decreased as the length of nail-cortical contact and the depth of the screw in the distal fragment increases, but this stress contrarily increased when the nail is inserted beyond a certa

Fusion remains the standard of care and is associated with a high satisfaction rate. But.… fusion generally requires 6 weeks of restricted weight bearing or immobilization. Potential problems include 1) nonunion, 2) malunion, 3) sesamoid pain (from DJD), 4) late onset IP1 DJD. Complete joint replacement has been performed with a number of different designs since the early 1970's. The metal and poly designed implants are associated with a high failure rate, presumably from high shear loads, eccentric axial loads, poor fixation and bone stock problems. Resurfacing of both sides of the joint with a one piece silicone based crosslinked rubber {“silastic”} in rheumatoid patients appears to function better with use of metal grommets to reduce generation of particle debris and foreign body reaction. These silastic implants are still used by surgeons in select low-demand rheumatoid patients. Salvage after failure of any of these total joint replacements can be challenging because of loss of bone stock. 3 other methods are used to resurface the joint in severe OA: 1) resurfacing the proximal phalangeal side only, 2) resurfacing the metatarsal head only and 3) resurfacing the joint with and interposition arthroplasty. 1) advantage of the proximal phalangeal side resurfacing is simplicity of geometry; the disadvantage is disruption of the FHB attachment and the relative scarcity of severe cartilage damage at that side of the joint. 2) Advantage of the metatarsal head side for resurfacing is that is the typical location of the arthritic change; the disadvantage is potential interference with the sesamoid complex and bulkiness of fixation could lead to a more difficult salvage. 3) The advantage of interposition arthroplasty is the maintenance of bone stock; disadvantages include inconsistent local tissue and somewhat less predictable outcomes. In this talk I will focus primarily on the technique and results of a proximal phalangeal resurfacing approach for OA of the MTP1 joint

Aims

Patient-specific instrumentation has been shown to increase a surgeon’s precision and accuracy in placing the glenoid component in shoulder arthroplasty. There is, however, little available information about the use of patient-specific planning (PSP) tools for this operation. It is not known how these tools alter the decision-making patterns of shoulder surgeons. The aim of this study was to investigate whether PSP, when compared with the use of plain radiographs or select static CT images, influences the understanding of glenoid pathology and surgical planning.

Aims

Accurate measurement of the glenoid version is important in performing total shoulder arthroplasty (TSA). Our aim was to evaluate the Ellipse method, which involves formally defining the vertical mid-point of the glenoid prior to measuring the glenoid version and comparing it with the ‘classic’ Friedman method.

INTRODUCTION: In the spinal column, bone metastases (BM) and lesions arising from multiple myeloma (MM) can cause severe weakening of the vertebral body (VB) leading to an increased risk of fracture. 1. These vertebral fractures may induce severe pain, deformity and increased risk of neurological deficit. 2. At present, however, there is very little known about the mechanical behaviour either of the infiltrated vertebrae or that following vertebroplasty (VP). The purpose of this preliminary investigation was to evaluate (i) the mechanical behaviour of vertebrae with lesion involvement, and (ii) the effectiveness of VP with coblation. METHODS: Individual vertebrae from two spines, one with MM (n=13) and one with BM secondary to bladder cancer (n=12) were dissected free of soft tissue with the posterior elements retained. Three MM vertebrae with evidence of previous fracture were excluded. Each vertebrae was fractured under an eccentric flexion load from which fracture strength and stiffness were derived. 3. VBs were then assigned to two groups. In group 1, lesion material was removed by coblation prior to VP and in group 2, no coblation was performed prior to VP. All vertebrae were fractured post-augmentation under the same loading protocol. At each stage microCT assessments were conducted to investigate lesion morphology and cement volume/distribution. RESULTS: MM vertebrae were characterised by several small lesions, severe bone degradation and multiple compromise of the cortical wall. In contrast, large focal lesions were present in the BM vertebrae and the cortical wall generally remained intact. The initial failure strength of the MM vertebrae were significantly lower than BM vertebrae (L=2200N vs 950N, P< 0.001). A significant improvement in relative fracture strength was found post augmentation for both lesion-types (1.42 ± 0.51, P=0.0006). Coblation provided a marginally significant increase in the same parameter post-augmentation (P=0.08) and, qualitatively, improved the ease of injection. CONCLUSIONS: Bladder BM and MM vertebral lesions showed significant variations in lesion morphology, bone destruction and the level of cortical wall breach, causing significant changes in the bone fracture behaviour. Account should be taken of these differences to optimise the VP intervention in terms of cement formulation and delivery. Preliminary results suggest the current VP treatment provides significant improvements in failure strength post-fracture

Aims

Patients with a deformity of the hindfoot present a particular challenge when performing total knee arthroplasty (TKA). The literature contains little information about the relationship between TKA and hindfoot alignment. This systematic review aimed to determine from both clinical and radiological studies whether TKA would alter a preoperative hindfoot deformity and whether the outcome of TKA is affected by the presence of a postoperative hindfoot deformity.

Introduction: Realigning the foot and good ligament balancing have been recognized to be the mainstay for successful reconstruction of complex hindfoot disorders and deformities. This is particularly true for posttraumatic conditions, where deformities and scarring might be the underlying cause of foot dysfunction. For surgical reconstruction, i.e. osteotomies, arthrodeses and total ankle replacement, references are needed for restoration of the anatomy and the function. Most surprisingly to date no data is available regarding dimensions on standard X-rays of the hindfoot. The purpose of this prospective study therefore was 1) to define relevant and reproducible measures on lateral hindfoot X-rays and 2) to assess their reliability. Methods: 100 lateral view X-rays were taken. Dimensions assessed were the talar area covered by the tibia, the angle of the distal tibial joint plane to the tibial axis (tilt), the width of the tibia on the joint level, the height of the talus, the joint radius of the ankle joint and the offset of the centre of rotation from the tibial axis. Results: The tibial coverage of the talus was 88.1 degrees (SD = 0.36), the angle of the distal tibial joint plane to the tibial axis (tilt) was 83 degrees (SD 3.6), the width of the distal tibia 33.6 mm (SD = 2.4), the radius of the ankle joint 18.6 mm (SD = 4.0) with an anterior offset of the centre of rotation of 1.7 mm and the height of the talus was 28.2 mm (SD = 2.1). Conclusions: In case of symptomatic deformity any reconstruction, i.e. correcting osteotomies, ligament reconstruction, arthrodeses or arthroplasty, should aim to correct the foot in a physiological way; respecting the original dimensions of the hindfoot to achieve maximal benefit. Anterior-posterior translation of the talus may be a source of pain, restriction of motion and a cause of degenerative joint disease because of eccentric joint loading. This is also true for the height of the talus, which may have a significant impact on the hindfoot physiology. To achieve good biomechanical function, the positioning of the talus in relation to the tibia needs to be planned carefully prior to surgery. Poor coverage of the talus by the tibia and too much tilt of the distal tibia lead to higher joint forces and may be the cause of instability. Surgical procedures may fail if this is not recognized preoperatively. Several easily accessible measures on X-rays were found to be reliable to describe the hind-foot, as only small variation was found on the evaluated X-rays. If reconstruction of the hindfoot is required, care should be taken to identify the physiological joint geometry

Objectives

The primary objective of this study was to compare accuracy in restoring the native centre of hip rotation in patients undergoing conventional manual total hip arthroplasty (THA) versus robotic-arm assisted THA. Secondary objectives were to determine differences between these treatment techniques for THA in achieving the planned combined offset, component inclination, component version, and leg-length correction.

Aims

The Walch Type C dysplastic glenoid is characterized by excessive retroversion. This anatomical study describes its morphology.

Aims

Controversy about the use of an anatomical total shoulder arthroplasty (aTSA) in young arthritic patients relates to which is the ideal form of fixation for the glenoid component: cemented or cementless. This study aimed to evaluate implant survival of aTSA when used in patients aged < 60 years with primary glenohumeral osteoarthritis (OA), and to compare the survival of cemented all-polyethylene and cementless metal-backed glenoid components.

In recent years, the plantaris tendon has been implicated in the development of chronic painful mid-portion Achilles tendinopathy. In some cases, a thickened plantaris tendon is closely associated with the Achilles tendon, and surgical excision of the plantaris tendon has been reported to be curative in patients who have not derived benefit following conservative treatment and surgical interventions.

The aim of this review is to outline the basic aspects of, and the recent research findings, related to the plantaris tendon, covering anatomical and clinical studies including those dealing with histology, imaging and treatment.

Cite this article: Bone Joint J 2016;98-B:1312–19.

Objectives

Secondary fracture healing is strongly influenced by the stiffness of the bone-fixator system. Biomechanical tests are extensively used to investigate stiffness and strength of fixation devices. The stiffness values reported in the literature for locked plating, however, vary by three orders of magnitude. The aim of this study was to examine the influence that the method of restraint and load application has on the stiffness produced, the strain distribution within the bone, and the stresses in the implant for locking plate constructs.

The February 2014 Foot & Ankle Roundup³⁶⁰ looks at: optimal medial malleolar fixation; resurfacing in the talus; predicting outcome in mobility ankles; whether mal-aligned ankles can be successfully replaced; cartilage colonisation in bipolar ankle grafts; CTs and proof of fusion; recalcitrant Achilles tendinopathy; and recurrent fifth metatarsal stress fractures.

The October 2014 Shoulder & Elbow Roundup³⁶⁰ looks at: PRP is not effective in tennis elbow; eccentric physiotherapy effective in subacromial pain; dexamethasone in shoulder surgery; arthroscopic remplissage for engaging Hill-Sach’s lesions; a consistent approach to subacromial impingement; delay in fixation of proximal humeral fractures detrimental to outcomes.

Aims

One goal of total hip arthroplasty is to restore normal hip anatomy. The aim of this study was to compare displacement of the centre of rotation (COR) using a standard reaming technique with a technique in which the acetabulum was reamed immediately peripherally and referenced off the rim.

Patellar instability most frequently presents during adolescence. Congenital and infantile dislocation of the patella is a distinct entity from adolescent instability and measurable abnormalities may be present at birth. In the normal patellofemoral joint an increase in quadriceps angle and patellar height are matched by an increase in trochlear depth as the joint matures. Adolescent instability may herald a lifelong condition leading to chronic disability and arthritis.

Restoring normal anatomy by trochleoplasty, tibial tubercle transfer or medial patellofemoral ligament (MPFL) reconstruction in the young adult prevents further instability. Although these techniques are proven in the young adult, they may cause growth arrest and deformity where the physis is open. A vigorous non-operative strategy may permit delay of surgery until growth is complete. Where non-operative treatment has failed a modified MPFL reconstruction may be performed to maintain stability until physeal closure permits anatomical reconstruction. If significant growth remains an extraosseous reconstruction of the MPFL may impart the lowest risk to the physis. If minor growth remains image intensifier guided placement of femoral intraosseous fixation may impart a small, but acceptable, risk to the physis.

This paper presents and discusses the literature relating to adolescent instability and provides a framework for management of these patients.

Cite this article: Bone Joint J 2017;99-B:159–70.