The National Hip Fracture Database (NHFD) is a clinically led web based audit used to inform national policy guidelines. The aim of this audit was to establish the accuracy of completion of NHFD v13.0 theatre collection sheets, identify common pitfalls and areas of good practice, whilst raising awareness of the importance of accuracy of this data and the manner in which it reflects performance of CAH Trauma & Orthopaedic unit in relation to national guidelines. Our aim was to improve completion up to >80% by the operating surgeon and improve overall accuracy.

The methodology within both cycles of the audit were identical. It involved reviewing the NHFD V13.0 completed by the operating surgeon and cross-checking their accuracy against clinical notes, operation notes, imaging, anaesthetic charts and A&E admission assessment.

Following completion of cycle 1 these results were presented, and education surrounding V13.0 was provided, at the monthly trust audit meeting. At this point we introduced a sticker onto the pre-operative checklist for Hip fractures. This included time of admission and reason for delay. We then completed a re-audit.

Cycle-1 included 25 operations, 56% (n=14) had a completed V13.0 form. Of these 21% (n=3) were deemed to be 100% accurate. Cycle-2 included 31 operations (between April – June 21) 81% (n=25) had a completed intra-operative from and showed an increase in accuracy to 56% (n=14)

Through raising awareness, education and our interventions we have seen a significant improvement in the completion and accuracy of v13.0. Although 100% accuracy was not achieved its clear that education and intervention will improve compliance over time.

Through the interventions that we have implemented we have shown that it is possible to improve completion and accuracy of the NHFD V13.0 theatre collection sheet locally and feel this could be implemented nationally.

Introduction This is the largest analysis to date of any retrieved porous ingrowth disk replacement prostheses. In distinction to prior reports of retrieved implants which were conducted like “airplane crash” type pseudoanalyses, in this series the position of the components was known in vivo prior to implant removal. The digitized radiographs were used to determine if the components were in ideal, suboptimal, or poor position. There were thirty cervical disk replacements and thirty-eight lumbar disk replacements which comprised the basis of this analysis.

Methods Quantitative histomorphometry, microradiography, and histology were performed on all 68 vertebral endplates. Scanning electron microscopy was performed on ten. All 24 caprine model, 34 non-human primates, and 10 human explants with titanium calcium phosphate porous ingrowth surface were manufactured by the same vendor, D.O.T., which provides the same porous ingrowth coating for several FDA approved total hip replacements. Group I – Ideal placement, was defined as Charité or PCM Artificial Disc replacement within 3 mm of exact central axis in both the coronal planes and mid-sagittal planes (2 mm posterior to the midpoint of the vertebral body in the sagittal plane for Charité only).The endplates of the prosthesis also had to be within 5 degrees of angulation of the bony end-plate or within 5 degrees of angulation of the perpendicular axis of the vertebral body. Group II – Suboptimal placement, was defined as Charité or PCM Artificial Disc placement from 3 mm to 5 mm from exact central placement in at least one axis In addition the prosthetic endplate had to be from 5 degrees to 10 degrees of perpendicular vertebral body orientation. Group III – Poor placement, was defined as greater than 5 mm from exact central placement in at least one axis or the endplate was greater than 10 degrees off angle. Three separate observers judged the measurements of axes and made a determination of prosthesis placement after correction for magnification error.

Results The mean length of time in biologic conditions to monitor reabsorption and incorporation of the ingrowth surface was a mean of 10.5 months (range 6 to 33 months). This is the first study finding a correlation between the position of the components and amount of successful bony ingrowth. A representative group was: Ideal 50.9 +/− 13 % ingrowth, Suboptimal placement, 49.3 +/−18 % ingrowth, and Poor, 33.0 +/− 29.2 % ingrowth. There was trend but not statistically significant (F= 1.78, p = .186). The mean ingrowth of prostheses in poor and suboptimal position (defined by axis off by 3mm in either AP or Lateral plane) was 43.2 %. Whereas the mean ingrowth of prostheses inserted in “ideal position” within 3 mm of the optimal prosthesis axis in both planes was 46.4 %. The definition of successful biologic ingrowth in the extremities for total joint replacement is porous ingrowth over 30 %, which was achieved in 58 / 68 (85.3 %) of vertebral endplates.

Discussion The porous ingrowth TiCaP bioactive technology permits osseointegration despite non-ideal positioning. The surgeon’s technical shortcomings to place the prosthesis in ideal position were more than compensated for as 85.3 % of the components were successfully ingrown and biologically fixed to the vertebral trabeculae at the time of explantation. There were no cases of osteolysis or biomaterial failure encountered in this retrieval study.

Introduction This in-vitro biomechanical study was undertaken to compare the multi-directional flexibility kinematics of single versus multi-level lumbar Charité reconstructions and determine the optimal biomechanical method for surgical revision – posterior instrumentation alone or circumferential spinal arthrodesis.

Methods A total of seven human cadaveric lumbosacral spines (L1 to Sacrum) were utilized in this investigation and biomechanically evaluated under the following L4-L5 reconstruction conditions: 1) Intact Spine; 2) Diskectomy Alone, 3) Charité, 4) Charité + Pedicle Screws, 5) Two Level Charité (L4-S1), 6) Two Level Charité + Pedicle Screws (L4-S1), 7) Charité L4-L5 with Pedicle Screws and Femoral Ring Allograft (L5-S1) and 8) Pedicle Screws and Femoral Ring Allograft (L4-S1). Multi-directional flexibility testing utilized the Panjabi Hybrid Testing protocol, which includes pure moments for the intact condition with the overall spinal motion replicated under displacement control for subsequent reconstructions. Hence, changes in adjacent level kinematics can be obtained compared to pure moment testing strategies. Unconstrained intact moments of ±7Nm were used for axial rotation, flexion-extension and lateral bending testing, with quantification of the operative and adjacent level range of motion (ROM) and neutral zone (NZ). All data was normalized to the intact spine condition.

Results In axial rotation, single and two level Charité reconstructions produced significantly more motion than pedicle screw constructs combined with the Charité or femoral ring allograft (p< 0.05). There were no differences between the Charité augmented with pedicle screws or pedicle screws with femoral ring allograft (p> 0.05). Similar trends were observed under flexion-extension and lateral bending conditions with the Charité reconstructions demonstrating no significant differences compared to the intact spine (p> 0.05). However, the Charité combined with pedicle screws or pedicle screws with femoral ring allograft significantly reduced motion at the operative level compared to the Charité reconstruction (p< 0.05). The most pronounced changes in adjacent level kinematics were observed at the inferior level. The addition of pedicle screw fixation, in all cases, increased segmental motion at the inferior adjacent level (L5-S1) compared to the intact and Charité reconstruction groups (p< 0.05).

Discussion Single and two level total disc arthroplasty using the Charité device preserved segmental motion at the operative and adjacent levels compared to pedicle screw stabilization constructs. In terms of revision strategies, posterior pedicle screw reconstruction combined with an existing Charité is not statistically different from pedicle screws combined with femoral ring allograft. As we enter an era of total disc replacement and the impending necessity for surgical revision, the current study provides a biomechanical basis for posterior re-stabilization alone in lieu of combined anteroposterior revision.

Introduction The current study was undertaken to investigate the biomechanical and biologic in-growth characteristics of the Porous Coated Motion™ cervical disc prosthesis following a six and twelve-month implant duration using an in-vivo caprine model.

Methods Twelve mature Nubian goats were divided into two groups based on post-operative survival periods of six (n=6) and twelve months (n=6). Using an anterior surgical approach, a complete diskectomy was performed at the C3-C4, followed by implantation of the Porous Coated Motion™ device. Functional outcomes of the disc prosthesis were based on computed tomography (CT), multi-directional flexibility testing, undecalcifed histology, histomorphometry and immunocytochemical analyses.

Results There was no evidence of prosthesis loosening, neurologic or vascular complications. CT scans demonstrated the ability to image and assess the cervical spinal canal for the presence of compressive pathology in the area of the CoCrMo prosthesis. Multi-directional flexibility testing indicated no differences in full range of intervertebral motion between the disc prosthesis and non-operative controls (n=7) under axial rotation or lateral bending conditions (p> 0.05). Flexion-extension produced significantly more motion for the intact spine compared to the cervical disc prosthesis (p< 0.05). Based on immunohistochemical and histologic analysis, there was no evidence of particulate debris, cytokines or cellular apoptosis within the local tissues overlying the operative site or systemic tissues. Moreover, review of the spinal cord at the operative levels indicated no evidence of cord lesions, inflammatory reaction, wear particles or significant pathologic changes in any treatment. Histomorphometric analysis at the metal-bone interface indicated the mean trabecular ingrowth of 40.5±24.4% at six-months and 58.65% ± 28.04 at twelve months.

Discussion All twelve goats undergoing cervical disc replacement had no evidence of implant loosening or inflammatory reactions from particulate wear debris. Segmental intervertebral motion was preserved based on multi-directional flexibility testing. The TiCaP porous ingrowth surface provided some immediate advantages for endplate osseointegration as there was no evidence of implant subluxation, despite immediate post-operative unrestricted cervical activity. Following cervical disc replacement, histological osseointegration at the implant-bone interface is possible, while preserving segmental motion.

Introduction Total disc arthroplasty serves as the next frontier in the surgical management of intervertebral discogenic pathology. As we move from an era of interbody spinal arthrodesis to one in which segmental motion is preserved, this promising new technology offers increasing clinical and research challenges in the areas of spinal kinematics, histologic osseointegration at the prosthetic-bone interface and the effects of particulate wear debris. The primary focus of this paper is to provide a methodological basis to investigate the spinal kinematics, histologic osseointegration and particulate wear debris following total disc replacement arthroplasty using in-vitro and in-vivo models.

Methods Part I: Using an in-vitro cadaveric model, multidirectional flexibility testing evaluated the functional unit kinematics under the following L4-L5 reconstruction conditions: 1) Intact Spine; 2) Charitè Disc Prosthesis; 3) BAK Cages; 4) BAK Cages + ISOLA pedicle screw/rod fixation (anteroposterior). Part II: A total of twenty-seven mature baboons (n=27, Papio cynocephalus) underwent L5-L6 total disk replacement procedures to investigate the biomechanical, histochemical, and biologic ingrowth characteristics of two different lumbar disc prostheses – AcroFlex and Charite’ – for total disc replacement arthroplasty. Functional spinal unit fusion status was assessed using radiographic analysis, biomechanical testing, undecalcified histopathologic and histomorphometric analyses. Part III: Using a total of Fifty New Zealand White rabbits, the current study served to quantify the neural and systemic tissue histopathological response, following epidural application of four different types of spinal instrumentation particulate wear debris – 1) Sham (control) (n=10), 2) Stainless Steel 316LVM (n=10), 3) Titanium Alloy Ti-6AL-4V (n=10), 4) Cobalt Chrome Alloy (n=10) and 5) Ultrahigh molecular weight polyethylene (UHMWPE) (n=10).

Results In-vitro multi-directional flexibility testing demonstrates the operative and adjacent level motion preserving properties of total disc arthroplasty versus interbody arthrodesis cages and pedicle screw spinal instrumentation. To this end, disc replacement preserves the normal centrode or locus of intervertebral rotation at the operative and adjacent intervertebral spinal levels compared to conventional stabilization implants. Based on non-human primate modeling in the current studies, porous titanium interface surfaces afforded the greatest percentage of trabecular in-growth at the prosthesis-end-plate interface. In-vivo segmental motion under multi-directional testing was preserved with the Charité device and slightly diminished with the AcroFlex implants. The porous ingrowth coverage at the bone-metal interface was more favorable for total disk replacement (range 40 to 50%) compared to that reported for cementless total joint components in the appendicular skeleton (range 10 to 30%). Direct epidural application of spinal instrumentation particulate wear debris elicits a chronic histiocytic reaction localized primarily within the epidural fibrous layers. Moreover, particles have the capacity to diffuse intrathecally, eliciting a macrophage / cytokine response within the epidural tissues, cerebrospinal fluid and spinal cord itself. Overall, based on the post-operative time periods evaluated, there was no evidence of an acute neural or systemic histopathologic response to the materials included in the current project.

Conclusions The implementation of dynamic spinal stabilization systems for fusionless correction of spinal deformity, dynamic posterior stabilization and total disc replacement arthroplasty necessitates improved understanding with regard to spinal kinematics, patterns / mechanisms of histologic osseointegration and the neurohistopathologic response to particulate wear debris. Collectively, the current studies provide a methodological basis to comprehensively evaluate these three areas.

Introduction: A prospective randomized study of artifical disc replacement vs. lumbar fusion for one-level disc pathology with 2 year minimum follow-up was completed in compliance with a U.S. FDA protocol.

Methods: A total of 15 investigational sites enrolled 375 subjects with a randomization in a 2:1 ratio. Of the 375, 205 were randomized to receive the Charité artificial disc, and 99 were randomized to receive anterior lumbar interbody fusion with BAK cages. An additional group of 71 patients received the Charité disc as “training cases” prior to beginning randomization. Clinical outcome measures included VAS, Oswestry Disability Index, and SF-36 Healthy Surveys. A total of 6,900 radiographs were digitized throughout the 24 month treatment interval. The 276 disc replacement patients were allocated into one of three groups based on radiographic technical paramenters-- Group I – Ideal, defined as Charité disc placement within 3 mm of ideal in both planes. Coronal plane = AP radiograph = midline or within 3 mm of midline. Mid-Sagittal plane = Lateral radiograph = 2mm posterior to middle of vertebral body or within 3mm of this axis. Group II —Suboptimal (not ideal) and Group III – Poor.

Results: The Charité prosthesis was significantly more effective than BAK in restoring the height of the collapsed disk space (p < 0.001). In Charité cases, the mean initial disc space height at the L5-S1 operative level was 5.2 mm +/− 1.44 (Std Dev) and increased to a mean of 13.5 mm +/− 1.18 (Std Dev). For BAK, the initial disc space height was 5.9.mm +/− 1.74 and increased to an immediate post-operative disk space height of 11.9 mm +/− 2.07. There was less subsidence with the Charite disk replacement than the BAK control at 2 years (p < 0.001). Of the 276 subject radiographs analysed with Charité disc replacement, 83% were classified as Group I, 11% as Group II, and 6% as Group III.

The mean Oswestry Disability Index scores at 2 years correlated with technical accuracy in placement of the prosthesis: Group I – 24.1; Group II – 30.3; and Group III – 36.3 (p < .05). The Mean VAS scores at 2 years correlated with technical accuracy in placement of the prosthesis: Group I – 28.3; Group II – 35.4; and Group III – 48.4 (p = 0.016). The mean flexion/extension range of motion and prosthesis function also correlated with device placement: Group I – 7.12 +/− 4.06 degrees; Group II – 7.47 +/− 4.41 degrees; and Group III – 3.15 +/− 3.51 degrees (p = 0.003).

Discussion: The surgical technical accuracy of Charité artificial disc placement correlated with clinical outcome, range of motion, and device functionality at 2 years. The Charité Lumbar Disk replacement proved to be a successful alternative to traditional lumbar fusion in every parameter. The results from this U.S. Investigational study confirm that proper placement of the Charité artificial disc improves clinical and radiological outcomes.