In this biomechanical study of isolated porcine C2 vertebrae, antero-posterior forces were applied to potted specimens. Bipedicular fractures were generated in 25.4% of fifty-nine specimens (others fractured mostly through laminae). Bipedicular fractures were subsequently fixed under direct vision with trans-pedicular lag screws. These fixed specimens were then tested again. The mean ultimate tensile strength of the construct was 27.1% compared to the native bone’s fracture strength in the same specimen. This is a good model for hangman’s fracture, and is relevant to newer constructs that utilize C2 pedicle screws as part of a larger instrumentation procedure.

Hangman’s fracture rarely needs internal fixation. However, if fixation is indicated the fracture can sometimes be directly fixed with trans-pedicular screws rather than fusing C1-C2 and committing to a great loss of neck range of motion. To our knowledge, the actual pullout strength of pedicle screws in C2 is previously unreported. Hence, we developed a laboratory model of hangman’s fracture by applying antero-posterior tensile force in fifty-nine porcine specimens that were stripped of soft tissues. The failure strength of the bone averaged approximately 3200 N, and subsequent fixation averaged to 27.1% of this value. Regardless of pre-hoc expectations, these values indicate that the screw purchase is strong enough to consider continued use of the procedure in repair of hangman’s fracture, fixation to C2 of multi-level constructs, and so forth. Multiple anterior and posterior screw procedures have been tested in the past, but to our knowledge the pullout strength of C2 pedicle screws has not been examined. Because the usage of C2 pedicle screws is growing in popularity, this biomechanical information is pertinent to work in traumatic, degenerative, and reconstructive procedures. Some limitations of the present study are that the specimens were porcine rather than human, and that only fixation to single vertebrae was examined.

Funding: Dr Kaspar holds academic research grants from McMaster University and from The Physicians’ Services Incorporated (PSI) Foundation, the former of which was used to finance this project. There are no commercial grants or conflicts of interest.

Failed open reduction internal fixation (ORIF) of the proximal femur can render patients severely disabled. This study analyzed the short-term functional results and complications of total hip arthroplasty (THA) for complications of ORIF of the proximal femur. Using the Hamilton Arthroplasty Database, thirty-six patients treated with a THA for complications of ORIF of the proximal femur were compared to a matched cohort. Analysis showed that THA for complications of ORIF of the proximal femur is a successful procedure despite increased intraoperative difficulty that results in comparatively lower short-term Harris Hip Scores. No statistically significant differences in intraoperative or postoperative complications were noted.

Open reduction internal fixation (ORIF) of the proximal femur is a common, successful orthopedic procedure. However, failed ORIF of the proximal femur can render patients severely disabled. The purpose of this study is to analyze and compare the short-term functional results and complications of total hip arthroplasty (THA) for complications of ORIF of the proximal femur.

After ethics approval, the Hamilton Arthroplasty Registry, a prospective database, was used to identify thirty-seven patients treated with THA for complications of ORIF of the proximal femur. From September 1998 to the present a group consisting of sixteen males and twenty females, with a mean age of sixty-seven, were matched to a cohort of patients treated with a primary THA. Using Wilcoxon Test and Chi-Square Tests, the two groups were compared (p< 0.05).

Initially, ORIF was used to treat thirty-six patients for proximal femur fracture. The mean follow-up was 13.5 months. The experimental group had a significantly lower (p=0.035) Harris Hip Score at the one year follow-up, however both groups showed a significant improvement from preoperative scores (p=0.0001). A significant difference was noted between the two groups in estimated blood loss (p=0.01) and operative time (p=0.01). There was no significant difference in complication rate.

THA for complications of ORIF of the proximal femur is a successful procedure improving patient’s pain and functional status. This is a more complicated procedure than primary THA, at times requiring the use of a revision stem, which results in significantly lower Harris Hip Scores. Nonetheless, there appears to be no comparative increase in short-term complications.

There has never been a study of whether intra-articular steroid injections of arthritic hips can alter the outcomes of subsequent arthritis management, particularly total hip arthroplasty (THA). In this study forty patients with a history of steroid injection of the hip and subsequent THA are examined retrospectively for infections, revisions, and prospectively-gathered hip scores, as compared to matched non-steroid controls. The steroid group had an increased incidence of pain, infectious workup under usual care, and two revisions for deep infection within three years. We suggest that steroid injections of hips should be avoided in patients who are candidates for THA.

Despite the lack of demonstrated efficacy of intra-articular steroid injections for hip arthritis, the procedure is often utilized for diagnostic differentiation from spine pain, and attempted therapeutic management of painful hip arthritis. However, in the era of total hip arthroplasty (THA) the safety of this practice must be evaluated in the context of whether the injections pose any potential for complicating subsequent surgery, particularly with regard to infection. In this study, forty patients who underwent THA and had a history of previous steroid injection were compared retrospectively to forty carefully-matched patients who underwent THA in the same time period but had no history of prior steroid injection. Outcome measures included whether there was a septic workup under usual care, and this occurred in 20% of steroid patients within the first thirty-six months post-THA, as opposed to 0% in the controls. Furthermore, in a detailed analysis of Harris and Oxford scores, there was in the steroid group a higher incidence of night pain, increased severity of pain, and reduced function with activities of daily living at one year. There were two revisions for deep infection in the steroid group, and one revision for dislocation in each of the steroid and control groups. Pending the completion of the study, we provisionally suggest that steroid injection of hips may be ill-advised in a patient who will be a candidate for THA in the future. This suggestion is based primarily on the incidence of pain and infectious complications in the first postoperative year.

Funding Dr Kaspar holds academic research grants from McMaster University and from The Physicians’ Services Incorporated (PSI) Foundation, the latter of which was used to finance this study and the continuation thereof. There are no commercial grants or conflicts of interest.

Introduction and Aims: Intra-articular steroid hip injection (IASHI) has been extensively administered for painful hip arthritis since the 1950s, but with advances in medical and surgical management, its role is less certain today. There is very little published data on the utility or prescribing patterns of IASHI.

Method: A questionnaire seeking expert opinions on IASHI was developed and distributed to practising Ontario-based members of the Canadian Orthopaedic Association. Initial phone calls identified those who perform hip replacements, and subsequent faxed forms had a 73% response rate (99 surgeons). We systematically describe the current practices and expert opinions of 99 hip surgeons, on the use of IASHI, focusing on indications, current usage, and complications.

Results: Only 56% of surgeons felt that IASHI was actually useful therapeutically, though four in five surgeons cited the usefulness of hip injection for differentiating hip-spine co-morbidity in diagnostically challenging patients. Therapeutic benefit from IASHI was perceived to be poor, with 72% of surgeons estimating that between zero and 60% of their patients achieved any benefit at all from the injections, with duration of benefit uniformly estimated as being between zero and six months. Infection rates were considered to be less than 2% by most surgeons. One quarter of the surgeons felt that IASHI accelerates arthritis progression, most of whom had stated that it would be no great loss if IASHI was no longer available. Nineteen percent of the surgeons believed that there may be increased infection rate of THA after IASHI, and this was associated with lower numbers of IASHI ordered per year, compared to those who did not feel that infection rates would increase. The opinions of this large group of experts is consistent with efficacy studies, and forms a context for our ongoing studies of infected hip arthroplasty post-IASHI.

Conclusion: Opinions were mixed, with substantial numbers of surgeons stating that the procedure is not therapeutically helpful, may accelerate arthritis progression, or may increase infections after subsequent total hip arthroplasty. This information provides a systematic collection of expert opinions, as well as a context for forthcoming studies on effectiveness and complications.

Introduction and Aims: Intra-articular steroid hip injection (IASHI) for osteoarthritis of the hip has not been well studied. The immunosuppressive nature of steroids may be hypothesised to interfere with asepsis in subsequent total hip arthroplasty (THA). We evaluate the infectious complications and functional outcomes of THA performed in patients who previously received IASHI.

Method: This is a retrospective cohort study of functional outcomes (Harris and Oxford hip scores), and infectious complications in the first year following THA, in patients without (n=40 controls) or with (n=40) a history of ipsilateral IASHI. Functional scores had been compiled in our database, at one tertiary care centre, and infectious complications (wound infection, deep infection, work-up with bone scans, revision surgery) were retrospectively reviewed from hospital records.

Results: The IASHI group had worse post-THA function (p=0.0008 ANOVA for Oxford functional hip scores across time, with mean one-year scores being worse by seven points out of 60). In the IASHI group there were five revision surgeries, four of which were for deep infection of the hip replacement (10%, versus 0% in controls, versus 1.02% in our database of 979 THA primaries, p < 0.001 by Log-Rank testing of Kaplan-Meier survivor-ship analysis). Additionally, each group had two superficial wound infections. Six additional IASHI patients underwent infectious work-ups for ongoing hip problems (compared to one patient worked-up in the control group). The total rate of culture-proven infection (either superficial or deep), or problems leading to negative infectious work-up, was 12/40 (steroid, 30%) versus 3/40 (control, 7.5%, p = 0.010 by Fisher’s Exact test).

Conclusion: IASHI should now be considered as relatively contra-indicated in patients who are (or will become) candidates for THA. IASHI appears to compromise the functional results of subsequent THA, with much higher infection and revision rates. We suggest a multi-centre review of infected THA post-IASHI.

Introduction and Aims: Although PD has characteristic findings and stages of progression, neither the nature of operative spine problems occurring in patients with PD, nor their peri-operative complications, have been presented previously.

Method: In this retrospective observational case series, we describe the nature of operative spine problems in patients with Parkinson’s disease (PD), and evaluate the incidence and types of peri-operative complications in spine surgery for patients with PD. A retrospective chart review was performed on 24 consecutive PD patients undergoing spine surgery in a six-year span at one institution. Nineteen were first surgeries, and five were first seen as failed back syndrome from surgery done elsewhere.

Results: The mean patient age was 69 years. Spinal stenosis (10 patients) and cervical myelopathy (4 patients) were the predominant pre-operative diagnoses for the primary surgeries, with three patients operated upon for kyphoscoliosis (16%) and two for other conditions. Minor or transient complications were common, including delirium, arrhythmia, deep vein thrombosis, and dural tear; there were also two significant PD-specific complications, including aspiration pneumonia and global motor paresis post-operatively. Four of 19 primary cases were revised for recurrent stenosis (two patients) or pseudarthrosis (two patients). The overall number of poor patient-reported outcomes was only two of 14 primary cases (five patients had inadequate outcome measures) and zero of seven revisions (two had inadequate outcome measures), at a mean follow-up of 19 months.

Conclusion: Symptoms and functional deficits of spinal disease were often masked by PD, posing diagnostic difficulty. However, outcomes and complications of spine surgery were similar to those of non-PD patients at the same institution. Spine symptoms improved concomitantly with successful surgery unless the PD progressed or significant complications ensued.

Introduction and Aims: Although cortical hypertrophy (CH) in total hip arthroplasty (THA) has been associated with thigh pain and loose femoral stems, its presence has been variable in the literature, and it is an implant-specific phenomenon. The relationship of bony change to clinical outcome has not previously been examined in ceramic THA.

Method: Hardened-bearing surfaces such as ceramics have the potential for altered patterns of force transmission into the femoral stem-bone interface, and as such could lead to altered bone remodelling. We investigate here the incidence and magnitude of CH at the Gruen zones, about the femoral stem of THA utilising ceramic-on-ceramic bearing surfaces without (n=36) or with (n=4) cement, and metal-polyethylene bearing surfaces without (n=40) or with (n=40) cement. Using multifactorial analysis, we examined the relationship of implant alignment, Harris and Oxford hip scores, and bone remodelling parameters.

Results: In this study of 120 patients, the hip scores and x-rays are examined in the first year after total hip arthroplasty (THA), in order to evaluate bone remodelling in relation to clinical outcomes. Ceramics had the highest incidence (25%) and mean size (1.5 mm) of CH, followed by metal-polyethylene (17%, < 1 mm). No cemented implants exhibited CH. There was no significant relationship of bone remodelling to one-year hip scores, although there were significantly reduced pain scores in cases that exhibited endosteal remodelling at one year. CH in ceramic hips appears to be a mechanical phenomenon that is not associated with pain, varus drift, subsidence, or altered clinical outcome. Cement may buffer the stresses seen by the femur, and hence the stimulus for CH appears to be simply mechanical, and is increased with hardened-bearing surfaces.

Conclusion: CH was more common in ceramic THA than metal-polyethylene, but was not associated with increased thigh pain or altered function. CH did not occur when cement was used, and as such we argue for a mechanical origin of the phenomenon, via altered load transmission into the femur through hardened-bearing surfaces.

Introduction and Aims: Clinical studies report successful treatment of hangman’s fractures by direct screw repair followed by a collar post-operatively. However, to date there has not been a biomechanical analysis of failure strength of direct lag screw fixation of hangman’s fracture, relative to the strength of the intact specimens.

Method: This repeated measures biomechanical study evaluates the tensile force required to cause bipedicular (hangman’s) fractures in isolated porcine C2 specimens, and the subsequent force to failure after direct fracture repair with bipedicular lag screws. Of 60 mounted porcine C2 specimens subjected to tensile antero-posterior force, hangman’s fracture occurred in 15 cases, 12 of which were fixed with bipedicular 4.0 mm lag screws. These fixed specimens were re-tested to failure in the same manner.

Results: Most specimens had laminar fractures after application of tensile force, with 15 of 60 (25.0%) exhibiting bipedicular fractures. The force to bipedicular failure was 3259.1 + 148.5 N (mean + SEM). After screw fixation, the force to failure of the same specimens was 882.0 + 108.5 N (mean + SEM), or 27.3% of the intact bone.

Conclusion: The pullout strength was substantial (882 N), although the relative strength of fixation was only 27.3% of the fracture strength exhibited by the intact specimens. We discuss the findings in relation to previous studies. This is the first study to examine screw pull-out forces after direct repair of hangman’s fracture. One or more of the authors are receiving or have received material benefits or support from a commercial source.

Immunosuppression following intra-articular injections of steroid into the hip may interfere with asepsis in a subsequent total hip arthroplasty (THA). We have undertaken a retrospective, matched, cohort study of infective complications after THA, in 40 patients who had received such an injection and 40 who had not.

In the injection group there were five revisions, four of which were for deep infection. There were none in the matched group. The overall rate of revision in our database of 979 primary THAs was 1.02%. Six additional patients who had received injections underwent investigation for infection because of persistent problems in the hip as compared with one in the control group.

In this study, 40 patients who underwent total hip arthroplasty (THA) and had a history of previous steroid injections were compared retrospectively with 40 carefully matched patients who underwent THA in the same period but had never received steroid injections. The development of sepsis under standard care was one of the outcome measures. This occurred in 20% of steroid patients within the first 36 months after THA, compared to 0% in the control group. Further, in a detailed analysis of Harris and Oxford scores, patients treated with steroid had a higher incidence of night pain, more severe pain, and greater loss of function in activities of daily living at one year. There were two revisions for deep infection in the steroid and control groups.

Based on the incidence of pain and infectious complications in the first postoperative year, and pending completion of the study, we provisionally suggest that steroid injection of hips may be ill advised in patients who are likely candidates for future THA.