The optimal timing of when to perform manipulation under anesthesia (MUA) for stiffness following total knee arthroplasty (TKA) is unclear. This study aimed to identify the risk factors for MUA following primary TKA and whether performing an “early” MUA within 3 months results in a greater improvement in range of motion. Primary TKAs performed between January 2013 and December 2018 at three tertiary New Zealand hospitals were reviewed. International Classification of Diseases discharge coding was used to identify patients who underwent an MUA. Multivariate Cox regression was performed to identify patient and surgical risk factors for MUA. Pre- and post-MUA knee flexion angles were identified through manual review of operation notes. Multivariate linear regression was performed to compare the mean flexion angles pre- and post-MUA, as well as the mean gain in flexion, between patients undergoing “early” (<3 months) versus “late” MUA (>3 months). 7386 primary TKAs were analyzed in which 131 underwent subsequent MUA (1.8%). Patients aged <65 years were two times more likely to undergo MUA compared to patients aged ≥65 years (2.5% versus 1.3%, adjusted hazard ratio = 2.1, p<0.001). Gender, body mass index, patient comorbidities or a history of cancer were not associated with the risk of MUA. There was no difference in the final post-MUA flexion angle between patients who underwent early versus late MUA (104.7 versus 104.1 degrees, p = 0.819). However, patients who underwent early MUA had poorer pre-MUA flexion (72.3 versus 79.6 degrees, p = 0.012), and subsequently had a greater overall gain in flexion compared to patients who underwent late MUA (mean gain 33.1 versus 24.3 degrees, p<0.001). Younger age was the only patient risk factor for MUA. A greater overall gain in flexion was achieved in patients who underwent early MUA within 3 months

Aim. The diagnosis of periprosthetic joint infection (PJI) remains a clinical dilemma, since presentations of PJI usually greatly overlap with aseptic failure (AF). The aim of this study is to evaluate the values of plasma fibrinogen, individually or in combination with CRP, ESR and WBC, for distinguishing PJI from AF. Method. We retrospectively enrolled 357 cases who underwent revision hip or knee arthroplasties in the Third Affiliated Hospital of Southern Medical University, Sun Yat-sen Memorial Hospital and the First Affiliated Hospital of Sun Yat-sen University from January 2013 to December 2021, including 197 AF, 116 PJI and 44 reimplantation. The diagnostic capacity of preoperative fibrinogen, CRP, ESR and WBC as well as their combinations for differentiating PJI from AF were assessed by ROC curves. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were calculated according to the optimal cutoff value based on the Youden index. All biomarkers were further investigated for their potential ability to predict optimal timing of reimplantation as well as their diagnostic capacity in the subgroups of the knee and hip PJI. Furthermore, the correlations among fibrinogen, CRP and ESR in the patients with PJI and AF were analyzed to further evaluate the potential capacity of fibrinogen in the diagnosis of PJI. Results. The levels of fibrinogen, CRP, ESR and WBC were significantly higher in PJI group than in AF group. ROC analyses showed that the AUCs of fibrinogen, CRP, ESR and WBC were 0.879, 0.903, 0.879 and 0.685, respectively. The optimal threshold of fibrinogen is 4.04 g/L (74.1% sensitivity, 85.6% specificity, 76.1% PPV, 85.0% NPV and 81.8% accuracy). Combining fibrinogen with CRP and/or ESR (AUC: 0.903∼0.914) yielded almost equivalent diagnostic efficiency compared with the combination of CRP and ESR (AUC: 0.910). Besides, fibrinogen yielded AUCs of 0.869 (cutoff: 3.44 g/L) and 0.887 (cutoff: 4.12 g/L) in the hip and knee subgroups, with higher specificity and PPV of 93.1% and 96.1% in the knee PJI. Intriguingly, as for the cases with CRP < 10mg/L and ESR ≧ 30 mm/h, the specificity and NPV of fibrinogen for diagnosing PJI were 92.2% and 83.9%. Conclusions. Plasma fibrinogen is considered as a potential first-line screening marker for PJI detection and timing of reimplantation. As for the patients with an increased ESR but normal CRP, a low fibrinogen level (below 4.04 g/L) is more likely to rule out PJI

Aim. Tourniquet is widely used in extremity surgery. In order to prevent surgical site infection, correct timing of antimicrobial prophylaxis and tourniquet inflation is important. We aimed to evaluate the time for which the free drug concentration of cefuroxime is maintained above the minimal inhibitory concentration (T>MIC) in subcutaneous tissue and calcaneal cancellous bone during three clinically relevant tourniquet application scenarios. Method. Twenty-four female pigs were included. Microdialysis catheters were placed for sampling of cefuroxime concentrations bilaterally in calcaneal cancellous bone and subcutaneous tissue, and a tourniquet cuff was applied on a randomly picked leg of each pig. Subsequently, the pigs were randomized into three groups to receive 1.5 g of cefuroxime by intravenous injection 15 min prior to tourniquet inflation (Group A), 45 min prior to tourniquet inflation (Group B), and at the tourniquet release (Group C). The tourniquet duration was 90 min in all groups. Dialysates and venous blood samples were collected eight-hours postcefuroxime administration. Results. Cefuroxime concentrations were maintained above the clinical breakpoint MIC for Staphylococcus aureus (4 µg/mL) in calcaneal cancellous bone and subcutaneous tissue throughout the 90 min tourniquet duration in Group A and B. Cefuroxime administration at tourniquet release (Group C) resulted in concentrations above 4 µg/mL for a minimum of 3.5 hours in the tissues on the tourniquet side. There were no significant differences in the T>MIC (4 µg/mL) in subcutaneous tissue or calcaneal cancellous bone between the three groups. However, Group A tended toward shorter T>MIC in tourniquet calcaneal cancellous bone compared to Group C (p=0.08). Conclusions. Administration of cefuroxime (1.5 g) in the 15–45 min window prior to tourniquet inflation resulted in sufficient calcaneal cancellous bone and subcutaneous tissue concentrations throughout the 90 min tourniquet application. If the target is to maintain postoperative cefuroxime concentrations above relevant MIC values, our results suggest that a second dose of cefuroxime should be administered at tourniquet release

Aim. The aim of this study is to evaluate if the gentamycin elution from bone cement is influenced by the timing of application of the antibiotic powder. Method. This was an experimental in vitro study that compared the elution properties of different formulation of gentamycin from a commercially available hip, knee and shoulder cement spacers. Four different experimental models were prepared. Five different spacers were prepared for each experimental mode and for each joint. We compared four different formulation of cement spacers: spacer #1, in which the spacer was prepared with a premixed bone-cement antibiotic mixture; spacer #2, in which the spacer was prepared by adding antibiotic powder to the bone cement at the time of spacer preparation; spacer #3, in which the spacer was prepared as spacer #2 but was stored for two months before starting the experiment; spacer #4, in addition to the gentamycin, other two antibiotics (tobramycin and vancomycin) were added to the bone cement. Gentamycin concentration was documented at seven intervals of time: T0 = 0h, T1 = 1h, T2 = 24h, T3 = 1W, T4 = 2W, T5 = 1M, T6 = 3M and T7 = 6M. The gentamycin elution at each interval of time was evaluated by using a T-student test. Results. Spacer #2, in which the gentamycin powder was added to the bone cement at the time of spacer preparation showed the higher gentamycin elution at each interval of time observed. In addition, Spacer #1, in which gentamycin powder was premixed with the bone cement showed a higher gentamycin elution when compared with spacer #3, in which the spacers were stored for two months to simulate the preformed spacers. Lastly, the addition of different antibiotic to the bone cement increases the gentamycin elution from the spacers (as demonstrated by spacer #4 model). Conclusions. a higher gentamycin elution was observed if spacer was prepared at the time of surgery when compared with preformed spacer. Lastly, our study confirmed the synergistic effect of adding one or more antibiotics with the aims to increase gentamycin elution

Two-stage treatment of chronically infected TKA is the most common form of management in North America and most parts of the world. One-stage management has pros and cons which will not be discussed in this lecture. There is great variation of techniques and timing and little data to definitively support one technique or timing approach vs. another. Most methods are based on empirical success and logic. At the time of surgery, the first step is removal of infected implants. All metallic implants and cement should be removed. The most common places to leave cement behind inadvertently include patellar lug holes, femoral lug holes, and the anterior proximal tibia behind the tibial tubercle. Formal synovectomy should be performed. The next step is typically antibiotic-impregnated spacer placement. There are pros and cons of dynamic and static spacers with no clear evidence of superiority of one vs. another. Dynamic spacers work satisfactorily with mild to moderate bone loss, but more severe bone loss is usually better treated with static spacers and a cast. Most antibiotic spacers are made of methyl methacrylate cement with addition of high-dose antibiotics. In most cases, doses of 4–8 gm of antibiotics per pack of cement are preferred. The type of dosing depends on the specific antibiotic and the type of cement used. The most common antibiotics used are vancomycin and gentamycin. When the femoral canals have been instrumented, antibiotic-impregnated cement wands are usually placed in the medullary canal, as the medullary canals have been shown to have high risk of residual bacteria being present. The resection interval may vary and there is no clear evidence of a “best” resection interval. Practically speaking, most surgeons use a resection period of 8–16 weeks depending on the type of spacer utilised. During the resection interval, serum markers (ESR and CRP) are followed periodically. One anticipates a decline or normalization of these parameters prior to second stage reimplantation procedure. There has not been a demonstrated advantage to reaspiration of the knee before reimplantation in most circumstances. At the time of reimplantation, the spacers are removed and the knee is redebrided. The key at the time of reimplantation is to obtain good implant fixation but to also balance this with the potential for manageable extraction of the implants at some later date. Good implant fixation is important because failure rates due to mechanical failure are approximately equal to those of failure due to reinfection by 10 years. It is important to remember that reinfection risk is at least 10% by ten years, and therefore extractability of implants is also important. Post-operative management typically includes IV antibiotics, followed by oral antibiotics until final intra-operative cultures are available. The results of two-stage reimplantation are reported in many series. Most show approximately 85–95% rate of successful eradication of infection in the first five years. Reinfections, often with different organisms, may occur even late after reimplantation. By ten years after surgery survival free of mechanical failure and infection in most series drops to 80% or less due to recurrent infections and mechanical failures

Background:. Cervical spine injured patients often require prolonged ventilatory support due to intercostal paralysis and recurrent chest infections. This may necessitate tracheotomy. Concern exists around increased complications when anterior cervical spine surgery and tracheotomies are performed. Objective:. The primary aim of this study was to evaluate the effect of tracheostomy in anterior cervical surgery patients in term of complications. In addition, the aetiology of trauma and incidence of anterior surgery and ventilation in this patient group was assessed. Methods:. Patients undergoing anterior cervical surgery and requiring ventilation were identified from the unit's prospectively maintained database. These patients were further sub-divided into whether they had a tracheotomy or not. The aetiology of injury and incidence of complications were noted both from the database and a case note review. Results:. Of the 1829 admissions over an 8.5 year period, 444 underwent anterior cervical surgery. Of these 112 required ventilation, and 72 underwent tracheotomy. Motor vehicle accidents, followed by falls, were the most frequent cause of injury. There was a bimodal incidence of tracheostomy insertion; on the day of spine surgery and 6–8 days later. There was no difference in the general complication rate between the two groups. With regards to specific complications attributable to the surgical approach / tracheotomy, there was again no statistically significant difference. The timing of the tracheotomy equally had no effect on complication rate. Although the complications occurred mostly in the formal insertion group as opposed to percutaneous insertion technique, this was most likely due to selection bias. Conclusion:. Anterior cervical surgery and subsequent tracheostomy are safe despite the intuitive concerns. Timing does not affect the incidence of complications and there is no reason to delay the insertion of the tracheotomy. Ventilation in general is associated with increased complications rather the tracheotomy tube

Aim. Debridement Antibiotics and Implant Retention(DAIR) is a procedure to treat a periprosthetic joint infection(PJI) after Total Hip Arthroplasty(THA) or Total Knee Arthroplasty(TKA). The timing between the primary procedure and the DAIR is likely a determinant for its successful outcome. There are few retrospective studies correlating timing of a DAIR with success (1,2). However, the optimal timing of a DAIR and the chance of success still remains unclear. We aimed to assess the risk of re-revision within one year after a DAIR procedure and to evaluate the timing of the DAIR in primary THA and TKA. An estimation of the chance of a successful DAIR will help clinicians and patients in their decision-making process in case of an acute postoperative PJI. Method. We used data from the Dutch Arthroplasty Register(LROI) and selected all primary THA and TKA in the period 2007–2016 who underwent a DAIR within 12 weeks after primary procedure. A DAIR was defined as a revision for infection in which only modular parts were exchanged. A DAIR was successful if not followed by a re-revision within 1 year after DAIR. The analyses were separated for THA and TKA procedures. Results. 207 DAIRs were performed <4 weeks after THA of which 41(20%) received a re-revision within 1 year; 87 DAIRs were performed between 4–8 weeks of which 15(17%) were re-revised and 11 DAIRs were performed >8 weeks and 2(18%) received a re-revision. 126 DAIRs were performed <4 weeks after TKA of which 27(21%) received a re-revision within 1 year; 68 DAIRs were performed between 4–8 weeks of which 14(21%) were re-revised and 15 DAIRs were performed >8 weeks and 3(20%) received a re-revision. Conclusions. There was no difference in 1-year re-revision rate after a DAIR procedure by timing of DAIR procedure for total hip and knee arthroplasty based on Dutch registry data

Aims. To determine whether a delay of greater than 6 hrs from injury to initial surgical debridement and the timing of antibiotic administration affect infection rates in open long-bone fractures in a typical district general hospital in the UK. Methods. In a prospective study, 248 consecutive open long-bone fractures (248 patients) were recruited over a 10-year period between 1996 and 2005. The data were collected in weekly audit meetings. Patients were followed until clinical or radiological union occurred or until a secondary procedure for non-union or infection was performed. The timing of the injury, initial surgical debridement, timing of antibiotic administration, and definitive procedures were all recorded. We also recorded the bone involved and the Gustillo and Anderson (GA) score. Patients who died within 3 months from the injury or who were transferred for definitive treatment were excluded. Results. Surgical debridement was performed before 6 hrs from injury in 62% of cases and after 6 hrs in 38% of cases. Infection rates were 7.8% and 9.6% respectively. The difference between the two groups was found to be not statistically significant (p=0.6438). This study has a 97% chance of demonstrating a difference of 20% (beta=0.2). The timing of administration of antibiotics was not found to be significantly related to the rate of infection; however, the GA grade of the injury had a strong correlation with subsequent infection. Conclusion. There was no significant rise in infection in patients receiving initial debridement after 6 hrs from the injury in comparison to patients who had this debridement within the 6-hour period. Whilst surgical debridement should be performed in the acute setting, we suggest that adherence to a 6-hour window is not imperative. Furthermore, the timing of antibiotic administration during the acute phase had little effect on infection rates

In order to define the optimum timing of surgery for a hip fracture, we undertook a systematic review of all previously published studies on this topic. Data from the retrieved studies were extracted by two independent reviews and the methodology of each study assessed. In total, 43 studies involving 265,137 patients were identified. Outcomes considered were mortality, post-operative complications, length of hospital stay and return of patients back home. There were no randomised trials on this topic. Six studies of 8535 patients have the most appropriate methodology, which was prospective collection of data with adjustment for confounding variables. These studies found no effect on mortality for any delays in surgery. One of these studies found fewer complications for those operated on early but this was not found in the other study to report on these outcomes. Two of these studies reported on hospital stay, which was reduced for those operated on early. Six studies of 229,418 patients were retrospective reviews of patient administration databases with an attempt at adjusting for confounding factors. They reported a reduced mortality, hospital stay and complications for those operated on early. Thirty-one other studies of variable methodology reported similar findings of reduced complications with early surgery, apart from one study of 399 patients which reported an increased mortality and morbidity for those operated on within 24 hours of admission. In conclusion those studies with more careful methodology were less likely to report a beneficial effect of early surgery, particularly in relation to mortality. But early surgery (within 48 hours of admission) does seem to reduce complications such as pressure sores and reduces hospital stay

We reviewed 87 patients who underwent revision anterior cruciate ligament (ACL) reconstruction. The incidence of meniscal tears and degenerative change was assessed and related to the timing from primary ACL graft failure to revision ACL reconstruction. Patients were divided into either an early group (revision surgery within 6 months of graft failure) or a delayed group. Degenerative change was scored using the French Society of Arthroscopy system. There was a significantly higher incidence of articular cartilage degeneration in the delayed group compared to the early group (53.2% vs 24%, p < 0.01, Mann- Whitney U test). No patients in the early group had advanced degenerative change (SFA grades 3 or 4), compared with 12.9% of patients in the delayed group. There was no significant difference in the incidence of meniscal tears between the two groups. In conclusion, the findings of the study support the view that patients with a failed ACL reconstruction and symptomatic instability should have an early revision reconstruction procedure carried out to minimise the risk of articular degenerative change

Forefoot surgery causes postoperative pain which requires strong painkillers. Regional blocks are now increasingly used in order to control postoperative pain especially in the first twenty four hours when the pain is at its worst. We conducted a study to see whether timing of ankle block i.e. before or after application of tourniquet shows any difference in efficacy in postoperative analgesia in first twenty four hours. A prospective study was conducted between September and March 2011 involving 50 patients. Group A had ankle block after and Group B had block before application of tourniquet. Both group had twenty five patients each. Patients were given assessment forms to chart their pain on Visual Analogue Scale (VAS) at 4hrs and twenty four hours after surgery. Both groups demonstrated good postoperative pain control. Average pain score at four and twenty fours after surgery was 2.5 and 5 in Group A and 3.5 and 6.1 in Group B respectively. Pain control, both at four and twenty four hours surgery was better in Group A but this was not statistically significant. Ankle block should be routinely used in forefoot surgery to control postoperative pain. Ankle block before or after the application of tourniquet had comparable pain relief with no statistical difference

Aim

Local antibiotics released through a carrier is a commonly used technique to prevent infection in orthopaedic procedures. An interesting carrier in aseptic bone reconstructive surgery are bone chips impregnated with AB solution. Systemically administered Cefazolin (CFZ) is used for surgical site infection prophylaxis however in vitro study showed that fresh frozen and processed bone chips impregnated with CFZ solution completely release the CFZ within a few hours. On the other hand irradiated freeze-dried bone chips, treated with supercritical CO2 (scCO2) have been shown to be an efficient carrier for the antibiotics vancomycine or tobramycine.

With this pilot study we wanted to investigate if CFZ solution impregnation of bone chips treated with scCO2 shows a more favorable release pattern of CFZ.

The infected TKA is one of the most challenging complications of knee surgery, but spacers can make them easier to treat. An articulating spacer allows weight bearing and range of motion of the knee during rehabilitation. This spacer is made using antibiotic-impregnated bone cement applied to the tibial and femoral implants. For our purpose, 4.8g powdered tobramycin is mixed with 2gm vancomycin and one batch of antibiotic. Cement is applied early to the components, but applied late to the femur, tibia, and patella to allow molding to the defects and bone without solid adherence to bone. Patients have tailored intravenous antibiotic therapy for 6 weeks for treatment of various gram-positive and gram-negative organisms. At 10–12 weeks patients are revised to a cemented revision total knee arthroplasty using standard cementing techniques. From our experience, range of motion before reimplantation was 5 – 90 degrees. Follow-up averaged 73 months for fifty patients with 90% good to excellent results; 10% had a recurrence of infections. Use of an articulating spacer achieves soft tissue compliance, allows for ease of re-operation, reduced postoperative pain, improved function, and eradicates infection equal to standards reported in the literature.

Deep peri-prosthetic infection after partial or total knee arthroplasty is a disconcerting problem for patient and surgeon alike. The diagnosis of infection is sometimes obvious but frequently requires that the surgeon maintain a substantial index of suspicion for infection as the cause of pain or poor outcome after any joint arthroplasty. While surgical debridement with component retention is appropriate in a subgroup of patients with an acute peri-prosthetic infection, most delayed and chronic infections are best treated with component resection. With carefully selected patients and very aggressive debridement protocols some success has been demonstrated in Europe with single-stage exchange for infection. Most surgeons in North America, however, are unfamiliar with the very aggressive debridement techniques employed at European centers that promote single stage replant; and few surgeons in North America are currently comfortable in cementing a hinged total knee replacement in place for the typical infected TKA nor do they have the patience to re-prep and drape with an entirely new OR setup after debridement and prior to the insertion of the new implant − 2 steps that are often mentioned as important to the success of single stage exchange.

The pre-eminent role of two-stage exchange as the definitive treatment was established over 30 years ago. Two-stage exchange remains the gold-standard in treatment with an established track record from multiple centers and with multiple different types of infecting organisms. Some of the historical problems with two-stage exchange, such as limited mobility during the interval stage, have been mitigated with the development of effective articulating spacer techniques. Further, the emergence of drug resistant bacteria and the possibility of fungal infection make two-stage exchange the best choice for the majority of patients with deep periprosthetic joint infection in 2017.

Aim

The reconstruction of bone critical size defects of the tibia is one of the most complex therapeutic challenges in the orthopedic field. This study aims to describe and evaluate our three-staged surgical protocol of reconstruction of infected defects of the tibia emphasizing in limb salvage rate, resolution of infection, functional outcome and patient satisfaction.

There is great debate around how to treat patients with periprosthetic joint infections and there are different techniques utilised throughout the world with large regional differences. In the situation where implants are well fixed there is a potential advantage to retain ingrown implants in which removal would result in severe bone damage. However, there are multiple variables on both the patient side and the surgeon side which can influence the likelihood of success with this approach. In some patients, staged revision of large and well-fixed components will result in bone damage and compromised function, but the two-stage techniques may have great success at long term infection free survivorship. The literature suggests that selective implant retention and joint débridement may be an alternative for those patients who have complex well-fixed components, are not immunocompromised, have not developed sinus formation, and who have less virulent organisms on aspiration. Implant retention techniques should be approached with caution when patients have chronic illness such as diabetes or rheumatoid disease, use immunosuppressive medications, have a negative aspirate for microorganisms, or show any signs of loosening on radiographs or during intra-operative assessment. Like many aspects of patient care, proper patient selection and meticulous surgical techniques are important components to increasing success in these difficult clinical scenarios. This talk will focus on the data currently available in the literature to help participants gain a better understanding of how to individualise treatments for patients with periprosthetic infections.

Two stage exchange treatment of the infected TKA involves two separate surgical procedures separated by an interval of several weeks of pathogen specific antibiotic therapy.

The first stage involves removal of all of the infected arthroplasty components and any cement or foreign material, followed by aggressive debridement of nonviable bone and soft tissues. This is followed by placement of an antibiotic-laden spacer which may be either static (molded solid PMMA block) or mobile (shaped blocks or implants that allow knee motion). With both static and mobile spacers high local doses of antibiotic are delivered from the cement in addition to systemic antibiotic therapy usually employing an IV for around 6 weeks post debridement. The choice between static and mobile spacers is dictated by surgeon preference, soft tissue status (i.e. need for adjunctive muscle flaps), and by the severity of bone loss present with static spacers more likely to be used for more major soft tissue or bone defect cases. Mobile spacers have the advantage of allowing interval motion of the knee which may improve final range of motion. Static spacers usually require adjunctive brace or cast immobilization to prevent migration and bone damage.

The second stage is performed at around 6 to 8 weeks after completion of systemic antibiotic therapy and preferably after normalization (or improvement) in laboratory indicators such as ESR and CRP. Routine repeat aspiration of all knees before reimplantation is not usual, but selective aspiration for culture may be helpful if concern exists that infection may still be present due to systemic signs, wound appearance or abnormal laboratory parameters. The second stage procedure involves removal of the antibiotic-laden spacer, repeat complete debridement of the knee, and insertion of revision knee components. Frequently adjunctive stems, blocks, cones or sleeves are needed to achieve adequate implant fixation due to associated bone loss. Careful attention to soft tissue balancing is required at the time of reimplantation in order to optimise motion and function while also avoiding laxity or maltracking.

Two stage exchange remains the gold standard in North America for the management of infected TKA. While this method is used by some surgeons for all chronically infected TKA patients, it is employed even by most one stage exchange devotees when the infecting organism is unknown, infection involves a highly resistant or difficult to manage pathogen (i.e. fungal), is associated with a sinus track or marginal soft tissues, or in many cases of immunocompromised patients or those with multiple comorbidities.

Two-stage exchange has been the gold standard in North America for the treatment of infected knee replacements. The choice of static versus articulated spacers has been debated for a number of years.

At our institution our choice of spacer for 2-stage exchanges is an articulated spacer. This allows motion between stages which facilitates recovery, and makes the second stage technically easier. In a study from our institution we followed 115 infected TKAs treated with the PROSTALAC articulated spacer for 5–9 years. Success for eradication of infection was 88%. With a repeat two-stage, overall infection control was 98%. In addition, we compared functional outcomes to a group of aseptic knee revisions and found no difference in functional outcomes with standard quality of life outcome scores.

While the articulated spacers were our treatment of choice in 2-stage exchange, around 2012 the company that manufactured the PROSTALAC knee components ceased to manufacture them, based on the work of 2 previous studies (Hofmann, Lee). At our institution, we continued to use articulated spacers. However, this was now the so-called Hofmann technique with a new standard femoral component with an all-polyethylene tibia. The only difference from a standard knee revision was no stems and the utilization of high dose antibiotics.

Around the same time as we instituted the change in articulated spacers, results out of Europe were showing promising results with one-stage exchange. In September 2015, our technique was modified to now include an all-polyethylene tibia with a keel. To date we have no results but it is our hope that a high percent of these will achieve stable fixation and will then have a one-stage exchange.

The question of whether to reconstruct an ACL-deficient knee as early as possible following injury or to delay surgery remains unanswered. Early reconstruction potentially reduces the risk of secondary damage. However, there is also concern regarding the risk of arthrofibrosis if surgery is undertaken too soon. The aim of this study was to investigate whether injury-to-surgery delay determines ACL-reconstruction outcomes at up to 2years post-operatively.

A retrospective analysis of prospectively collected data from 211 knees with isolated primary ACL ruptures was performed. Patients were examined preoperatively, at 6months, 1 year, and 2 years post-operatively using International Knee Documentation Committee (IKDC) and Lysholm scores. Side to side differences in knee laxity were also measured with a KT1000 arthrometer. Spearman's rho correlations were used to associate injury-to-surgery delay with outcome scores.

Outcomes scores significantly increased for both IKDC (p<0.05) and Lysholm (p<0.05) questionnaires. Significant positive correlations (p<0.05) were also found between injury-to-surgery delay and IKDC and Lysholm subjective scores. Strongest correlation coefficients were noted at the 2yr follow-up for both IKDC and Lysholm scores (r = 0.79 and 0.8 respectively). Side-to-side laxity measures also showed significant positive correlations with injury-to-surgery delay at 1 year (r = 0.17) and 2 year (r = 0.41) follow ups. The positive correlation suggests that delayed surgery is positively related to subjective outcomes, as well as objective measures of knee laxity.

However, this relationship also suggests that other factors such as the patient's functional status at time of surgery may play a role in their post-operative function. For example, those who can compensate for the ruptured ligament may function well following delayed surgery. These findings highlight the need for more detailed investigation of the interaction between functional status, injury-to-surgery delay and post-operative recovery.

Introduction. Evidence suggests that intra-operative spinal cord monitoring is sensitive and specific for detecting potential neurological injury. However, little is known about surgeons' responses to trace changes and the resultant neurological outcome. Objective. To examine the role of intra-operative somatosensory evoked potential (SSEP) monitoring in the prevention of neurological injury, specifically sensitivity and specificity, and whether the abnormalities were reversible. Methods. 2953 consecutive complex spine operations (male 36% female 64%, median age 25yrs) prospectively performed using spinal cord monitoring at a single institution (2005–2009). All traces and neurophysiological events were prospectively recorded by the neurophysiology technician. All patients with a significant neurophysiology event were examined clinically by a neurologist, separate from the spinal surgery team. Significant trace abnormality was defined as a decrease in signal amplitude of 50% or a 10% increase in latency. Timing of trace abnormality, surgeon's response and prospective neurological outcome were recorded. Sensitivity, specificity, positive/negative predictive value were calculated. A Chi-squared test was performed to assess the impact of intervention on neurological outcome (p < 0.05). Results. 2953 operations involving SSEP monitoring were performed and 106 recorded a significant trace abnormality. This most often occurred during instrumentation and the most common reaction was adjustment of metalwork. SSEP monitoring had a sensitivity of 100%, specificity 97.3%, PPV 24%, NPV 100%. There were 79 false positives and no false negatives in this series. Chi-squared test was not significant (p=0.18) suggesting that intervention might not affect neurological outcome in this cohort. Conclusions. Triggering events are uncommon and the development of a persistent neurological deficit is rare with an incidence of 0.85% in this series of 2953 operations. In the majority of cases detection of a monitoring abnormality prompts a corrective reaction by the surgeon. Of those with an abnormal trace 76% were neurologically normal at follow up