Midflexion instability in primary total knee replacement: a review.

INTRODUCTION: Midflexion instability in primary total knee replacement (TKR) is an evolving concept. Successful treatment of instability requires an understanding of the different types of instability. METHODS: A literature review was performed to identify information pertinent to midflexion instability in primary total knee replacement, utilising PRISMA guidelines. Databases searched included Embase, Medline, All of the Cochrane Library, PubMed and cross references. RESULTS: Three factors, i.e., elevated joint line, multiradii femoral component and medial collateral ligament (MCL) laxity, were identified to influence midflexion instability. Literature suggested mediolateral instability at 30-60° of flexion as diagnostic of midflexion instability. Literature search also revealed paucity in clinical studies analysing midflexion instability. Most of the evidence was obtained from cadaveric studies for elevated joint line and MCL laxity. Clinical studies on multiradii femoral component were limited by their small study size and early followup period. CONCLUSION: Elevated joint line, multiradii femoral component and MCL laxity have been suggested to cause midflexion laxity in primary TKR. Due to limitations in available evidence, this review was unable to raise the strength of overall evidence. Future well-designed clinical studies are essential to make definitive conclusions. This review serves as a baseline for future researchers and creates awareness for routine assessment of midflexion instability in primary total knee replacement.

Total knee replacement following high tibial osteotomy versus total knee replacement without high tibial osteotomy: a systematic review and meta analysis.

INTRODUCTION: Currently, there is no consensus as to whether total knee replacement(TKR) following high tibial osteotomy(HTO) provides similar postoperative outcomes as compared to TKR without previous HTO. Previous studies have provided limited evidence to small sample sizes and methodological inappropriateness. METHODS: A systematic search process was conducted utilising PRISMA guidelines. Electronic, peer reviewed and published literatures were searched. Databases searched include Embase, Medline, Cochrane Library, PubMed and cross references. Methodological appropriateness was assessed with Papadokastakis system and Critical Appraisal Skills questionnaire. Data were analysed for both clinical and statistical homogeneity. Meta analytic pooling was subsequently performed. RESULTS: 11 studies including 2170 TKR procedures were analysed for systematic review. The study (TKR following previous HTO) and control (TKR without previous HTO) groups were adequately matched for age, sex ratio and follow-up. Meta analysis of six studies utilising KSS system and four studies utilising HSS system showed no significant (p > 0.05) difference between the two groups. Complications also showed no significant difference between the two groups. At an average follow-up of 7.2 years, with revision arthroplasty for any cause as the endpoint, survivorship for the study and control groups was 95 and 97 %, respectively. For revision arthroplasty with aseptic loosening as the end point, the survivorship was 98 % for both groups. CONCLUSION: Systematic review and meta analysis suggested that TKR following HTO provides similar outcomes as compared to TKR without previous HTO. Therefore, a previous HTO does not negatively influence a future TKR, though the conversion process of HTO to TKR is technically challenging. Systematic review also identified paucity in prospective and long term studies.

Interobserver and intraobserver variations in tibial pilon fracture classification systems.

BACKGROUND: Tibial pilon injuries are a complex group of fractures, whose classification and radiological assessment has been under constant reform. Till date, there is no universally accepted classification system. OBJECTIVE: To determine the interobserver agreement and intraobserver reproducibility of Ruedi and Allgower, AO, and Topliss et al. classification systems for tibial pilon fractures, with CT scans. METHOD: Forty-seven CT scans of tibial pilon fractures were evaluated independently by 5 orthopaedic surgeons. Fractures were classified according to Ruedi and Allgower, AO and Topliss et al. types. Assessment was done on two occasions, eight weeks apart. RESULTS: The interobserver reliability and intraobserver reproducibility for Ruedi and Allgower, AO and Topliss et al. classifications showed only moderate agreement. The interobserver agreement was dependent on the familiarity and specificity of the classification system. CONCLUSION: Currently used classification systems for tibial pilon fracture have moderate interobserver and intraobserver agreements, even with the help of CT scans. Therefore Tibial pilon fracture classification still remains largely undetermined.

Direct exchange endoprosthetic reconstruction with tumour prosthesis for periprosthetic knee infection associated with segmental bone defects.

Revision knee arthroplasty for infection poses a treatment challenge. The presence of massive osteolysis limits the treatment options in this cohort. Controversy exists in the management of these patients. Direct exchange arthroplasty has provided good results in the presence of infection, but whether this is appropriate in the presence of massive bone defects associated with the infection is undetermined. We present our experience in revision knee arthroplasty for infection associated with massive bone defects. The aim of the study is to present the preliminary results of a direct exchange endoprosthetic reconstruction with tumour prosthesis for periprosthetic infection associated with segmental bone defects. This is a retrospective study of prospectively collected data, involving six patients with periprosthetic infection and massive bone defects treated by direct exchange tumour prostheses between 2003 and 2007 (four distal femoral replacements and two total femoral replacements). The mean age and follow-up were 74.2 (+/-5.2) years and 32.5 (+/-8.2) months respectively. Each patient had an infected revised knee arthroplasty at the time of referral to our institution. Staphylococcus aureus was the most common causal organism. The mean duration of antibiotics was 6 weeks intravenous therapy followed by 3.5 months oral. The recurrences of infection, pain or immobility were outcome criteria considered failures. Our success rate was 80%. Salvage of infected revised knee arthroplasty by direct exchange endoprosthetic reconstruction has provided an effective means of pain relief, joint stability and improved mobility in our cohort. It reduces morbidity through earlier mobilisation and avoids a second major operation.

Early results of a new highly porous modular acetabular cup in revision arthroplasty.

BACKGROUND: The 'Tritanium' (Stryker, New Jersey, USA) highly porous acetabular cup is a new implant used in revision hip arthroplasty. AIM: To determine the early results of this device. METHODS: A prospective study of 43 acetabular component revisions performed using the implant between March 2007 and February 2008 was undertaken. All procedures were performed at a single centre with standard approach and follow up. RESULTS: The mean age of patients at surgery was 66 years. Mean follow up was 18.2 months. AAOS classification revealed 17% Type 1, 49% Type 2, 24% Type 3 and 5% Type 4 defects at surgery. 5% had no bone defect. Bone graft was used to in 73% of patients. Mean Harris Hip Score improved from 68 pre-operatively to 86 at the last follow-up. Cup integration was seen in 95% of patients by 6 weeks. One patient with pelvic discontinuity had symptomatic aseptic loosening which was revised. CONCLUSION: The 'Tritanium'acetabular cup has been successful in achieving rapid osseointegration with few complications. The management of pelvic discontinuity continues to be a challenge.

Early catastrophic failure of Birmingham acetabular dysplasia cup in revision arthroplasty: a case report.

INTRODUCTION: Revision acetabulum arthroplasty is one of the common procedures, which has been on the rise recently. Many implants are available in the market with variable results. Aseptic loosening is the most common indication for revision acetabulum arthroplasty. Birmingham dysplasia cup has been used occasionally in these complex procedures. We know that these implants have provided good results in resurfacing dysplastic hips with bone loss. Literature review failed to answer whether these implants were as effective in revision acetabulum arthroplasty. CASE PRESENTATION: We herby, present a case of revision acetabulum arthroplasty performed with Birmingham dysplasia acetabular cup, which unfortunately failed within a period of eight months. Surgical technique appeared to be adequate. On further analysis, significant differences were identified between dysplastic hips with bone loss and revision hips with bone loss. CONCLUSION: Therefore results obtained with dysplasia cups in resurfacing dysplastic hips does not seem to be applicable to revision hip arthroplasty. Hence these cups should be restricted to primary arthroplasty.

Unique relationship between osteophyte and femoral-tibia component size mismatch in determining polyethylene wear in primary total knee arthroplasty: a case report.

INTRODUCTION: Knee pain is a complex problem that can occur after total knee arthroplasty. One cause of knee pain may be due to a retained osteophyte, but it is not clear if the retained osteophyte is sufficient explanation of the pain, as not all patients with retained osteophytes are symptomatic. In fact, the literature shows that excised osteophytes can also recur over a period of time, without any symptoms. Therefore a retained osteophyte alone is probably not sufficient to cause symptoms. CASE PRESENTATION: We present a case of intermittent medial knee pain occurring post-primary total knee arthroplasty, in a patient who underwent several investigations over a period of 5 years. Radiographs showed an osteophyte in the postero-medial femur along with slight tibial component overhang which was normal for that knee implant design. The symptoms eventually settled with excision of only the osteophyte, without altering the tibial component. CONCLUSION: A retained osteophyte alone, or tibial component overhang alone, did not seem to cause significant symptoms in our patient whose symptoms completely settled with excision of the osteophyte alone, without changing the tibial component. Therefore, it seems that the combination of retained osteophyte and tibial component overhang (tibia-femoral component size mismatch) are detrimental and therefore best avoided. This report also emphasises the importance of meticulous osteophyte excision and avoiding tibial component overhang during knee arthroplasty.

Can 'sniff nasal inspiratory pressure' determine severity of scoliosis in paediatric population?

INTRODUCTION: Sniff nasal inspiratory pressure (SNIP) has become a valuable tool in assessing respiratory muscle weakness. Its role in the scoliosis population is still being defined. AIM: To assess significance of SNIP value in paediatric patients with scoliosis. METHODS: Eighty-nine paediatric patients were investigated with SNIP at the time of preoperative assessment for scoliosis surgery from January 2000 to December 2006. Patients were divided into neuromuscular (24) and idiopathic (55). Other causes and revision were excluded (10). SNIP was evaluated with respect to curve pattern and curve degree. RESULTS: The mean SNIP value for the idiopathic and neuromuscular groups was 63 (+/-23) and 35 (+/-14) cmH(2)O, respectively. The mean Cobb angle for idiopathic and neuromuscular group was 58 (+/-18) and 67 (+/-16) degrees, respectively. Spearman's rank correlation coefficient showed no statistically significant correlation between SNIP value and curve degree. Chi-squared test showed a statistically significant association between SNIP and curve pattern (P = 0.006). DISCUSSION: SNIP is a valuable test when used in conjunction with vital capacity and overnight oxygen saturation, height, comorbidities in the neuromuscular population. It is a sensitive indicator of respiratory muscle weakness. Low SNIP values are found in neuromuscular scoliosis in general. It does not appear to reflect increasing curve severity.