Two-stage Partial Component Retention and Interim Cemented Liner for Infected Total Hip Arthroplasty: A Case Report.

Introduction: There is interest in partial exchange for infected total hip arthroplasty, as an alternative to complete removal of components in a traditional two-stage revision. Partial exchange avoids the difficulty of removing a well-fixed component and its associated bone loss. Case Report: We report a case of a 61-year-old male patient with an infected total hip arthroplasty, who underwent a two-stage partial exchange, with retention of the well-fixed femoral stem, and an interim cemented liner. He had excellent function and no infection recurrence at 4 years of follow-up. Conclusion: Two-stage partial exchange with interim cemented liner could be an effective option for infected total hip arthroplasty.

Does Barbed Suture Lower Cost and Improve Outcome in Total Knee Arthroplasty? A Randomized Controlled Trial.

BACKGROUND: Wound closure is key to prevent infection, facilitate immediate rehabilitation, and improve efficiency of total knee arthroplasty (TKA). Continuous knotless suturing with barbed suture can potentially save time and distribute tension more evenly. However, its role in TKA in terms of cost-effectiveness and wound complications is not clear. This study aims at comparing barbed and traditional sutures' wound closure time and cost in primary TKA. METHODS: One hundred nine knees were randomized into either barbed or traditional group. Synthetic absorbable sutures (Vicryl, Ethicon Inc) and bidirectional barbed sutures (Stratafix, Ethicon Inc) were used. Arthrotomy and subcutaneous wound closure time, wound complications, and rehabilitation parameters in terms of range of motion and Knee Society Score were compared. Patients were followed up to 3 months. RESULTS: Traditional sutures had significantly more positive leak tests (10 vs 2, P value <.05) and wound complications (11 vs 2, P value <.05). No differences in range of motion and Knee Society Score were noted. Arthrotomy and subcutaneous closure time were significantly shorter with barbed sutures (arthrotomy 325 seconds vs 491 seconds; subcutaneous 306 seconds vs 381 seconds, P value <.05). Concerning cost of suture material and operation time, barbed suture on average saved USD 48.7 per TKA in our local institute. CONCLUSION: Bidirectional barbed suture improves the cost-effectiveness of TKA through reducing wound closure time and wound complications.

Polyethylene Insert Exchange Is Crucial in Debridement for Acute Periprosthetic Infections following Total Knee Arthroplasty.

This study aims to report our experience of managing acute periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) with surgical debridement and prostheses retention. A review of patients in our prospective joint replacement register from 1998 to 2013 was performed. In this study, 34 patients with 35 TKAs were included; 25 were infections after primary TKA and 10 were after revision TKA. For primary TKA infections, after a mean follow-up of 53.8 ± 42.6 months, 11 were successfully treated, while 14 failed, including 10 required reoperations and 4 needed lifelong antibiotic suppression. The success rate of debridement was 44.0%. Statistical analyses showed no significant differences between the two groups on patients' age, time lag between symptoms onset and debridement, preoperative C-reactive protein, erythrocyte sedimentation rate, white blood cell count, hemoglobin, albumin, glucose, or synovial fluid total cell count. Patients' primary diagnoses or staphylococcal infections had no significant impact on the surgical outcomes either. Debridement with polyethylene insert exchange had significantly higher success rate than debridement alone, with all 13 cases without exchange failed. All 10 cases with infections after revision TKA had failed. We concluded that debridement with prostheses retention has a low success rate for acute PJI following primary TKA. The polyethylene insert should be exchanged during surgery. For acute infections after revision TKA, total revision should be contemplated.

Comparison between patient-specific instruments and conventional instruments and computer navigation in total knee arthroplasty: a randomized controlled trial.

PURPOSE: The current study investigated the accuracy in achieving proper lower limb alignment and individual component positions after total knee arthroplasty (TKA) with 3 different instrumentation techniques. It was hypothesized that patient-specific instruments (PSI) would achieve more accurate lower limb alignment and component positions compared to conventional instruments (CON). METHODS: Ninety knees in 81 patients were randomized in 1:1:1 ratio into CON, computer navigation (NAV) and PSI groups to receive TKA. The surgical routines were standardized. The lower limb mechanical axis and individual component positions were assessed on standard radiographs. Tourniquet time, operation time and patients' functional scores were documented. RESULTS: Conventional instruments and PSI were more likely to result in an excessively flexed femoral component (p = 0.001) compared to NAV. Number of outliers in postoperative lower limb alignment, and other components positions in the coronal and sagittal plane showed no statistically significant difference. The mean tourniquet time and operation time was significantly shorter in CON and PSI groups than NAV group (p < 0.001). Four early complications occurred in the PSI group (p = 0.015). At 3-month follow-up, there was no difference in terms of the knee range of motion and patients' function among the 3 groups. CONCLUSION: No significant radiological and clinical benefit could be demonstrated in using PSI over CON or NAV in TKA. Routine use of PSI is not recommended because of the extra cost and waiting time. LEVEL OF EVIDENCE: I.

Anterior dislocation after total hip replacement - effects of pelvic rotation and femoral head size.

We investigated the effects of pelvic rotation and femoral head diameter on the anterior stability of the hip joint after total hip replacement. Computer navigation and cadaveric bone were used to simulate the range of motion after total hip replacement. The hip was put at 0 degrees of flexion and it was gradually externally rotated until the hip dislocated. The degree of external rotation when the hip was dislocated was recorded. The test was repeated with the hip at +10, -10, -20, -30, -40 and -50 degrees of flexion. The acetabular component was positioned with abduction of 45 degrees and anteversion at 20 degrees. There was a significant difference amongst each group of pelvic rotation from 0 to -50 degrees in the degree of external rotation when the hip was dislocated. The degree became insignificant when pelvic rotation was increased from 0 to 10 degrees. From -10 to -50 degree of pelvic rotation, 36mm head had significant better stability compared with 32mm and 28mm femoral heads. The presence of significant pelvic sagittal malrotation can increase the risk of anterior dislocation. A larger femoral head is more stable than smaller heads. When pelvic sagittal malrotation is not present, there is no difference in stability between large and small femoral heads.

Notching of the femoral stem neck in metal-on-metal total hip replacement: a case report.

We report a case of impingement in a metal-on-metal total hip replacement causing both notching of the femoral stem neck and aseptic loosening of the acetabular component. The acetabular component was inserted in excessive anteversion. The femoral stem and acetabular components were retrieved. A larger femoral head was used, and an acetabular component was placed in a less anteverted position. Intra-operative testing through different ranges of movement is recommended to identify potential impingement.

The accuracy of sizing of the femoral component in total knee replacement.

PURPOSE: Femoral sizing in total knee replacement is important. Either undersizing or oversizing may result in deleterious effects to the clinical outcome after the surgery. There has been no study on the precision and accuracy of femoral sizing and the effect of measurement at different landmarks over the distal femur. This study assesses the intra-observer and inter-observer error of femoral sizing and identifies the effect of the placement site of the anterior referencing tool on femoral sizing. METHODS: Five investigators with different clinical experience measured the femoral size of 10 cadaveric specimens twice using three anterior referencing tool. The measurement of the femoral size was repeated at nine designated points on the anterior cortex of the cadaveric femora. RESULTS: Excellent intraobserver and interobserver agreements were obtained using the three anterior referencing tools. When the size on which the majority agreed was regarded as the actual size of the specimen, measurement at the nine designated points on the anterior cortex showed a deviation from the actual size from 6.2 to 46.2 %. Placing the femoral sizer stylus at the middle and 2 cm above the proximal margin of the anterior femoral condyle yielded the highest precision and accuracy. CONCLUSION: Regardless of the experience of the surgeons, measurement of the femoral size using the three anterior referencing tools is very accurate. Placing the stylus of the femoral sizer at the middle and 2 cm above the proximal margin of the anterior femoral condyle best reflects the actual size of the femur. LEVEL OF EVIDENCE: Experimental study.

Continuous femoral nerve block versus patient-controlled analgesia following total knee arthroplasty.

PURPOSE: To compare total knee arthroplasty (TKA) patients who received continuous femoral nerve block (FNB) with local anaesthetics through a catheter versus patient-controlled analgesia (PCA) with intravenous morphine. METHODS: 50 women and 10 men aged 51 to 84 years with matched characteristics underwent TKA and received either continuous FNB with local anaesthetics through a catheter (n=30) or PCA with intravenous morphine (n=30). None of the patients had had previous knee surgery. All operations were performed according to the standard protocol. Daily mean pain numerical rating scale at rest (NRS-R) and during movement (NRS-M), requirement of extra pain control, complications related to pain control, and overall patient satisfaction in both groups were compared. RESULTS: Both groups were similar in terms of pain NRS-R and NRS-M, overall satisfaction, and length of hospital stay. Within each group, pain NRS-M score was significantly higher than pain NRS-R score. In the FNB group, 3 patients had dislodgement of the femoral catheter on day 1 and switched to PCA with intravenous morphine. Two of them had fair satisfaction. Patients in the PCA group had significantly more side-effects (nausea, vomiting, dizziness, and pruritis); 2 of the 5 patients with nausea and vomiting had fair satisfaction. No patients had any surgical complication. CONCLUSION: Both FNC and PCA provide reliable pain control.

Review article: Treatments for bone loss in revision total knee arthroplasty.

Bone deficiency hinders implant alignment and stabilisation of the bone-implant interface in revision total knee arthroplasty (TKA). Treatments for bone defects include bone cement, bone cement with screw reinforcement, metal augments, impaction bone grafts, structural allografts, and tantalum, depending on the location and size of the defects. Small defects are usually treated with cement, cement plus screws, or impaction allograft bone. Large defects are repaired with structural allografts or metal augments. Recent developments involve the use of highly porous osteoconductive tantalum. We reviewed the pros and cons of each method for bone defect management in revision TKA.

Multimodal periarticular injection vs continuous femoral nerve block after total knee arthroplasty: a prospective, crossover, randomized clinical trial.

This study compares the efficacy of pain control using continuous femoral nerve block (FNB) and multimodal periarticular soft tissue injection. This is a randomized, crossover, clinical trial. Sixteen patients having bilateral osteoarthritis of the knee scheduled for staged total knee arthroplasty were randomized to receive either FNB (0.2% ropivacaine), via indwelling catheter for 72 hours, or multimodal periarticular soft tissue injection in the first stage. In the second stage, they received the opposite treatment. The primary outcome measure was morphine consumption by patient-controlled analgesia in the first 72 hours postoperatively. Cumulative morphine consumption as well as rest pain and motion pain in the first 72 hours was comparable between the 2 groups. The functional outcomes did not differ significantly. We conclude that multimodal periarticular soft tissue injection provides comparable analgesia to continuous FNB after total knee arthroplasty.

Review article: bone defect classifications in revision total knee arthroplasty.

There are several classification systems for bone defects in revision total knee arthroplasty. Each has its own drawbacks, and none satisfies all the clinical demands. Therefore, a new classification system and treatment guideline based on a combination of criteria (location, side, containment, and severity of the bone defect) is necessary.

A cadaveric study of posterior dislocation after total hip replacement-effects of head diameter and acetabular anteversion.

The size of the femoral head and acetabular anteversion are crucial for stability in total hip replacements. This study examined the effects of head diameter and acetabular anteversion on the posterior instability after total hip replacement in an in vivo setting. The acetabular shell was inserted at 0-20° of anteversion at five degree intervals. By using different head sizes (28 mm, 32 mm, 36 mm), the degrees of dislocation were recorded by computer navigation. The 36-mm group consistently showed better stability compared with the 32- and 28-mm groups, regardless of the degree of cup anteversion. Within each group of head size, the hip was significantly more stable when the cup anteversion increased from 0° to 10°. The difference became insignificant when it increased from 15° to 20°.

Revision total hip arthroplasty with femoral impaction bone grafting.

PURPOSE: To report the radiological and clinical results of revision total hip arthroplasty (THA) with femoral impaction bone grafting (IBG). METHODS: 4 men and 9 women (15 hips) aged 38 to 84 years underwent revision THA with femoral IBG using Elite plus stems for aseptic loosening or infection. RESULTS: The mean follow-up duration was 7.7 years. The Harris hip score improved from 61.7 to 83.7. There was no pain in 11 hips and slight pain in 4. The mean subsidence was 5.7 mm. The mean change of alignment was 1.2 degrees. There was no radiological evidence of stem loosening. One stem was revised due to a peri-prosthetic fracture. Cortical healing was noted in 11 hips, and trabecular incorporation in 10. CONCLUSION: Although intra- and post-operative complications were not uncommon, femoral IBG is a safe procedure in carefully selected patients and offers good medium-term results.

Anterior dislocation of Insall Burstein II total knee arthroplasty secondary to polyethylene tibial post fracture: a case report.

Anterior dislocation of a posterior stabilised total knee arthroplasty secondary to a polyethylene tibial post fracture is rare. We report one such case in an 89-year-old Chinese woman who had undergone total knee arthroplasty using the Insall Burstein II prosthesis 7 years earlier. The failure was due to sagittal malalignment of the components. Owing to more pronounced anterior bowing of the distal femoral shaft in southern Chinese, neutral component placement is often biased toward hyperextension. When the knee reaches full extension, anterior impingement occurs. Surgeons must therefore take extra care in preoperative planning and bone cutting in this population.