Pelvic flexion/extension and its impact on functional acetabular alignment and stability following total hip replacement.

PURPOSE: Dislocation following total hip arthroplasty (THA) remains a significant clinical problem and can occur even with optimal implant alignment. We hypothesized that different patterns of pelvic flexion/extension (PFE) during daily activities may influence acetabular alignment and contribute to impingement and instability following THA. Recently, there has been an increased interest in spinopelvic alignment and its impact on THA. Therefore, this study aimed to identify different patterns of PFE that could be predictive of instability following THA. METHODS: A range of motion (ROM) simulator was used to demonstrate the effects of different patterns of PFE on ROM and impingement. The findings were applied to PFE measurements obtained from 84 patients in standing and sitting positions. RESULTS: Three different categories of PFE were identified: normal, hypermobile, and stiff. ROM simulator revealed that changes in PFE had affected ROM and impingement significantly. Patients in the stiff pelvis category, even with "optimal" implant alignment, were more susceptible to implant impingement. CONCLUSIONS: The different patterns of PFE during daily activities could affect acetabular alignment and stability following THA. We propose a classification system that can identify different types of PFE and predict their effects on the stability of prostheses following THA. Hence, we believe that patients with unfavorable PFE may require modified cup alignment.

The difference in leg lengths following total knee replacement for patients with severe osteoarthritic deformity.

PURPOSE: Increased height after total knee replacement surgery (TKR) may offer patients higher satisfaction as well as the quality of life. Therefore, in this paper, we aim to document the changes in leg length after TKR in patients with severe bilateral deformities. METHODS: The data of 61 patients were collected from the Egyptian Community Arthroplasty Register; of them, 21 patients had unilateral TKR while 40 had bilateral simultaneous TKR. The patterns of changes in height of 101 osteoarthritic knees were followed up for 1 year after having TKR. All patients had standing leg X-rays, before and after surgery, to document the length of the femur and tibia before and after TKR. Correlations were assessed using the two-sample t-test. RESULTS: The sample was mostly females (56/61, 91.8%). The distribution of the operated side was nearly equal (right knee was 47/101, 46.5%). The overall average leg length difference was 5.4 (SD = 2.3); for the unilateral group, the average was 4.6 (SD = 2.6); and for the bilateral group, the average was 5.6 (SD = 2.3), p = 0.119. We found that leg length may differ according to the varus deformity angle (p < 0.001) as well as fixed flexion deformity (p < 0.001). CONCLUSIONS: Leg length increased significantly 1 year after TKR. However, there is not enough evidence to suggest that the bilateral group had a greater height increase when compared to the unilateral group.

Learning curve of the 67 steps of conventional total knee replacement: an experimental study.

The instrumentation system for total knee replacement (TKR) has been there since the 1970s. The many steps and instruments are the main features despite several modifications over the last 50 years. This may lead to the accumulation of errors as certain steps are dependent on others. This study aimed to identify the errors while performing TKR by three trainees at different levels of training. Methods: Three trainees with different expertise performed the steps of TKR on bone models. One senior supervisor recorded the outcomes, including operative time and errors made during the experiment. Errors were further categorized into correctable and uncorrectable ones. Results: Most of the errors were made by the trainee with the least experience during the stages of femoral cutting, sizing, and rotation. The first-year resident has taken 1.25 times longer than the fellow in preparing the femur and 1.11 times in preparing the tibia. The recorded mistakes were 28, 8, and 3 for the first-year resident, the second-year resident, and the fellow surgeon, respectively. Fifteen of the mistakes were uncorrectable, and none of them were from the senior surgeon. Conclusion: The results of this study highlight the type of errors made by different trainees. This shows the steep learning curve of conventional instrumentation systems for trainees. Increasing cognitive skills and applying computer-assisted technologies may help trainees overcome this steep learning curve.

The rate and management of prosthetic joint infection in the low-income setting: a cross-sectional study.

Although the rate of prosthetic joint infection (PJI) after total hip and knee arthroplasties (THA and TKA, respectively) is well documented in developed countries, there is a paucity of information in the literature on infection rates in low-and-middle-income countries. This study aims to review the PJI rate and management based on the Egyptian Community Arthroplasty Registry (ECAR) and six arthroplasty surgeons. Methods: Using data from the ECAR, for over 10 years, and surveying six high-volume arthroplasty surgeons, we reviewed the infection rate, common organisms, antibiotics used, and how the revision surgeries were done. The total number of patients included in this study was 210 infection cases out of 5216 THA and TKA. Results: Out of the 5216 joint replacement surgeries, the rate of all infections in THA and TKA was 4.03% (4.73 and 2.94%, respectively). The rate of infections requiring staged revision surgeries was 2.24 and 1.71% (2.03% in total) in the THA and TKA groups, respectively. The most encountered organism was Staphylococcus aureus. The common antibiotics used were vancomycin and a combination of cefoperazone and sulbactam. Conclusion: From this study, we conclude that THA was associated with a higher rate of PJI, surgeons' use of antibiotics for a relatively long period, and the rate of PJI in our setting is relatively higher than what is reported in developed countries but lower in other low-income settings. We believe that with improved operating theater design and infection control education, infection rates will decrease significantly. Finally, we acknowledge the need for a national arthroplasty registry that can help in documentation and improving patient outcomes.

Comparison of Functional Outcome of Total and Unicompartmental Knee Arthroplasty Using Computer-Assisted Patient-Specific Templating.

BACKGROUND: Knee arthroplasty surgeries are in ever-increasing demand. With unicompartmental knee arthroplasty (UKA), patients may benefit from a higher range of flexion and a better Knee Society Score (KSS). AIM: In this study, we compared the short-term clinical outcomes of total knee arthroplasty (TKA) and UKA using the patient-specific templating (PST) technique. METHODS: Two groups of 20 knees each were divided into UKA and TKA groups depending on the Oxford criteria of UKA. Only patients with medial compartmental osteoarthritis were included. KSS, functional knee score (FKS), and ROF were assessed preoperatively and at 6 months postoperatively. RESULTS: The TKA group has shown a significant improvement compared to the UKA group in KSS (MD = 39.35 vs. 31.2, respectively, p=0.003). Both TKA and UKA have shown no significant difference concerning both the FKS (MD = 32 and 31.75, respectively, p=0.926) and ROF (MD = 10.25 and 7.25, respectively, p=0.072). Discussion. The higher improvement of KSS in the TKA group can be attributed to the fact that patients in the TKA had significantly worse KSS preoperatively. Also, the small improvement in ROF in the UKA group might be related to their wider preoperative ROF. CONCLUSION: Preoperatively, the TKA group had lower KSS and ROF compared to UKA. The improvement of KSS from preoperative to postoperative was more significant in TKA. However, the TKA group has shown less range of flexion postoperatively.

Satisfactory Outcome for a Challenging Case of Infected Native Pelvic Discontinuity with Significant Bone Loss: A Case Report.

CASE: This is a challenging case of infected native pelvic discontinuity with massive acetabular bone loss. The infection was persistent despite repeated debridement. A new technique of articulated antibiotic spacer plus Mexican hat antibiotic spacer has been used. A triflanged custom-made implant was used in the second-stage surgery. The 2-year follow-up showed no recurrence of infection and no loosening. CONCLUSION: Using a Mexican hat spacer is a good option when there is a massive bone loss medially. Custom-made triflanged cup showed to be a viable treatment modality for infected pelvic discontinuity despite the cost of the implant.

The W.A.I.O.T. Definition of Peri-Prosthetic Joint Infection: A Multi-center, Retrospective Validation Study.

Peri-prosthetic joint infection (PJI) definition plays an important role in diagnostic and therapeutic decisions. However, while several criteria have been proposed by eminent institutions to define a PJI in the last decade, their clinical validation has been rarely performed. Aim of the present multicenter, international, retrospective study was to validate the World Association against Infection in Orthopedics and Trauma (WAIOT) pre/intra-operative PJI definition with post-operative confirmatory tests. A total of 210 patients, undergoing hip (n = 86) or knee (n = 124) revision surgery for any reason in six orthopedic centers in Africa, Asia, Europe and South America, were retrospectively evaluated at a two years minimum follow-up after surgery. All the available pre-, intra- and post-operative findings were collected and analyzed according to the WAIOT criteria, which include a set of tests to confirm (Rule In) or to exclude (Rule Out) a PJI. On average, patients were investigated pre/intra-operatively with 3.1 ± 1.1 rule out and 2.7 ± 0.9 rule in tests; the presence of a fistula or exposed implant was reported in 37 patients (17.6%). According to pre/intraoperative findings, 36.2% of the patients were defined as affected by high-grade PJI (n = 76; average score: 2.3 ± 0.8), 21.9% by low-grade PJI (n = 46; average score: 0.8 ± 0.8), 10.5% by biofilm-related implant malfunction (n = 22; average score: -1.6 ± 0.8), 2.9% as contamination (n = 6; average score: -3.5 ± 1.0), and 28.6% as no infection (n = 60; average score: -3.0 ± 1.4). Pre/intra-operative PJI definitions matched post-operative confirmatory tests, in 97.1% of the patients. This is, to our knowledge, one of the largest study ever conducted to validate a PJI definition The retrospective analysis in different centers was greatly facilitated by the structure of the WAIOT definition, that allows to include different tests on the basis of their sensitivity/specificity, while the comparison between pre/intra-operative and post-operative findings offered the internal validation of the scoring system. Our results authenticate the WAIOT definition as a reliable, simple tool to identify patients affected by PJI prior to joint revision surgery.

Hospital-based Patient-specific Templates for Total Knee Arthroplasty: A Proof of Concept Clinical Study.

INTRODUCTION: All available patient-specific instruments or patient-specific templates (PSTs) are controlled by implant companies. Most of these companies outsource some of the steps of the PST such as imaging, preoperative planning, manufacturing of PST, and packing/sterilization. This is a proof of concept clinical study on the hospital-based PST system for total knee arthroplasty (TKA). METHODS: A total number of 257 TKA procedures were performed on the basis of a new concept of hospital-based PSTs. All 5 steps of the PST [ie, imaging (computed tomographic scanning), planning, PST production, packing/sterilization, and surgery] were performed by the hospital. All cases included in this work are documented in the Egyptian Community Arthroplasty Register. RESULTS: All cases had their surgeries performed without resorting to conventional intramedullary guides. Computed tomography-based imaging was easy and affordable. Planning was controlled by the surgeon. Polyamide nylon was the best available material and it was autoclavable. Desktop 3-dimensional printers were able to produce PSTs made of nylon, but it was difficult and time consuming. Industrial printers were superior in quality to desktop printers but more expensive. The whole process could be performed in as short a duration as 3 working days. CONCLUSIONS: Hospital-based PST was feasible and it was facilitated by the introduction of desktop 3-dimensional printers. This technique was less expensive and more time saving than commercially available PSTs as well as the conventional TKA.

Patient-specific instruments: advantages and pitfalls.

Patient-specific instruments (PSI) aim to improve the accuracy of total knee replacement (TKR) based on computer-assisted preoperative planning. In this work, the authors describe the advantages and pitfalls of PSI based on their clinical experience. The main conclusion of this work is that PSI has direct impact on the logistical and technical features of TKR with some advantages and pitfalls.

Anthropometry of Arabian Arthritic Knees: Comparison to Other Ethnic Groups and Implant Dimensions.

BACKGROUND: We aim to measure the proximal tibia and distal femur of the osteoarthritic knees of Arab patients and to compare these measurements with data on other ethnic groups available in literature and with the dimensions of 6 knee implants. METHODS: Anteroposterior and mediolateral measurements of tibia and femur were done on 3-dimensional computed tomography reconstructions of 124 osteoarthritic knees undergoing total knee arthroplasty with patient-specific instruments. RESULTS: Average mediolateral and anteroposterior dimensions of the tibia for Arab knees were 74.36 ± 6 mm and 48.94 ± 4.57 mm, respectively, whereas for femur, 72.04 ± 6.6 and 68.1 ± 7.75, respectively. Average aspect ratio for tibial was 152.62 ± 12.66 and for femur 106.37 ± 14.34. CONCLUSION: The size of Arab knees was generally smaller than Caucasian and larger than Asian. There is significant asymmetry of proximal tibial plateau and femur condyles.

Digital templating for THA: a simple computer-assisted application for complex hip arthritis cases.

INTRODUCTION: Total hip arthroplasty (THA) is the standard procedure for end-stage arthritis of the hip. Its technical success relies on preoperative planning of the surgical procedure and virtual setup of the operative performance. Digital hip templating is one methodology of preoperative planning for THA which requires a digital preoperative radiograph and a computer with special software. PATIENTS AND METHODS: This is a prospective study involving 23 patients (25 hips) who were candidates for complex THA surgery (unilateral or bilateral). Digital templating is done by radiographic assessment using radiographic magnification correction, leg length discrepancy and correction measurements, acetabular component and femoral component templating as well as neck resection measurement. RESULTS: The overall accuracy for templating the stem implant's exact size is 81%. This percentage increased to 94% when considering sizing within 1 size. CONCLUSION: Digital templating has proven effective, reliable and essential technique for preoperative planning and accurate prediction of THA sizing and alignment.

Is fixation an option for comminuted femoral head fracture?

Femoral head fracture (Pepkin fracture) is a serious injury that is usually caused by trauma with more incidences in young age. There is no definitive treatment suggested in literature for Pepkin fracture. In this work, a case with class IV Pipkin fracture is presented. Fixation of the fracture was done and the outcomes of the surgical procedure immediately and 6 years after surgery are documented.

Highlighting the medical applications of 3D printing in Egypt.

Computer-assisted designing/computer-assisted manufacturing (CAD/CAM) technology has enabled medical practitioners to tailor physical models in a patient and purpose-specific fashion. It allows the designing and manufacturing of templates, appliances and devices with a high range of accuracy using biocompatible materials. The technique, nevertheless, relies on digital scanning (e.g., using intraoral scanners) and/or digital imaging (e.g., CT and MRI). In developing countries, there are some technical and financial limitations of implementing such advanced tools as an essential portion of medical applications. This paper focuses on the surgical and dental use of 3D printing technology in Egypt as a developing country.

Gluteal Compartment Syndrome following Vascular and Neurological Injuries.

Gluteal compartment syndrome is a serious but rare condition that has recently been increasingly reported in literature. This report presents two cases that followed neurological and vascular injuries (first case: an injury of the superior gluteal artery; second case: neurological injury bilaterally). A high index of suspicion and attention is needed to early diagnose this condition due to the possibility of developing serious and potentially fatal complications and difficulty in management.

We need a break: Bisphosphonates.

Bone is a dynamic tissue. It remodels, thereby maintaining serum calcium, repairing micro damage and maintaining strength. A reduction in the strength of bone leads to osteoporosis that may manifest clinically as low energy vertebral and non-vertebral fractures. The bone strength, in turn, is determined by its material, structural properties and on its remodeling potential. Commonly, osteoporosis is objectively evaluated by 'T' and 'Z' scores and these are the indicators of bone density as determined by Dexa scan; these scores correlate inversely with the fracture risk. Quite often, we forget that Dexa scan results are not the only factors determining bone strength and the association between bone density and bone strength is not fixed, and is exemplified by the example of "osteopetrosis". The same issue is happening with the prolonged use of bisphosphonates (BP's).

The use of computer-assisted orthopaedic surgery in complex cases of hip and knee arthroplasty: experience from a developing country.

The technology of computer-assisted orthopaedic surgery (CAOS) has been used in many developed countries for the last two decades. Initially, it was thought that CAOS would be the standard in surgical practice, but so far its clinical application has been limited due to the involved cost and complexity. The cost-effectiveness of CAOS techniques has also been questioned. Therefore, it is expected that the application of CAOS in developing countries would be more limited for the same reasons. Herein, the author presents a surgical experience of using different CAOS techniques in Egypt. Computer-assisted templating software was used in complex and neglected cases of hip arthritis and in cases of leg length discrepancy. Navigation techniques were employed in knee arthroplasty in patients with extraarticular deformities. Computer-assisted patient-specific instruments were used for bilateral simultaneous knee arthroplasty in medically unfit patients and in patients with severe articular deformities. Contrary to expectations, the experience proved that CAOS is more useful and possibly cost-effective when used in hip and knee arthroplasty for complex and neglected cases in developing countries.

Functional pelvic orientation measured from lateral standing and sitting radiographs.

We prospectively obtained preoperative and 3-month postoperative lateral pelvic radiographs in the standing and sitting positions from 84 patients who underwent total hip arthroplasty. We measured pelvic orientation (flexion extension) using the anterior pelvic plane as defined by the anterior superior iliac spines and pubic tubercles as references. There was a trend towards upright pelvic alignment when standing, with a mean anterior pelvic plane angle of 1.2 degrees (range, -22 degrees - +27 degrees). In the sitting position the pelvis tended to extend posteriorly, with a mean anterior pelvic plane angle of -36.2 degrees (range, -64 degrees - +4 degrees). There was a wide variation in the arc of pelvic flexion extension as patients moved from standing to sitting, with are of pelvic motion in some patients as mobile as 70 degrees and in others as stiff as 5 degrees. There was no significant variation between males and females or between preoperative and postoperative pelvic flexion extension. There were substantial variations in pelvic orientation when comparing standing and sitting for an individual patient and between different patients. This variation can be unpredictable, and may influence implant alignment and stability after total hip arthroplasty.

Accuracy of pelvic flexion measurements from lateral radiographs.

Variations in pelvic orientation affect preoperative planning decisions, intraoperative navigation, and postoperative measurements. By providing the means to measure pelvic flexion at low cost and reporting pelvic flexion using the standard reference system, a lateral radiograph technique based on the pubic tubercles and anterior superior iliac spines may be useful for studying functional pelvic orientation and functional alignment and for improving accuracy of postoperative measurement. We evaluated the accuracy of this method by synthesizing 50 lateral pelvic radiographs. Six observers performed manual landmark-based pelvic flexion measurements on the resultant radiographs. Pelvic flexion measurement errors were small (0.004 masculine +/- 1.38 masculine). Apart from one outlier with an error of 12.4 masculine, the errors ranged from -4.0 masculine to 3.0 masculine. The data suggest that accurate measurements of pelvic flexion can be made from lateral radiographs with respect to the standard anatomic reference system. However, failure to correctly observe a landmark can introduce large errors. Therefore, the clarity of the relevant landmarks should be considered carefully before applying this technique. Lateral radiographs can be easily acquired and analyzed, making this technique convenient and inexpensive.

Three-dimensional planning and virtual radiographs in revision total hip arthroplasty for instability.

Instability is one of the most challenging complications of total hip arthroplasty. The cause of instability is not always clear and treatment outcome is not always satisfactory. Treatment can be optimized by accurate identification of the cause of instability and precise surgical technique. In this case report, we illustrate the use of a three-dimensional (3-D) preoperative planner and virtual radiographic system to improve component position in revision total hip arthroplasty required because of recurrent dislocation. Using this technique, we identified common problems seen in patients with unstable hips after previous revision surgery including impingement, cup malpositioning, bone deficiency in the medial wall, and integrity of fixation screws. The computer-assisted system allowed preoperative planning with range of motion simulation and optimization of the acetabular cup position. The virtual radiographic system provided 3-D measurement of the cup position using a postoperative plane radiograph.