Emmanuel Thienpont

A systematic review and meta-analysis of patient-specific instrumentation for improving alignment of the components in total knee replacement

We conducted a meta-analysis, including randomised controlled trials (RCTs) and cohort studies, to examine the effect of patient-specific instruments (PSI) on radiological outcomes after total knee replacement (TKR) including: mechanical axis alignment and malalignment of the femoral and tibial components in the coronal, sagittal and axial planes, at a threshold of > 3º from neutral. Relative risks (RR) for malalignment were determined for all studies and for RCTs and cohort studies separately. Of 325 studies initially identified, 16 met the eligibility criteria, including eight RCTs and eight cohort studies. There was no significant difference in the likelihood of mechanical axis malalignment with PSI versus conventional TKR across all studies (RR = 0.84, p = 0.304), in the RCTs (RR = 1.14, p = 0.445) or in the cohort studies (RR = 0.70, p = 0.289). The results for the alignment of the tibial component were significantly worse using PSI TKR than conventional TKR in the coronal and sagittal planes (RR = 1.75, p = 0.028; and RR = 1.34, p = 0.019, respectively, on pooled analysis). PSI TKR showed a significant advantage over conventional TKR for alignment of the femoral component in the coronal plane (RR = 0.65, p = 0.028 on pooled analysis), but not in the sagittal plane (RR = 1.12, p = 0.437). Axial alignment of the tibial (p = 0.460) and femoral components (p = 0.127) was not significantly different. We conclude that PSI does not improve the accuracy of alignment of the components in TKR compared with conventional instrumentation.

Pain after knee arthroplasty: an unresolved issue

AbstractPurpose Despite the recent advances in the understanding of pain mechanisms and the introduction of new drugs and new techniques in the postoperative management, pain after total knee arthroplasty (TKA) is still an unresolved issue. It affects the quality of life and rehabilitation of an important percentage of patients undergoing TKA. The aim of this narrative review was to give an overview on pain mechanisms and multimodal pain management.MethodsA review of all peer-reviewed articles on pain after knee arthroplasty was performed by two reviewers. Recent articles on incisional pain mechanisms were included because of their importance in the understanding of postsurgical pain. Search was performed in Pubmed, Cochrane and Google Scholar data bases.ResultsPostsurgical pain mechanisms are based on both local and systemic inflammatory reactions. Peri-operative pain management starts with the anaesthetic technique and resides on a multimodal analgesia regimen. New concepts, drugs and techniques have shown their efficacy in reducing the severity of acute postoperative pain and the risk of developing chronic pain after TKA.ConclusionThis narrative review offers a clear overview of pain mechanism after knee arthroplasty and an understanding on how multimodal pain management can reduce the intensity and duration of pain after knee arthroplasty.Level of evidenceIV.

Total knee arthroplasty with patient-specific instruments improves function and restores limb alignment in patients with extra-articular deformity

BACKGROUND Restoring function and alignment when treating knee arthritis with a total knee arthroplasty (TKA) in patients who have an extra-articular deformity (EAD) from a malunion or with retained femoral hardware is a challenge. The normal anatomical landmarks are hard to find and difficult to use to obtain correct alignment. The procedure will be further challenged by angular deformity of the femur or tibia. A retrospective study was performed on a case series of patients with EAD or obliteration of the canal treated with patient-specific instruments (PSI). METHODS A multicenter retrospective review of 10 patients with multiplanar deformities in which the knee components were aligned with patient-specific instruments was performed. Outcome and alignment were studied. RESULTS At a mean follow-up of 3.4years, function improved from preoperative as evidenced by a mean increase in the KS pain score of 53 points, KS function score of 48 points and Oxford Score of 28 points (P<0.05). Flexion improved from 94° +/- 11° to 112° +/- 15° (P<0.05). Limb alignment was restored with a mean Hip-Knee-Ankle angle of 179.3° +/- 1.3° (P<0.05). Maximum outliers were 177° to 181°. An average tourniquet time of 75 +/- 9minutes (range, 62-83min) was observed. CONCLUSIONS The use of patient-specific instrumentation systems to perform TKA in patients without access to the intramedullary canal because of EAD or fixation devices, improved function and restored limb alignment. Mechanical alignment can easily be obtained with this technique by intra-articular correction of deformities under 20°. LEVEL OF EVIDENCE Level IV.

Can technology improve alignment during knee arthroplasty

Component malalignment remains a concern in total knee arthroplasty (TKA); therefore, a series of technologies have been developed to improve alignment. The authors conducted a systematic review to compare computer-assisted navigation with conventional instrumentation, and assess the current evidence for patient-matched instrumentation and robot-assisted implantation. An extensive search of the PubMed database for relevant meta-analyses, systematic reviews and original articles was performed, with each study scrutinised by two reviewers. Data on study characteristics and outcomes were extracted from each study and compared. In total 30 studies were included: 10 meta-analyses comparing computer-assisted navigation and conventional instrumentation, 13 studies examining patient-matched instrumentation, and seven investigating robot-assisted implantation. Computer-assisted navigation showed significant and reproducible improvements in mechanical alignment over conventional instrumentation. Patient-matched instrumentation appeared to achieve a high degree of mechanical alignment, although the majority of studies were of poor quality. The data for robot-assisted surgery was less indicative. Computer-assisted navigation improves alignment during TKA over conventional instrumentation. For patient-matched instrumentation and robot-assisted implantation, alignment benefits have not been reliably demonstrated. For all three technologies, clinical benefits cannot currently be assumed, and further studies are required. Although current technologies to improve alignment during TKA appear to result in intra-operative benefits, their clinical impact remains unclear, and surgeons should take this into account when considering their adoption.

Patellofemoral joint replacement, an evolving concept

Isolated patellofemoral arthritis is a rare disease, whose management is challenging and controversial. Patellofemoral joint replacement can be an effective treatment for this condition. The very concept of a patellofemoral implant has evolved throughout the years, resulting in more anatomic designs and reproducible surgical techniques. The clinical outcomes of this procedure are strictly related to surgical indications, implant design and appropriate surgical technique.

Uncertainties surrounding the choice of surgical treatment for 'bone on bone' medial compartment osteoarthritis of the knee

A number of different surgical interventions can be used for treating antero-medial osteoarthritis (AMOA) of the knee and this choice can present challenges for patients decision-making. Patients with AMOA can undergo Total Knee Replacement (TKR), Unicompartmental Knee Replacement (UKR) or High Tibial Osteotomy (HTO) for the same pathology. However many uncertainties still exist as to deciding which operation is best for individual patients and the Orthopaedic community has failed to systematically compare treatment options. The relative lack of scientifically based evidence has impacted on the ability to provide clear guidelines on treatment choice, patient suitability and direct patient preference for treatment. This paper, using available evidence, discusses the issue and offers some suggestions for future development.

Global Forum: An International Perspective on Outpatient Surgical Procedures for Adult Hip and Knee Reconstruction

Outpatient surgical procedures for adult hip and knee reconstruction are gaining interest on a worldwide basis and have been progressively increasing over the last few years. Preoperative screening needs to concentrate on both the patients comorbidities and home environment to provide a proper alignment of expectations of the surgeon, the patient, and the patients family. Preoperative multidisciplinary patient information covering all aspects of the upcoming treatment course is a mandatory step, focusing on pain management and early mobilization. Perioperative pain management includes both multimodal and preventive analgesia. Preemptive medications, minimization of narcotics, and combination of general and regional anesthesia are the techniques required in joint arthroplasty performed as an outpatient surgical procedure. A multimodal blood loss management program should be used with preoperative identification of anemia and attention directed toward minimizing blood loss, considering the use of tranexamic acid during the surgical procedure. Postoperative care extends from the initial recovery from anesthesia to the physical therapists evaluation of the patients ambulatory status. After the patient has met the criteria for discharge and has been discharged on the same day of the surgical procedure, a nurse should call the patient later at home to check on wound status, pain control, and muscle weakness, which will be further addressed by physiotherapy and education. Implementing outpatient arthroplasty requires monitoring safety, patient satisfaction, and economic impact.

Is knee function better with contemporary modular bicompartmental arthroplasty compared to total knee arthroplasty? Short-term outcomes of a prospective matched study including 68 cases

BACKGROUND Bicompartmental knee arthroplasty (BKA) was developed to treat medial tibiofemoral and patellofemoral osteoarthritis while preserving the anterior cruciate ligament to optimise knee kinematics. Our objective here was to compare the probability of achieving forgotten knee status and the functional outcomes at least two years after BKA versus total knee arthroplasty (TKA). We hypothesised that contemporary modular BKA produced better functional outcomes than TKA after at least two years, for patients with similar pre-operative osteoarthritic lesions. MATERIAL AND METHODS We conducted a two-centre prospective controlled study of 34consecutive patients who underwent BKA between January 2008 and January 2011. Each patient was matched on age, gender, body mass index, preoperative range of knee flexion, centre, and surgeon to a patient treated with TKA. An independent observer evaluated all 68 patients after six and 12months then once a year. Forgotten knee status was defined as a 100/100 value of the Forgotten Joint Score (FJS-12) and each of the five KOOS subscales. We also compared the two groups for knee range of motion, Knee Society Scores (KSSs), Timed Up-and-Go test (TUG), and UCLA Activity Score. RESULTS At a mean follow-up of 3.8±1.7 years, the probability of forgotten knee status was significantly higher in the BKA group (odds ratio, 4.64; 95% confidence interval, 1.63-13.21; P=0.007, Chi(2) test). Mean post-operative extension was not significantly different between the groups, whereas mean range of knee flexion was significantly greater in the BKA group (130°±6° vs. 125°±8° after TKA; P=0.03). The BKA group had significantly higher mean values for the knee and function KSSs, TUG test, and UCLA score (P<0.04 for all four comparisons). CONCLUSION After at least two years, contemporary unlinked BKA was associated with greater comfort during everyday activities (forgotten knee) and better functional outcomes, compared to TKA. These short-term results require validation in randomised trials with longer follow-ups. LEVEL OF EVIDENCE III, case-control study.

Bone morphotypes of the varus and valgus knee

BackgroundCoronal deformity correction with total knee arthroplasty (TKA) is an important feature in the treatment of osteoarthritis (OA). The hypothesis of this study was that bone morphology would be different in varus and valgus deformity, both before osteoarthritis development as well as during and after the disease process of OA.Materials and methodsRetrospective study with measurements on preoperative and postoperative full leg standing radiographs of 96 patients who underwent TKA. The included patients were selected for this study because they had an OA knee on one side and a non-arthritic knee on the contralateral side presenting the same type of alignment as the to-be-operated knee (varus or valgus alignment on both sides). The control group of 46 subjects was a group of patients with neutral mechanical alignment who presented for ligamentous problems. A single observer measured mechanical alignment, anatomical alignment, anatomical–mechanical femoral angle and intra-articular bone morphology parameters with an accuracy of 1°.ResultsVarus OA group has less distal femoral valgus (mLDFA 89°) than control group (87°) and valgus OA group (mLDFA 85°). Varus OA group has same varus obliquity as control group (MPTA 87°) but more than valgus OA group (MPTA 90°). Joint Line Congruency Angle (JLCA) is 3°open on lateral side in varus and medially open in valgus OA group (2°). The non-arthritic valgus group presents a constitutional mechanical valgus of 184° Hip–Knee–Ankle (HKA) angle.DiscussionVarus deformity in OA as measured with an HKA angle (HKA) <177° is a combination of distal femoral wear, tibial varus obliquity and lateral joint line opening. Valgus deformity in OA with an HKA > 183° is a combination of femoral distal joint line obliquity and wear combined with medial opening due to medial collateral ligament stretching. The clinical importance of bone morphotype analysis is that it shows the intra-articular potential of alignment correction when mechanical axis cuts are performed.ConclusionBone morphology in varus and valgus deformity is different before and after osteoarthritis. Perpendicular cuts to mechanical axes do not necessarily lead to neutral mechanical axis. Constitutional mechanical valgus was observed as 184° HKA angle before the development of OA.Level of evidenceLevel IV study.

Efficacy of Patient-Specific Instruments in Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

Background: Patient-specific instrumentation (PSI) was introduced with the aim of making the procedure of total knee arthroplasty more accurate and efficient. The purpose of this study was to compare PSI and standard instrumentation in total knee arthroplasty with regard to radiographic and clinical outcomes as well as operative time and blood loss. Methods: A meta-analysis was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. PubMed and Embase were searched from 2011 through 2015. We included randomized controlled trials and cohort studies that reported the effect of PSI on the aforementioned outcomes. The primary end point was deviation from the mechanical axis by >3°. Random and fixed-effect models were used for analysis. Results: A total of 44 studies, which included 2,866 knees that underwent surgery with PSI and 2,956 knees that underwent surgery with standard instrumentation, were evaluated. The risk of mechanical axis malalignment was significantly lower for PSI, with a pooled relative risk of 0.79 (p = 0.013). The risk of tibial sagittal-plane malalignment was higher for PSI than for standard instrumentation (relative risk = 1.32, p = 0.001), whereas the risk of femoral coronal-plane malalignment was significantly lower (relative risk = 0.74, p = 0.043). The risk of tibial coronal-plane malalignment was significantly higher for PSI only when employing fixed-effect meta-analysis (relative risk = 1.33, p = 0.042). Minor reductions in total operative time (−4.4 minutes, p = 0.002) and blood loss (−37.9 mL, p = 0.015) were noted for PSI. Conclusions: PSI improves the accuracy of femoral component alignment and global mechanical alignment, but at the cost of an increased risk of outliers for the tibial component alignment. The impact of the increased probability of tibial component malalignment on implant longevity remains to be determined. Meta-analyses indicated significant differences with regard to operative time and blood loss in favor of PSI. However, these differences were minimal and, by themselves, not a substantial justification for routine use of the technology. Level of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.