Pierre-Emmanuel Schwab

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.

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.

The use of patient-specific instruments does not reduce blood loss during minimally invasive total knee arthroplasty?

AbstractPurposeBlood loss can be substantial and will influence morbidity and mortality after total knee arthroplasty. This study evaluated whether patient-specific instruments (PSI) can reduce blood loss because the intramedullary canal is not opened during the procedure and whether hidden blood loss can be reduced by its use.MethodsSeventy-five patients operated with the Signature PSI technique were compared with a matched group operated with conventional instruments. Maximal drop in haemoglobin (Hb) and hematocrit (HTC) level were compared at day 2 and day 4. Transfusions were noted. Clinical outcomes like range of motion and knee society scores were studied as secondary outcomes.ResultsNo statistically significant difference for calculated blood loss, maximal drop in Hb or HTC and transfusions were found. No clinical differences in range of motion or knee society scores were observed.ConclusionsThe use of PSI-assisted total knee arthroplasty (TKA) did not result in less blood loss compared with conventional minimally invasive TKA with tourniquet. No reduction in hidden blood loss was observed either. According to this study, the argument of reduced transfusion cost should not be used in cost-effectiveness calculations of PSI-assisted TKA.Level of evidenceIII.

Wear patterns in anteromedial osteoarthritis of the knee evaluated with CT-arthrography

OBJECTIVE To analyze the value of CT-arthrography imaging in the diagnosis of knee osteoarthritis and to facilitate the selection of partial versus total knee replacement. METHODS A retrospective study of 100 patients that had either medial unicompartmental knee replacement (UKR) (N=50) or total knee replacement (TKR) (N=50). One observer measured lower limb mechanical alignment and osteoarthritis patterns of the knee in each compartment with radiographs, CT-arthrography and full leg standing radiographs. RESULTS All patients had Kellgren-Lawrence grade IV osteoarthritis of the medial femorotibial joint with a mean (SD) varus alignment of the lower limb (172° (3.5°) HKA-angle). Zone mechanical axis distribution showed strong correlation with HKA-axis. Arthritis patterns were different for patients selected for UKR or TKR. UKR patients had anteromedial osteoarthritis and wear of the medial facet of the patella in contrast to TKR patients who had medial osteoarthritis associated with diffuse or lateral patellofemoral wear and wear of the central or posterior zones of the lateral compartment. Medial facet wear of the patella is related to more important varus alignment of the lower limb (Kennedy zone 0 and 1). CONCLUSION CT-arthrography imaging can show lesions that are not visible on plain or stress radiographs because of central or posterior localization with surrounding intact cartilage. Patients who develop tri-compartmental osteoarthritis despite varus alignment have probably other risk factors than their mechanical alignment and should be considered candidates for TKR.

Use of a haemostatic matrix (Floseal®) does not reduce blood loss in minimally invasive total knee arthroplasty performed under continued aspirin

BACKGROUND Aspirin is being used for primary and secondary cardiovascular prevention. It has been proposed that aspirin should be discontinued 5 to 7 days before surgery. However, discontinuation might increase the risk of cardiac and thrombo-embolic co-morbidity. Aspirin also increases the risk of bleeding during and after total knee arthroplasty. This study evaluated if the intra-articular use of a haemostatic matrix (Floseal®) might decrease blood loss in total knee arthroplasty performed under continued aspirin use. MATERIALS AND METHODS We retrospectively compared matched pairs in two groups (80 patients in each group). Patients in both groups were taking aspirin: one group was managed with conventional haemostasis (with bovie electrocoagulation), while the other group was treated with an intra-articular haemostatic matrix as an adjunct to electrocoagulation. The outcomes compared were haemoglobin and haematocrit levels at days 2 and 4 after surgery as surrogates for blood loss, transfusion rate, surgical time, and length of stay in the hospital. RESULTS No differences were observed between the two groups for haemoglobin and haematocrit levels on days 2 and 4. There were no differences in transfusion rate, surgical time or length of stay in hospital between the two groups. DISCUSSION The present study shows that the use of Floseal® has no effect on reducing either visible or hidden blood loss after total knee arthroplasty with peri-operative continuation of aspirin use, as assessed by a drop in haemoglobin or haematocrit.

Use of a haemostatic matrix does not reduce blood loss in minimally invasive total knee arthroplasty

BACKGROUND Blood loss can increase morbidity and the risk of transfusion after total knee arthroplasty (TKA). This study evaluated the difference in blood loss between minimally invasive TKA performed with and without intra-articular use of a haemostatic matrix (Floseal®). MATERIALS AND METHODS We retrospectively compared matched pairs in two groups (76 patients in each group): one group received conventional haemostasis (with bovie electrocoagulation), the other group was treated with an intra-articular haemostatic matrix (HM) as an adjunct to electrocoagulation. The outcomes compared were haemoglobin (Hb) and haematocrit levels at days 2 and 4 after surgery as a surrogate for blood loss, transfusion rate, surgical time, preoperative and postoperative range of motion (ROM) at days 21 and 42 and length of stay (LOS) in hospital. RESULTS No differences were observed for Hb levels at day 2 or day 4 between men in the two groups. In women, however, the mean Hb at day 2 was 11.1 g/dL (SD 1.3) for TKA with HM and 12.0 g/dL (SD 0.9) for TKA without HM (p<0.001), while that at day 4 was 10.6 g/dL (SD 1.3) for TKA with HM and 11.4 g/dL (SD 1.2) for TKA without HM (p<0.001). The haematocrit was higher for TKA without HM at day 2 (p=0.001) and day 4 (p=0.008). The transfusion rate for TKA with HM was 2.6% and for TKA without HM 0% (p=0.497), while the mean surgical time was 93 minutes (SD 12) vs 87 minutes (SD 14), respectively (p=0.0055). There were no differences in preoperative or postoperative ROM at days 21 and 42 between the two groups. The LOS was longer for TKA with HM than for TKA without HM (4.5 days and 4 days, respectively, p=0.011) influenced by the longer stay for the transfused patients. DISCUSSION The present study showed that the use of Floseal had no effect on reducing either visible or hidden blood loss after TKA, as assessed by a drop in Hb or haematocrit and that hidden blood loss was more important in women treated with the HM.