Are Proud Tibial Cone Constructs an Effective Alternative to Those That are Fully Seated in Revision Total Knee Arthroplasty?

BACKGROUND: This study compared the clinical, radiographic, and patient-reported outcomes between patients treated with the traditional fully seated tibial cone construct and those with the novel proud tibial cone construct in revision total knee arthroplasty (rTKA). METHODS: This was a retrospective study of 56 adult patients who had a minimum 2-year follow-up and underwent rTKA with either the fully seated (n = 18 knees) or proud (n = 42 knees) tibial cone construct between 2010 and 2020. The electronic medical record was reviewed for demographic, clinical, and radiographic data. Knee Injury and Osteoarthritis Outcome Scores (KOOS) were collected. RESULTS: All patients had improved mechanical alignment postoperatively regardless of surgical technique. All patients showed good evidence of osseointegration without loss of fixation at the latest follow-up. There were no significant differences in the complication rate or re-revision rate between the groups. KOOS Function in Sport and Recreation (Sport/Rec) scores were significantly higher for patients treated with the fully seated construct (mean 57 [range, 20 to 95] versus 38 [range, 0 to 75], P = .04); however, no significant differences were present for the other KOOS subscales or KOOS Jr. CONCLUSION: The proud tibial cone construct may be an effective alternative to the fully seated construct in the setting of severe bone loss in rTKA. The proud construct avoids a proximal tibial cut, and thus is a bone-preserving technique that provides good fixation, reduces operative time, prevents potential iatrogenic injuries, decreases the need for tibial augments, saves costs, and improves the ease of restoring joint height.

Flexion Space Balancing Through Component Positioning and Its Relationship to Traditional Anatomic Rotational Landmarks in Robotic Total Knee Arthroplasty.

BACKGROUND: The use of the femoral component position to balance the flexion space and its relationship to the transepicondylar axis (TEA) and posterior condylar angle (PCA) has not been thoroughly evaluated. METHODS: A total of 233 patients undergoing robotic arm-assisted total knee arthroplasty were evaluated. Native TEA and PCA were established on preoperative computed tomography scans. Femoral component rotation was set in the axial plane to match the native trochlea and native medial femoral condyle to set the flexion gap. Knee flexion space gaps and component position were recorded. The relationship of the femoral component to the native TEA, PCA, and preoperative radiographic landmarks was evaluated. RESULTS: The intraoperative measured medial flexion space gap did not significantly correlate with the relationship of the femoral component to the PCA or TEA in varus or valgus knees. In varus knees, the preoperative mechanical axis alignment had a positive relationship to femoral component position when compared to the PCA (P = .04) and TEA (P = .002). In valgus knees, there was a positive correlation between the preoperative lateral distal femoral angle and component position when compared to the PCA (P = .04) only. CONCLUSION: Intraoperative measured flexion space balance through femoral component positioning did not correlate with its relationship to the native TEA or PCA. In varus knees, the preoperative mechanical axis alignment correlated with an increase in femoral component external rotation to the TEA and PCA. In valgus knees, the severity of preoperative lateral distal femoral angle correlated with the rotational relationship of the femoral component to the PCA only.

Bone morphogenic protein-2 use in revision total hip arthroplasty with acetabular defects.

INTRODUCTION: The restoration of acetabular bone stock during revision hip arthroplasty remains a challenge. There have been no clinical series reporting the efficacy of bone morphogenic protein-2 (rhBMP-2) in the revision hip setting. METHODS: We retrospectively reviewed the radiographs and records of 15 patients who received rhBMP-2 mixed with allograft bone chips (+BMP), and 14 who received allograft bone chips alone (-BMP) for their acetabular defect during revision total hip arthroplasty with a mean two-year follow up. Radiographs were evaluated for acetabular defect size, superior cup migration, and changes in the lateral cup abduction angle. Modified Harris hip scores were used for evaluation of clinical outcomes. RESULTS: Patients in the +BMP group compared to the -BMP group had significantly larger amounts of cancellous bone chips used (72.1 ± 35.5 cc vs. 38.6 ± 14.1 cc; p = 0.003). Mean rhBMP-2 used per case was 7.4 ± 3.1 mg in the +BMP group. Three patients in the -BMP group had cup migration which was not observed in the +BMP group. Mean Harris hip scores (HHS) improved post-operatively in both groups (40.1 ± 20.9 to 71.9 ± 19, p < .0001). No local adverse reaction was noted in the +BMP group. CONCLUSION: rhBMP-2 had modest clinical benefit in the setting of revision THA. Cost of this synthetic biologic versus the added clinical benefit should be carefully considered when being used in the revision hip setting.

Extensor Mechanism Centralization Using Autograft Hamstring for Laterally Dislocating Patella.

Patellofemoral complications following total knee arthroplasty (TKA) are some of the most commonly cited complications in the literature, accounting for up to 50% of secondary procedures in the literature. Lateral dislocation of the patella, while rare, is one of many causes of extensor mechanism dysfunction. We sought to evaluate a novel patellar centralization procedure by comparing patients' pre- and postoperative clinical and radiographic data. A retrospective case-series study was performed on 12 patient knees (5 male and 7 female) presenting with ambulatory dysfunction due to laterally dislocating patella. All of the knees had component revision combined with hamstring autograft tendon weave and medial reefing of the retinaculum and vastus medialis. The results revealed reliable stabilization of the patella and improved extensor lag at a mean 2.2±2.2 years' short-term follow-up, which correlated with improved postoperative radiographic measurements. Range of motion in both flexion and extension was improved postoperatively. Improvements in radiographic measures of patellar tilt and patellar displacement were statistically significant, with reductions in the mean patellar tilt from 41.5°±25.9° to 3.9°±13.7° (P=.004), and in the mean patellar displacement from 2.8±2.1 cm to 0.8±0.9 cm (P=.012). Our study findings support the use of the extensor mechanism centralization procedure with autograft hamstring in management of laterally dislocating patella after TKA. [Orthopedics. 2023;46(3):e186-e188.].

Cementless acetabular revision: past, present, and future. Revision total hip arthroplasty: the acetabular side using cementless implants.

BACKGROUND: Acetabular revision is probably the most difficult aspect of hip reconstructive surgery. Although the majority of acetabular revisions can be performed using an uncemented hemispherical acetabular device with ancillary fixation, patients with severe acetabular deficiencies and poor bone quality require more complex alternatives for revision. The limitations of traditional cementless acetabular implants has promoted the development of improved methods of fixation and revision techniques. Highly porous metals have been introduced for clinical use in arthroplasty surgery over the last decade. Their higher porosity and surface friction are ideal for acetabular revision, optimising biological fixation. The use of trabecular metal cups in acetabular revision has yielded excellent clinical results. PURPOSE: This review focuses on the use of cementless implants for acetabular revision. The use of trabecular metal cups, augments, jumbo cups, oblong cups, cages, and structural grafting are also discussed.

Expansion of myeloid-derived suppressor cells contributes to metabolic osteoarthritis through subchondral bone remodeling.

BACKGROUND: Osteoarthritis (OA) subsequent to acute joint injury accounts for a significant proportion of all arthropathies. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of myeloid progenitor cells classically known for potent immune-suppressive activity; however, MDSCs can also differentiate into osteoclasts. In addition, this population is known to be expanded during metabolic disease. The objective of this study was to determine the role of MDSCs in the context of OA pathophysiology. METHODS: In this study, we examined the differentiation and functional capacity of MDSCs to become osteoclasts in vitro and in vivo using mouse models of OA and in MDSC quantitation in humans with OA pathology relative to obesity status. RESULTS: We observed that MDSCs are expanded in mice and humans during obesity. MDSCs were expanded in peripheral blood of OA subjects relative to body mass index and in mice fed a high-fat diet (HFD) compared to mice fed a low-fat diet (LFD). In mice, monocytic MDSC (M-MDSC) was expanded in diet-induced obesity (DIO) with a further expansion after destabilization of the medial meniscus (DMM) surgery to induce post-traumatic OA (PTOA) (compared to sham-operated controls). M-MDSCs from DIO mice had a greater capacity to form osteoclasts in culture with increased subchondral bone osteoclast number. In humans, we observed an expansion of M-MDSCs in peripheral blood and synovial fluid of obese subjects compared to lean subjects with OA. CONCLUSION: These data suggest that MDSCs are reprogrammed in metabolic disease, with the potential to contribute towards OA progression and severity.

Centers for Disease Control and Prevention 2017 Guidelines for Prevention of Surgical Site Infections: Review and Relevant Recommendations.

PURPOSE OF REVIEW: The associated patient morbidity and resource-intensive nature of managing surgical site infections (SSI) has focused attention toward not only improving treatment protocols but also enhancing preventative measures. The purpose of this review was to summarize the relevant updated CDC guidelines for the prevention of SSI that were released in 2017. The CDC recommends the integration of the guidelines for improvement in quality metrics, reportable outcomes, and patient safety. RECENT FINDINGS: The updated guidelines include generalized recommendations for parenteral antimicrobial prophylaxis, non-parenteral antimicrobial prophylaxis, glycemic control, normothermia, oxygenation, and antiseptic prophylaxis. The arthroplasty section includes recommendations for blood transfusion, systemic immunosuppressive therapy, and antibiotics during drain use. There was low-quality evidence precluding recommendations for preoperative intra-articular corticosteroid injections, orthopedic surgical space suits, and biofilm management. The recommendations provided throughout this review, including more recent guidelines from other organizations such as the AAOS and ACR, should assist clinicians in developing and/or refining surgical site prevention protocols for their patients undergoing total joint arthroplasty procedures.

Polypropylene mesh augmentation for complete quadriceps rupture after total knee arthroplasty.

INTRODUCTION: Polypropylene mesh has previously been shown to be an effective treatment for failed patellar tendon repairs after total knee arthroplasty (TKA), but there have been few reports of this synthetic mesh used in complete quadriceps rupture after TKA. METHODS: We retrospectively reviewed seven consecutive cases in six patients with complete quadriceps tears after TKA who had their quadriceps tendon repaired with suture and polypropylene mesh augmentation. All but two patients had previously failed primary suture repair. Patient outcomes were evaluated using the Knee Society Score. Standardized anterior-posterior (AP), lateral and merchant radiographs were evaluated preoperatively and at final follow-up. RESULTS: Seven knees in six patients were evaluated with a mean follow-up of 34±10 (range 24 to 49months) months. There were only four clinical successes defined as an extensor lag less than 30°. Of the functioning knees at final follow-up (n=5) the overall extensor lag in this group did significantly improve from 50±13° to 20±15° (range 5 to 40°) (p=.01). Mean postoperative flexion at final follow-up was 115±8°. Mean Knee Society Score for function improved from 20±30 to 45±54 (p=.03) as did the mean Knee Society Score for pain (44±18 vs. 74±78, p=.02). DISCUSSION: Polypropylene mesh offered limited postoperative functional results when used as an augment to the multiply operated knee that sustains a complete quadriceps rupture after TKA, but did allow for significant improvement in postoperative pain outcomes. LEVEL OF EVIDENCE: IV.

Torsion deformity and joint loading for medial knee osteoarthritis.

PURPOSE: The consequences of lower limb torsion deformity on knee loading in knee osteoarthritis are poorly understood. The purpose of this study was to quantify the associations between the mechanical axis, tibial torsion and knee loading in subjects with medial knee OA and in controls. METHODS: Twenty-four subjects: end-staged medial knee osteoarthritis (OA) with apparent torsion deformity (TKO, n=6) and without torsion deformity (KOA, n=8) and controls (CON, n=10) were imaged using long standing lower extremity (LSLE) radiographs and computed tomography (CT). Medial knee loading was assessed using the internal knee varus moment determined by gait analysis. The LSLE mechanical axis, CT tibial torsion and the foot progression angle were used to predict medial knee loading. RESULTS: The TKOs had significantly greater mechanical axis varus and knee varus moment compared to KOAs and CONs. The regression model predicting medial knee loading using the mechanical axis (ß=0.898), tibial torsion (ß=0.264) and foot progression angle (ß=-0.369) showed a goodness of fit of 0.774. CONCLUSIONS: Medial knee loading was predicted by the mechanical axis and the foot progression angle. Future longitudinal studies are needed to assess the role of tibial intorsion during disease progression and following total knee replacement surgery.