Introduction

Tourniquet use in total knee arthroplasty (TKA) remains controversial and few reports exist using contemporary pain protocols and tranexamic acid (TXA). This study aimed to examine whether a modern TKA protocol without a tourniquet results in less blood loss, patient-reported pain, and opioid consumption compared to TKAs with a tourniquet.

Until recently, research has failed to show a difference between posterior-stabilised (PS) and cruciate-retaining (CR) designs in total knee arthroplasty (TKA). This classic debate has been given pause over the past decade due to futile efforts to prove one design superior over the other. Recently, anterior-lipped and more conforming CR bearings have emerged to substitute for the PCL, if absent, damaged or resected, and obviate the need for the archaic cam-post mechanism of a traditional PS design. Advantages of avoiding a PS TKA include decreasing the risk of femoral condylar fracture that may occur via the box cut, as well as decreasing operative time by removing that step in the procedure. Avoiding a post-cam mechanism also removes the articulation that is a source of wear, post deformation, breakage, or dislocation. Patella clunk is also associated solely with PS designs.

Modern anterior lipped inserts in PCL-deficient TKAs have demonstrated similar functional outcomes compared to PS knees. A prospective randomised controlled trial of 28 patients undergoing bilateral TKAs had a PS bearing in one knee and a contralateral CS insert with the PCL excised and reported no functional outcome difference at 5-year follow up. Scott and co-authors compared 56 PS TKAs to 55 TKAs with anterior-lipped inserts in a randomised, prospective study and found no functional outcome differences at minimum two-year follow up, with tourniquet times significantly longer in the PS group. In a recent report, 43 anterior-lipped compared to 39 matched PS TKAs had equivalent function scores at minimum 1-year follow-up. Ultra-congruent bearings provide inherent stability in TKA and two studies have reported identical functional outcomes compared to PS TKAs. Finally, there is now recent registry data that demonstrates a significant decrease in long-term survivorship in PS TKAs with a 45% higher risk of revision compared to minimally stabilised bearings in TKA.

Equivalent functional outcomes in multiple studies comparing CR-type bearings and PS TKAs, combined with the potential deleterious outcomes associated with PS designs and increased risk of revision and decreased long-term survivorship, preclude the need for PS TKA designs in the modern healthcare environment. Hence, PS TKA designs are truly “vestigial organs”, and should be relegated to historical interest.

Until recently, research has failed to show a difference between posterior-stabilised (PS) and cruciate-retaining (CR) designs in total knee arthroplasty (TKA). This classic debate has been given pause over the past decade due to futile efforts to prove one design superior over the other. Recently, anterior-lipped and more conforming CR bearings have emerged to substitute for the PCL, if absent, damaged or resected, and obviate the need for the archaic cam-post mechanism of a traditional PS design. Advantages of avoiding a PS TKA include decreasing the risk of femoral condylar fracture that may occur via the box cut, as well as decreasing operative time by removing that step in the procedure. Avoiding a post-cam mechanism also removes the articulation that is a source of wear, post deformation, breakage, or dislocation. Patella clunk is also associated solely with PS designs.

Modern anterior lipped inserts in PCL-deficient TKAs (CS) have demonstrated similar functional outcomes compared to PS knees. A prospective randomised controlled trial of 28 patients undergoing bilateral TKAs had a PS bearing in one knee and a contralateral CS insert with the PCL excised and reported no functional outcome difference at 5-year follow up. Scott and co-authors compared 56 PS TKAs to 55 TKAs with anterior-lipped inserts in a randomised, prospective study and found no functional outcome differences at minimum two-year follow up with tourniquet times significantly longer in the PS group. In a recent report, 43 anterior-lipped compared to 39 matched PS TKAs had equivalent function scores at minimum 1-year follow-up. Ultra-congruent bearings provide inherent stability in TKA and two studies have reported identical functional outcomes compared to PS TKAs.

Equivalent functional outcomes in multiple studies comparing CR-type bearings and PS TKAs, combined with the potential deleterious outcomes associated with PS designs, preclude the need for PS TKA designs in the modern health care environment. Hence, PS TKA designs are truly “vestigial organs”, and should be relegated to historical interest.

Introduction

Tourniquet use in total knee arthroplasty (TKA) remains controversial and few reports exist using contemporary pain protocols and tranexamic acid (TXA). This study aimed to examine whether a modern TKA protocol without a tourniquet results in less blood loss, patient-reported pain, and opioid consumption compared to TKAs with a tourniquet.

Until recently, research has failed to show a difference between posterior-stabilised (PS) and cruciate-retaining (CR) designs in total knee arthroplasty (TKA). This classic debate has been given pause over the past decade due to futile efforts to prove one design superior over the other. Recently, anterior-lipped and more conforming CR bearings have emerged to substitute for the PCL, if absent, damaged or resected, and obviate the need for the archaic cam-post mechanism of a traditional PS design. Advantages of avoiding a PS TKA include decreasing the risk of femoral condylar fracture that may occur via the box cut, as well as decreasing operative time by removing that step in the procedure. Avoiding a post-cam mechanism also removes the articulation that is a source of wear, post deformation, breakage, or dislocation. Patella clunk is also associated solely with PS designs.

Anterior lipped inserts in PCL-deficient TKAs have demonstrated similar functional outcomes compared to PS knees. A prospective randomised controlled trial of 28 patients undergoing bilateral TKAs had a PS bearing in one knee and a contralateral CS insert with the PCL excised and reported no functional outcome difference at 5-year follow up. Scott and co-authors compared 56 PS TKAs to 55 TKAs with anterior-lipped inserts in a randomised, prospective study and found no functional outcome differences at minimum two-year follow up, with tourniquet times significantly longer in the PS group. In a recent report, 43 anterior-lipped compared to 39 matched PS TKAs had equivalent function scores at minimum 1-year follow-up. Ultra-congruent bearings provide inherent stability in TKA and two studies have reported identical functional outcomes compared to PS TKAs.

Equivalent functional outcomes in multiple studies comparing CR-type bearings and PS TKAs, combined with the potential deleterious outcomes associated with PS designs, preclude the need for PS TKA designs in the modern healthcare environment. Hence, PS TKA designs are truly “vestigial organs” and should be relegated to historical interest.

Cementless fixation in TKA has been inconsistently adopted since its early use but is increasing due to a number of factors, predominantly related to a demand for improved survivorship in younger patients. Modern biomaterials have demonstrated optimal bone ingrowth and have also contributed to a renewed confidence by surgeons to utilise cementless fixation in TKA. With a modern design and appropriate surgical technique, optimal mechanical stability of new designs have been demonstrated and can build upon the excellent long-term outcomes that have rivaled traditional cemented TKA. Paramount to obtaining successful long-term osseointegration and clinical survivorship with cementless fixation is an awareness of the past failure mechanisms to improve implant modern implant design, and should also guide meticulous surgical technique.

A robust implant design with optimal surgical technique is critical to success when employing cementless fixation in TKA. The tried and true principles of sufficient mechanical stability to minimise micromotion of an osteoconductive implant surface with intimate contact against viable bone are essential to allow osseointegration and long-term survivorship. The surgical techniques and tips for “getting it right” include: 1.) Meticulous planar cuts - Prevention of saw blade deviation (particularly anterior femoral cortex and sclerotic medial tibial plateau), Appropriate tolerances in cutting guides (particularly 4-in-1 femoral cutting guide), Appropriate interference fit for tibial keel/stem, patella planar cut, Perfect planar cut on tibial surface confirmed with “4-corner test”. 2.) Implantation of components to maximise mechanical stability - Intimate implant contact with bone (minimizing gaps), Consider bone slurry to minimise gaps, Prevention of femoral component flexion with impaction, Ensure parallel position of tibial baseplate with tibial cut surface during impaction, Peripheral fixation on tibial baseplate, either screws or pegs, to provide supplemental fixation and stability in titanium tray designs.

Peri-articular injections (PAI) have become an important component in many multimodal pain protocols after total knee arthroplasty (TKA). Liposomal bupivacaine has emerged as a highly marketed and touted ingredient for PAI. However, the true efficacy of this material, particularly compared with less expensive PAI “cocktails” such as traditional bupivacaine or ropivacaine, has not been proven to date.

Ropivacaine is considered a long-active local analgesic and in combination with epinephrine, ketorolac and clonidine has been shown to be a very effective PAI in a multimodal pain program. Liposomal bupivacaine has been similarly touted as a long-acting PAI. Initial reports provided support for liposomal bupivacaine PAI's providing similar pain relief as epidurals or femoral nerve blocks. The authors of these studies tout comparable pain control with decreased length of stay attributable to avoiding the side effects of epidurals and regional blocks. However, the ultimate clinical issue relates to how liposomal bupivacaine PAI's compares to traditional PAI cocktail ingredients such as bupivacaine and ropivacaine, which also avoid deleterious effects of regional analgesia, and at a much cheaper price point. Fortunately the highest quality research to date, which includes randomised prospective trials and retrospective controlled cohort studies, have reported consistent results. In a retrospective cohort study comparing a traditional ropivacaine and epinephrine versus liposomal bupivacaine PAI demonstrated no difference between the two groups in inpatient pain scores when used in a comprehensive multimodal pain control program. Further, two prospective randomised trials reported no difference in liposomal bupivacaine PAI compared to a traditional PAI of either bupivacaine or ropivacaine, epinephrine, ketorolac and clonidine. Finally, there have been some authors who contend the efficacy of liposomal bupivacaine PAI's is entirely dependent on a meticulous injection technique, however, comparative studies against traditional PAI ingredients with this recommended technique do not exist.

In summary, the existing data supports that liposomal bupivacaine is an effective PAI that can be used to provide comparable pain relief to that achieved by regional blocks. However, liposomal bupivacaine has not been shown to provide superior pain relief when compared to traditional ropivacaine or bupivacaine PAI's in multimodal pain protocols after TKA. Further, liposomal bupivacaine is prohibitively priced at approximately six times that of ropivacaine-based PAI cocktails. Therefore, the “game changer” is likely the implementation of peri-articular injections as an essential component of multimodal pain control programs and NOT liposomal bupivacaine.

Cementless femoral components have an excellent track record that includes efficient implantation and long-term survival, thus are the predominant stem utilised in North America. Femoral component stability and resistance to subsidence are critical for osseointegration and clinical success. Implant design, surgical technique, anatomic fit, and patient characteristics, such as bone quality, can all effect initial implant stability and resistance to subsidence. Variability in stem shape and in the anatomy of the proximal femoral metaphysis has been implicated in the failure of some stem designs. Biologic fixation obtained with osseointegration of cementless implants may improve implant longevity in young, active, and obese patients. Lack of intimate fit can lead to clinical complications such as subsidence, aseptic loosening, and peri-prosthetic fracture. Currently, there are several stem designs, all of which aim to achieve maximal femoral stability and minimal subsidence and include: Fit and Fill / Double Taper Proximally Porous Coated Stems; Parallel Sided Taper Wedge or “Blade” Stems; Wagner Style Conical Shape Splined Titanium Stems; Tapered Rectangular Cross-Section Zweymuller Stem; Fully-Porous Coated Stems; Modular Proximal Sleeve Fluted Stem; Anatomic Proximally Porous Coated Stems.

The majority of patients with relatively straightforward anatomy can be treated with any of the aforementioned femoral implant types. However, more complicated femoral anatomy frequently requires a particular implant type to maximise stability and promote osseointegration. Stems with femoral deformity in the meta-diaphyseal region may require a shorter stem in order to avoid an osteotomy. Distorted femoral anatomy typically seen in childhood diseases, such as dysplasia, may require a modular proximal sleeve tapered fluted stem or Wagner style cone stem to impart optimal stem anteversion separate from the native femoral neck version. The most severe forms of dysplasia may require a shortening osteotomy and subsequent distal fixation and neck version flexibility, which can be addressed with a modular proximal sleeve fluted or fully porous coated stem. A stovepipe or osteoporotic femur may require a stem that engages more distally such as a conical splined tapered stem, a fully porous coated stem or even a cemented stem to achieve adequate stability. Finally, obese patients are a particular challenge and emerging data suggests that a morphologically based parallel-sided taper wedge stems may confer greater stability and resistance to subsidence in these patients. Ultimately, an appropriate selection algorithm will facilitate an appropriate match of the patient morphology with femoral implant geometry that facilitates stable fixation and osseointegration.

Recent issues related to trunionosis have created a new paradigm in choosing femoral head material in total hip arthroplasty. While many consider highly-crosslinked polyethylene (XLPE) to be the gold standard currently in acetabular liner bearing surface, the debate remains whether metal or ceramic heads are best paired with XLPE.

Wear characteristics are similar within an order of magnitude when comparing cobalt chrome femoral heads with ceramic when used in combination with XLPE. Therefore, discernable differences between the two femoral head materials with respect to outcomes would be the result of other biomechanical factors. Notably the fretting and corrosion of metal heads at the modular taper of femoral components is a serious concern and represents a significant deterrent when considering this material. The fretting corrosion that occurs with metal femoral heads has recently been well documented in multiple reports, and can be associated with adverse local tissue reactions necessitating revision hip arthroplasty. Frictional torque has recently been implicated in taper corrosion at modular junctions. In a recent simulated in vivo study, large diameter CoCr femoral heads were associated with increased frictional torque compared to smaller metal heads, supporting recent taper corrosion retrieval studies. In one recent series, a 1.1% incidence of head-neck taper corrosion with a metal head was reported and the authors recommended use of ceramic femoral heads. The notable downside of ceramic femoral heads is the implant cost and potential for fracture. However, the incidence of femoral head fracture with the newer mixed delta ceramic heads is exceptionally low and infrequent (rate 1.7 per 100,000). Furthermore, the incidence of taper corrosion is negligible with ceramic heads, making it the bearing couple of choice among many surgeons in combination with XLPE.

There are a multitude of choices and implant varieties for primary total knee arthroplasty (TKA). TKA implant systems differ in a number of design characteristics intended to either improve performance through optimizing kinematic function (such as the medial pivot, mobile bearing, gender-specific or high-flexion designs) or by increasing the durability of the TKA by minimizing long-term failure modes, such as wear and osteolysis with highly cross-linked polyethylene.

Further adding to the complexity of choice, is the re-emergence of cementless fixation in response to improve longevity in the progressively younger TKA patient population. The patella creates additional decision-making in TKA, as while most surgeons in the US resurface the patella, there are some who routinely do not which is a much more commonly accepted practice outside of the US. Finally, metal hypersensitivity is a controversial, yet unavoidable issue, which forces the consideration of “nickel-free” or ceramic-coated implants. Unfortunately, there is paucity of outcome data to support one implant choice over another, which is problematic in the modern arena of value-based cost reductions in healthcare.

Further confounding the issue is the inability of current outcome measures to accurately assess the differences in performance of the various TKA designs. This talk will provide the latest evidence particular to the major TKA component choices as they relate to patient pathology.

There is a renewed interest in unicompartmental knee arthroplasty. The present report describes the minimum ten-year results associated with a – unicompartmental knee arthroplasty design that is in current use.

Sixty-two consecutive unicompartmental knee arthroplasties that were performed with cemented modular Miller-Galante implants in 51 patients were studied prospectively both clinically and radiographically. All patients had isolated unicompartmental disease without patellofemoral symptoms. No patient was lost to follow-up. Thirteen patients (13 knees) died after less than 10 years of follow-up, leaving 38 patients (49 knees) with a minimum of 10 years of follow-up. The average duration of follow-up was 12 years.

The mean Hospital for Special Surgery knee score improved from 55 points preoperatively to 92 points at the time of the final follow-up. Thirty-nine knees (80%) had an excellent result, six (12%) had a good result, and four (8%) had a fair result. At the time of final follow-up, 39 knees (80%) had flexion to at least 120 degrees. Two patients (two knees) with well-fixed components underwent revision to total knee arthroplasty, at seven and 11 years, because of progression of patello-femoral arthritis. At the time of the final follow-up, no component was loose radiographically and there was no evidence of peri-prosthetic osteolysis. Radiographic evidence of progressive loss of joint space was observed in the opposite compartment of nine knees (18%) and in the patello-femoral space of seven knees (14%). Kaplan-Meier analysis revealed a survival rate of 98.0% +/−2.0% at ten years and of 95.7% +/− 4.3% at 13 years, with revision or radiographic loosening as the end point. The survival rate was 100% at 13 years with aseptic loosening as the end point.

After a minimum duration of follow-up of 10 years, this cemented modular uni-compartmental knee design was associated with excellent clinical and radiographic results. Although the 10 year survival rate was excellent, radiographic signs of progression of osteoarthritis in the other compartments continued at a slow rate. With appropriate indications and technique, this uni-compartmental knee design can yield excellent results into the beginning of the second decade of use.