Figure 10 - uploaded by Timothy McTighe
Content may be subject to copyright.
Hip Resurfacing Arthroplasty and “Mid-Head” Resurfacing Arthroplasty (Birmingham System, Smith and Nephew)
Source publication
Advanced arthritis of the hip joint can lead to profound changes in quality of life. Debilitating
pain, stiffness, and altered gait biomechanics all affect the ability to stay mobile and maintain
gainful employment; these concerns are magnified in younger patients with hip disease. While
symptomatic hip arthritis typically affects older patients, t...
Similar publications
Oxinium is an alternative bearing surface designed to emulate the superior wear and scratch properties of ceramic femoral heads in total hip arthroplasty while minimizing the risk for brittle fracturing. However, recent studies have indicated that hip dislocation following total hip arthroplasty may be a risk factor for catastrophic failure of the...
Hip replacement is a surgical procedure in which the hip joint is replaced by a prosthetic implant. Hip replacement surgery can be performed as a total replacement or a hemi (half) replacement. Such joint replacement orthopaedic surgery is generally conducted to relieve arthritis pain or in some hip fractures. A total hip replacement (total hip art...
Articulating components should minimise the generation of wear particles in order to optimize long-term survival of the prosthesis.
A good understanding of tribological properties helps the orthopaedic surgeon to choose the most suitable bearing for each individual patient.
Conventional and highly cross-linked polyethylene articulating either with...
Citations
... Using neck-preserving implants leads to reduction of both torsional and bending moments inserted on the stem/bone interface. 16 This reduction may decrease micromotion and failure of osseointegration. 10 It has been shown that NPS stem implants may be more likely to recreate the three-dimensional anatomy of the proximal femur 13 and thus also facilitate achievement of physiologic reconstruction of the hip center which in turn may improve the outcome of THA. ...
Femoral neck-preserving short- (NPS) stem implants for total hip arthroplasty (THA) bear several advantages over longer-stem implants, such as native hip structure preservation and improved physiological loading. However, there still is a gap of knowledge regarding the potential benefits of a short-stem design over conventional neck-sacrificing stems in regards to patient-reported outcomes (PROs). The authors investigated the differences in PROs between a neck-sacrificing stem design and NPS stem design arthroplasty. They hypothesized that PROs of NPS stem THA would be higher in the medium-term in comparison to the neck-sacrificing implant system. Neck-sacrificing implant patients (n = 90, age 57 ± 7.9 years) and a matched (body mass index [BMI], age) cohort group of NPS implant patients (n = 105, age 55.2 ± 9.9 years) reported both preoperative and postoperative hip disability and osteoarthritis outcome scores (HOOS). Average follow-up was 413 ± 207 days (neck sacrificing implant) and 454 ± 226 days (NPS implant). The authors applied multivariate analysis of variance (MANOVA) and Mann–Whitney tests for statistical analyses. Significance levels were Holm–Bonferroni adjusted for multiple comparisons. HOOS Subscores increased significantly after surgery independent of implant type (p < 0.001). There was a significant time by surgery interaction (p = 0.02). Follow-up HOOS subscores were significantly higher in the NPS implant group: symptoms (p < 0.001), pain (p < 0.001), activities of daily living (ADL; p = 0.011), sports and recreation (p = 0.011), and quality of life (QOL; p = 0.007). While long-term studies are required for further investigation, evidence from the current study suggests that NPS implants may provide a significant benefit to primary THA patients, which could be due to physiological loading advantages or retention of bone tissue.
Introduction
The DAA for THA has evolved into a safe and effective hip replacement technique that
offers many distinct clinical advantages.1 The disadvantages of DAA stem from
difficulties with femoral exposure and implantation and the need for learning a new
technique.2
Short femoral stem designs have emerged to facilitate femoral preparation and
implantation through the DAA. These stems can decrease the amount of femoral release
required for exposure. The curved, neck-sparing arthroplasty (NSA) stems can be
introduced medially, reducing the need to remove bone close to the greater trochanter.
This reduces the risk of proximal femur fracture and decreases the need for capsular
releases to achieve adequate femoral exposure (Figure 33-1). In addition, short femoral
stems allow for shorter incisions, less bone loss, increased ease of future
removal, and compatibility with all canal configurations.3,4
Short femoral stems have been used overseas for at least a decade longer than in the
United States.5-7 Early designs were modifications of current standard cementless stems
in which the diaphyseal portion was truncated. Early data suggested that stable, durable
fixation and excellent clinical outcomes can be achieved with these
modifications.3,8,9 Today, a variety of short-stem implants are available with an array of
design features, with limited information to guide the surgeon in terms of design
rationale, fixation features, surgical technique, and clinical outcomes.9,10
Since 2012, the Joint Implant Surgery and Research Foundation (JISRF) has advocated
a femoral stem classification system.10-12 This system is organized by primary
stabilization contact regions, as follows:
1. Head stabilized
a. Hip resurfacing
b. Mid-head stem
2. Neck stabilized
a. Short curved neck stabilized stem
b. Short lateral flare engaging neck stabilized stem
c. Neck plugs
2
3. Short metaphyseal stabilized
a. Short taper stems
b. Bulky or “fit-and-fill” stems
4. Conventional metaphyseal/diaphyseal stabilized (not considered a short stem)
In the previous scheme, implants in groups 2a and 3a are of interest to DAA THA.
Key Learning Points
● Specialized retractor systems can facilitate exposure and decrease the need for
personnel during director anterior approach (DAA) total hip arthroplasty (THA).
● Data support the use of the Phantom Minimally Invasive Surgery (MIS) Anterior
Hip Retractor system (TeDan Surgical Innovations, Inc. [TSI] United States Patent #
8,808,176 B2) both for experienced surgeons who can expedite the operation and for
novice surgeons who may be able to shorten the learning curve. Since the introduction
of DAA to the United States, many studies have demonstrated the validity of DAA
THA using a standard operating table.
1-4 Downsides to the technique include the need for multiple assistants, as well as
difficulties with femoral exposure, which may result in femoral perforation/fracture,
soft tissue trauma, and component malposition, creating a distinct and potentially
lengthy learning curve.5-7
5
The Phantom MIS technique entails a specialized retractor system that enhances
exposure during DAA THA and allows fluoroscopic visualization and prepping of the
contralateral limb in the field. This self-retaining system employs the use of adjustable
surgical arms with attachable retractors. The operation can be done on a standard
operating table with minimal additional personnel. The ability to prepare both lower
extremities in the surgical field allows for direct clinical limb length comparison, a
more familiar feel of reduction, soft tissue tension, and complete, dynamic joint range
of motion. The manual femoral elevation system exposes the femur well, while
providing controlled forces and feel of tension, which may decrease soft tissue trauma,
nerve stretch, and fracture risk.
Thus the system provides both excellent acetabular exposure and femoral exposure,
while allowing the use of fluoroscopy for both acetabular and femoral preparation.
Additional advantages include attachable, small LED lighting and high-definition
camera systems to illuminate and film the surgical field.
Total hip arthroplasty (THA) is one of the most effective orthopedic procedures, providing consistently high success rates across all population segments as measured by pain relief, improved function, and patient satisfaction (1–4). While symptomatic hip arthritis typically affects older patients, this segment of the patient population is more active than it has ever been. Many septuagenarians and octogenarians maintain a vigorous lifestyle and will experience a greater longevity. In addition, THA has become an option for a growing subset of active patients aged 30 to 60 years who are affected by coxarthrosis and who were previously thought of as “too young for a hip replacement” (5,6). This cohort of patients is internet savvy and thus well informed about the treatment options for their disability. As a group, they are demanding earlier surgical intervention to restore the quality of their lifestyle (7,8).
Over the past 10 years, the orthopedic community has witnessed an increased interest in more conservative surgical techniques for hip arthroplasty (9–12). During this time, second-generation hip resurfacing and minimally invasive surgery (MIS) enjoyed extensive marketing attention. After a decade of this renewed interest, both of these methods for THA have met with serious concerns (13–15). As hip resurfacing numbers decline, both patients and surgeons are looking for other potentially successful conservative treatments to THA. This search has recently focused surgeon interest toward short-stem designs (Fig. 64.1A,B).
Most reports on short stems have appeared as oral presentations and posters at continuing medical education (CME) meetings (16,17). The international experience precedes that of the United States by at least a decade (18–20). The initial response in the U.S. market was simply to modify certain current standard cementless stems by truncating the diaphyseal portion of the stem. Short-and midterm follow-up studies of a number of these stems suggest that stable, durable fixation and excellent clinical outcomes can be achieved (8–10,13,15,21). Today, a variety of short-stem implants are available with very little clarification of design rationale, fixation features, surgical technique, and clinical outcomes. Virtually every major implant company now offers a “short stem,” and now there are a plethora of different designs. It is important to note, however, that not all short stems achieve initial fixation at the same bone interface region. Furthermore, surgical techniques vary greatly, and postoperative radiographic interpretation of short-stem position and fixation needs to be carefully scrutinized (14,22). Finally, the surgeon who is new to short-stem technology is often unaware of the surgical preparation difference for a short metaphyseal style stem versus a neck-persevering style stem. For example, a number of neck-preserving stems prefer rasping the medial femoral curve versus impaction broaching. This has a back-and-forth technique that cuts and shapes the bone to the rasp and final implant. The broach impacts cancellous bone into a dense material and can increase hoop tension, resulting in distal fractures in some cases.
The purpose of this chapter is to review past, present, and potential future developments of short femoral stems and to present a classification system that can offer guidance when reporting on the many different stem variations.
An influx of short stems have been introduced into the global market with no standards as to design, fixation, and surgical technique making clinical outcome data confusing when trying to compare results. A femoral stem classification system (JISRF) has been developed defining stems by stabilization contact region. Short Curved Neck Stabilized Stems (2a) have a significant biomechanical advantage as compared to stem designs that utilize a standard neck resection technique. 2a stems have a reduction of 40% in bending and torsional moments along with a 35% reduction in tensile stress. Data indicates that short curved neck stabilized stems (2a) can be successfully implanted through all hip approaches and the JISRF stem classification provides guidelines as to design, technique and outcomes.
