Matthew S. Austin and Brian A. Klatt
DEFINITION
Total hip arthroplasty is the standard of care for symptomatic degenerative joint disease of the hip that is unresponsive to nonoperative treatment.
Cementless total hip arthroplasty has demonstrated excellent mid- to long-term results.
The acetabular component obtains initial fixation through a press-fit and has a surface that allows for in- or on-growth of bone.
The femoral component obtains intial fixation through a press-fit in either the metaphysis or diaphysis and has a surface that allows for in- or on-growth of bone. The metaphyseal-fit prosthesis may be either wedge-shaped or fit-and-fill.
ANATOMY
The acetabulum must be exposed so that the anterior and posterior walls, superior dome and rim, and teardrop are visualized.
The proximal femur must be exposed so that the periphery of the proximal femoral neck cut is visualized.
PATHOGENESIS
Degenerative joint disease of the hip is the endpoint of many hip disorders, including osteoarthritis, inflammatory arthritis, dysplasia, osteonecrosis, trauma, and sepsis.
NATURAL HISTORY
Degenerative joint disease of the hip often follows a variable symptomatic course. It is unknown why some patients progress more rapidly than others and why some patients are more symptomatic than others.
PATIENT HISTORY AND PHYSICAL FINDINGS
The history should be directed to determine whether the patient‘s pain is extrinsic or intrinsic.
The patient‘s pain may be extrinsic (eg, lumbar radiculopathy, intrapelvic pathology), and hip arthroplasty may fail to relieve the patient‘s pain completely, even in the face of severe degenerative changes of the hip.
Pain usually is located in the groin but may be located in the medial thigh, buttock, or the medial knee.
Range of motion (ROM) should be observed. Normal ROM of the hip is an arc of motion of 120 to 140 degrees of flexion–extension, 60 to 80 degrees of abduction–adduction, and external–internal rotation of 60 to 90 degrees. Loss of motion may be due to pain, contracture, or abnormal biomechanics.
Nonoperative treatment must be optimized before consideration is given to surgery.
Leg lengths should be measured and recorded preoperatively, and the patient should be counseled as to reasonable postoperative expectations.
Examinations to perform include:
Trendelenburg test. The test is positive if the contralateral hip drops inferiorly; this may indicate that the hip abductors are compromised.
Hip flexion–internal rotation. The test is positive if the patient‘s pain is recreated. Pain that is not recreated with this examination may be from an extrinsic source.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Plain radiographs, including anteroposterior (AP) views of the pelvis and AP and true lateral views of the hip, should be obtained to evaluate the anatomy, assess for deformity, and devise an adequate plan preoperatively (FIG 1).
DIFFERENTIAL DIAGNOSIS
Lumbar radiculopathy
Spinal stenosis
Sacroiliac degenerative joint disease
Intra-abdominal pathology
Intrapelvic pathology
Neuropathy
Meralgia paresthetica
Complex regional pain syndrome
Vascular claudication
Primary bone tumors
Metastasis
Infection
FIG 1 • AP radiograph of the hip demonstrates advanced degenerative changes of osteophytes and joint space obliteration.
NONOPERATIVE MANAGEMENT
Acetaminophen
Nonsteroidal anti-inflammatory drugs
Glucosamine
Chondroitin sulfate
Physical therapy
SURGICAL MANAGEMENT
The primary indication for cementless total hip arthroplasty is painful, severe degenerative joint disease of the hip that has been nonresponsive to appropriate nonoperative treatment modalities.
Preoperative Planning
Preoperative planning for routine cementless primary total hip arthroplasty can be accomplished with plain radiographs at standard magnifications.
Standard templates are available for the components, and many are available for digital templating as well.
The acetabular component is placed so that the inferomedial edge of the cup is at the radiographic “teardrop.” The inclination is 35 to 45 degrees, and the cup should contact the superolateral rim of the acetabulum.
The femoral component is placed so that the center of rotation is at the level of the greater trochanter. The femoral offset should be reproduced. However, the femur must be internally rotated 10 to 15 degrees on the radiograph to bring the femoral neck into the plane of the radiograph. Externally rotated femora will appear to be in coxa valga.
Proximal-fit femoral prostheses are designed to obtain fit in the metadiaphyseal region.
Diaphyseal-fit femoral prostheses are designed to obtain fit in the diaphysis.
Positioning
The patient is positioned according to surgeon preference and in accordance with the surgical approach.
The hip should be draped in such a fashion as to allow a wide surgical exposure should an extensile approach be required in the event of a complication.
The pelvis must be stabilized in a secure fashion to avoid pelvic tilt, which may affect the surgeon‘s perception of the acetabular position.
Approach
The hip can be exposed for primary routine arthroplasty via a variety of approaches:
Anterior
Anterolateral
Direct lateral
Posterior
Two-incision
Small-incision variants of these approaches
TECHNIQUES
ACETABULAR EXPOSURE
The approach to the hip is chosen according to the surgeon's preference. The approach illustrated here is the direct lateral (modified Hardinge) approach in the supine position.
Retractors are placed in the anterior, superior, and inferior positions, thereby exposing the entire periphery of the acetabulum (TECH FIG 1).
The labrum is resected.
The soft tissue in the cotyloid fossa is removed, allowing exposure of the medial wall and teardrop.
TECH FIG 1 • Acetabular exposure. A. Supine position for modified Hardinge approach. B. Completed acetabular exposure. The medial wall and native acetabular anatomy are easily visualized. C. Labrum is resected. D.Osteotome removes osteophytes from cotyloid fossa. E. Currette removes remaining tissue to expose teardrop.
ACETABULAR PREPARATION
Before reaming, the entire periphery of the acetabulum, medial wall, and teardrop must be directly visualized (TECH FIG 2).
The initial reaming must be done with moderate pressure until the quality of bone is assessed.
The goal of the initial reaming is to medialize the reamer fully. The cotyloid fossa should be eliminated without penetrating the medial wall.
Reaming then proceeds sequentially. The goal is to recreate the center of rotation by placing the inferomedial aspect of the socket at the level of the teardrop with the component inclined at 35 to 45 degrees and with 10 to 20 degrees of anteversion and with good initial fixation obtained through a press-fit.
The templated size should be used as a guide; intraoperatively, an increase or decrease in cup diameter may be found to be appropriate.
Failure to recognize the need for a different cup diameter may lead to iatrogenic fracture or a failure to achieve initial fixation.
The bony bed should be bleeding but not devoid of sclerotic bone.
The pelvis must remain in a stable position to avoid malpositioning of the acetabular component.
TECH FIG 2 • Acetabular preparation. A. Initial reaming to medialize acetabulum fully. B. Reaming completed to medial wall. C. Reaming proceeds sequentially at 35 to 45 degrees of abduction and 10 to 20 degrees of anteversion.
ACETABULAR COMPONENT IMPLANTATION
The position of the pelvis is reassessed. Any tilt is corrected.
The trial component or reamer is used to assess bone coverage of the component and position (TECH FIG 3). If the trial or reamer is not seated properly, then further reaming may be necessary. If deemed appropriate, implantation of the actual component may proceed.
The actual implant should be 1 to 2 mm larger than the last reamer. The surgeon must know the actual diameter of the implant, taking into account any rim or coating.
TECH FIG 3 • Acetabular component implantation. A. Final reamer is used to assess component position, bony coverage, and seating. B. Acetabular component is implanted. C. Central hole is used to verify that the cup is fully seated. D. Actual liner is inserted into the cup.
Implants that are larger than the size of the last reamer by 4 mm or more are associated with risk of fracture.
The acetabular component is then implanted, with care taken to medialize the implant. The inferomedial aspect of the cup should be at the level of the teardrop in 35 to 45 degrees of abduction and 10 to 20 degrees of anteversion.
A trial liner or the actual liner is then inserted.
FEMORAL EXPOSURE
The femur is exposed by elevating it out of the wound with a retractor (Bennett or double-footed).
The periphery of the femur is exposed with another retractor (TECH FIG 4).
The soft tissues must be protected so that iatrogenic damage by reamers or broaches is avoided.
TECH FIG 4 • Femoral exposure. The femur is elevated and exposed with two double-footed retractors to allow atraumatic broaching.
FEMORAL PREPARATION (PROXIMAL-FIT PROSTHESIS)
The femur is prepared as delineated by the surgical protocol for each prosthesis (TECH FIG 5). The surgeon should be familiar with the prosthesis and all of the available options and idiosyncrasies.
The proximal-fit prosthesis usually requires a starter reamer, which is used as a canal-finder. In addition, the reamer should be lateralized to avoid broaching and subsequent varus positioning of the implant.
The femur then is broached sequentially, with care taken to lateralize the broach. Broaching is complete when the broach ceases to advance, the pitch of impaction increases, and good cortical contact is obtained.
TECH FIG 5 • Femoral preparation. A. Rongeur is used to clear tissues and lateral cortical bone. B. Curette used to find canal. C,D. Canal is reamed to open canal, and care is taken to lateralize. E. Broaching proceeds. F,G.Final broach is seated.
Improper broaching can lead to fracture, malposition, or undersizing.
The component should be anteverted 10 to 15 degrees.
The greater trochanter can be used as a reference to recreate the center of rotation.
It may be necessary to adjust the neck cut to allow for further seating of the prosthesis.
The templated size should be used as a guide, and an increase or decrease in stem size intraoperatively may be appropriate.
Failure to recognize the need for a different size may lead to iatrogenic fracture or failure to achieve initial fixation.
A standard or varus neck is selected based on the soft tissue tension and the patient's anatomy.
FEMORAL COMPONENT IMPLANTATION (PROXIMAL-FIT PROSTHESIS)
The implant chosen usually matches the size of the last broach.
The proximal-fit femoral component is inserted, with care taken to avoid varus positioning (TECH FIG 6).
The implant is impacted until it ceases to advance, the pitch of impaction increases, there is good cortical contact, and the implant has reached the level of the last broach.
TECH FIG 6 • Femoral component implantation (proximal-fit prosthesis). A. Canal appearance before implantation. B,C. Component is introduced in proper orientation until resistance is met. D. Component fully seated.
SOFT TISSUE TENSION/LEG-LENGTH DETERMINATION
The hip is trial reduced and assessed for soft tissue tension, stability, ROM, impingement, and leg length.
The soft tissue tension should allow for no more than 1 to 2 mm of toggle (TECH FIG 7).
The hip should be stable within the patient's physiologic ROM. If instability exists, the position of the components must be reassessed.
The ROM should be physiologic for the patient.
TECH FIG 7 • Soft tissue tension and leg-length determination. A. Hip is reduced. Soft tissue tension is evaluated. B. Abduction/external rotation. C. Adduction/internal rotation. D.Flexion/adduction/internal rotation.
Impingement must be assessed and rectified with removal of any remaining osteophytes.
Increased offset may aid in decreasing impingement.
Proper component position must be verified to exclude positioning as a source of impingement.
The patient's leg length is assessed either directly through palpation of the heels or malleoli or indirectly through the use of a pin placed in the ilium and a marker placed on the femur.
One must be careful to position the limb accurately to avoid inducing error during the measurement process.
CLOSURE
The wound is thoroughly irrigated.
Drains are placed at the discretion of the surgeon.
The capsule is closed meticulously, especially if a posterior approach has been used.
The soft tissues are closed with absorbable suture.
The skin is closed according to surgeon preference.
POSTOPERATIVE CARE
Weight bearing after cementless total hip arthroplasty is controversial. Some surgeons routinely restrict weight bearing for 6 weeks, whereas others allow weight bearing as tolerated.
Hip precautions are prescribed according to the approach.
Posterior approaches avoid flexion, internal rotation, and adduction, whereas anterior approaches avoid extension, external rotation, and adduction.
The hip precautions are discontinued at 6 weeks.
Some surgeons who perform the anterior approach have discontinued the use of traditional hip precautions.20
The patient ambulates with the aid of crutches or a walker for several weeks, then progresses to use of a cane. Generally, the cane is discontinued at 6 weeks.
OUTCOMES
The survivorship of cementless total hip arthroplasty components generally has been excellent, although isolated reports of high failure rates exist for certain designs, which have subsequently been abandoned. Most modern, uncemented acetabular and femoral components have reported survivorship of 95% to 100% at midto long-term follow-up.1–19,21–23
Overall survival of cementless acetabular components has ranged from 83% to 99.1% at 8.5 to 16.3 years of followup.1,3,6,7,10–12,15,21,23
The reported survivorship of cementless femoral components has ranged from 82% to 100% at 6.6 to 17.5 years of follow-up.1,2,4,5,8,9,12–14,16–18,19,22
The main limitation to long-term clinical success has been wear and subsequent osteolysis.
COMPLICATIONS
Iatrogenic fracture
Stress shielding of proximal bone
Blood loss
Infection
Neurovascular injury
Anesthetic and medical complications
Loosening
Osteolysis
REFERENCES
1. Archibeck MJ, Berger RA, Jacobs JJ, et al. Second-generation cementless total hip arthroplasty: Eight to eleven-year results. J Bone Joint Surg Am 2001;83A:1666–1673.
2. Bojescul JA, Xenos JS, Callaghan JJ, et al. Results of porous-coated anatomic total hip arthroplasty without cement at fifteen years: A concise follow-up of a previous report. J Bone Joint Surg Am 2003;85:1079–1083.
3. Callaghan JJ, Savory CG, O‘Rourke MR, et al. Are all cementless acetabular components created equal? J Arthroplasty 2004;19(4, Suppl 1):95–98.
4. Capello WN, D‘Antonio JA, Feinberg JR, et al. Ten-year results with hydroxyapatite-coated total hip femoral components in patients less than fifty years old: a concise follow-up of a previous report. J Bone Joint Surg Am 2003;85:885–889.
5. Della Valle CJ, Paprosky WG. The middle-aged patient with hip arthritis: the case for extensively coated stems. Clin Orthop Relat Res 2002;(405):101–107.
6. Della Valle CJ, Berger RA, Shott S, et al. Primary total hip arthroplasty with a porous-coated acetabular component. A concise followup of a previous report. J Bone Joint Surg Am 2004;86:1217–1222.
7. Duffy GP, Prpa B, Rowland CM, et al. Primary uncemented HarrisGalante acetabular components in patients 50 years old or younger: results at 10 to 12 years. Clin Orthop Relat Res 2004;427:157–161.
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18. Parvizi J, Sharkey PF, Hozack WJ, et al. Prospective matched-pair analysis of hydroxyapatite-coated and uncoated femoral stems in total hip arthroplasty: a concise follow-up of a previous report. J Bone Joint Surg Am 2004;86A:783–786.
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20. Peak. EL, Parvizi J, Ciminiello M, et al. The role of patient restrictions in reducing the prevalence of early dislocation following total hip arthroplasty. A randomized, prospective study. J Bone Joint Surg Am 2005;87A:247–253.
21. Robertson A, Lavalette D, Morgan S, et al. The hydroxyapatitecoated JRI-furlong hip. Outcome in patients under the age of 55 years. J Bone Joint Surg Br. 2005;87B:12–15.
22. Teloken MA, Bissett G, Hozack WJ, et al. Ten to fifteen-year followup after total hip arthroplasty with a tapered cobalt-chromium femoral component (trilock) inserted without cement. J Bone Joint Surg Am 2002;84A:2140–2144.
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