Orthopedics

A Short Stem Solution: Through Small Portals

Adolph V. Lombardi Jr., MD; Keith R. Berend, MD; Joanne B. Adams, BFA

Abstract

While short stem design in total hip arthroplasty (THA) is not a new concept, interest has surged with the increasing popularity of less invasive techniques. Given the success of traditional stems, why consider short stems? Several reasons exist. If the goal of the tapered stem is to load preferentially proximally, achieve tight fit, and deliver stresses into proximal bone, do we need a stem at all? While long stems may prevent varus malalignment, varus malalignment of tapers does not impair results. Short stems are easier to insert, especially when using an anterior approach. Femoral preparation is accomplished with straightforward broaching without reamers. Short stems are bone conserving, violating less bone stock and providing more favorable conditions should revision be required. As with any novel device, longer follow-up is needed to fully assess shortened tapered stems. However, our early results in 640 primary THAs at up to 38 months are promising.

Usually 1 or 2 diameter sizes larger are required with the short vs standard length version of the same tapered design. Be aggressive with sizing, pushing to the largest possible. Use the broach like a rasp. Drive the component in valgus during insertion. Upon seating, do a trial reduction using the shortest available neck length. The component generally sits slightly prouder than the broach and may require additional effort to seat completely.

While the use of short stem designs in total hip arthroplasty (THA) is not a new concept,1 interest in such designs has surged recently with the increasing popularity of less invasive surgical techniques. Design styles can be categorized into 4 groups: those influenced by the Mayo Conservative stem (Zimmer, Warsaw, Indiana) introduced by Morrey1 in 1988, short and bulky but not neck sparing (eg, Proxima; DePuy, Warsaw, Indiana), neck-sparing curved designs (eg, CFP; Waldemar Link, Hamburg, Germany), and shortened tapered stems (eg, TaperLoc Microplasty; Biomet, Warsaw, Indiana).

Our practice has had extensive experience with a tapered titanium porous plasma-sprayed stem of standard length (Mallory-Head Porous; Biomet) in primary THA. We recently reported our results with 2000 primary THAs performed using this device from August 1984 through July 2001, noting 39 stem revisions at an average follow-up of 10 years yielding 98% survivorship with an endpoint of stem revision for any reason and 99% survivorship with stem revision for aseptic loosening.2 These results have been corroborated in several studies.3-7 Likewise, a number of studies report excellent results at intermediate and long-term follow-up with the TaperLoc stem, which is also a standard-length tapered titanium porous plasma-sprayed design.8-12 Given the success of these traditional stems, why should short stems be considered? Several reasons exist.

What is the optimal length of a tapered femoral component? A survey of tapered and short femoral prostheses currently available for primary THA reveals a wide variety of diameters and corresponding lengths (Table). If the goal of the tapered stem is to load preferentially proximally, why do we need a stem at all? Perhaps the only reason to use a tapered, long stem is to prevent varus. However, studies have shown that varus malalignment of a tapered stem does not affect results.3,13 In an effort to prevent distal off-loading, the TaperLoc stem is available with a reduced profile option. McLaughlin and Lee8-11 have reported excellent results using this reduced profile option in several published studies. Their results raise 2 questions: what function is the stem serving and do we need a long stem? The philosophy of a tapered design is to load the femur proximally, to achieve a tight fit, and to deliver the stresses into the proximal bone.

Table: Click to view larger chart.

Short stems…

Abstract

While short stem design in total hip arthroplasty (THA) is not a new concept, interest has surged with the increasing popularity of less invasive techniques. Given the success of traditional stems, why consider short stems? Several reasons exist. If the goal of the tapered stem is to load preferentially proximally, achieve tight fit, and deliver stresses into proximal bone, do we need a stem at all? While long stems may prevent varus malalignment, varus malalignment of tapers does not impair results. Short stems are easier to insert, especially when using an anterior approach. Femoral preparation is accomplished with straightforward broaching without reamers. Short stems are bone conserving, violating less bone stock and providing more favorable conditions should revision be required. As with any novel device, longer follow-up is needed to fully assess shortened tapered stems. However, our early results in 640 primary THAs at up to 38 months are promising.

Usually 1 or 2 diameter sizes larger are required with the short vs standard length version of the same tapered design. Be aggressive with sizing, pushing to the largest possible. Use the broach like a rasp. Drive the component in valgus during insertion. Upon seating, do a trial reduction using the shortest available neck length. The component generally sits slightly prouder than the broach and may require additional effort to seat completely.

Figure 1: The TaperLoc Microplasty femoral component
Figure 1: The TaperLoc Microplasty femoral component (Biomet) is a tapered, titanium, porous plasma-sprayed device available with either standard or lateralized offset and in 13 sizes, with diameters ranging from 5 to 25 mm and lengths ranging from 95 to 135 mm.

While the use of short stem designs in total hip arthroplasty (THA) is not a new concept,1 interest in such designs has surged recently with the increasing popularity of less invasive surgical techniques. Design styles can be categorized into 4 groups: those influenced by the Mayo Conservative stem (Zimmer, Warsaw, Indiana) introduced by Morrey1 in 1988, short and bulky but not neck sparing (eg, Proxima; DePuy, Warsaw, Indiana), neck-sparing curved designs (eg, CFP; Waldemar Link, Hamburg, Germany), and shortened tapered stems (eg, TaperLoc Microplasty; Biomet, Warsaw, Indiana).

Our practice has had extensive experience with a tapered titanium porous plasma-sprayed stem of standard length (Mallory-Head Porous; Biomet) in primary THA. We recently reported our results with 2000 primary THAs performed using this device from August 1984 through July 2001, noting 39 stem revisions at an average follow-up of 10 years yielding 98% survivorship with an endpoint of stem revision for any reason and 99% survivorship with stem revision for aseptic loosening.2 These results have been corroborated in several studies.3-7 Likewise, a number of studies report excellent results at intermediate and long-term follow-up with the TaperLoc stem, which is also a standard-length tapered titanium porous plasma-sprayed design.8-12 Given the success of these traditional stems, why should short stems be considered? Several reasons exist.

What is the optimal length of a tapered femoral component? A survey of tapered and short femoral prostheses currently available for primary THA reveals a wide variety of diameters and corresponding lengths (Table). If the goal of the tapered stem is to load preferentially proximally, why do we need a stem at all? Perhaps the only reason to use a tapered, long stem is to prevent varus. However, studies have shown that varus malalignment of a tapered stem does not affect results.3,13 In an effort to prevent distal off-loading, the TaperLoc stem is available with a reduced profile option. McLaughlin and Lee8-11 have reported excellent results using this reduced profile option in several published studies. Their results raise 2 questions: what function is the stem serving and do we need a long stem? The philosophy of a tapered design is to load the femur proximally, to achieve a tight fit, and to deliver the stresses into the proximal bone.

Table: Stem Diameters and Lengths for a Selection of Currently Marketed Designs

Table: Click to view larger chart.

Short stems are easier to insert, especially when using an anterior approach to the hip, such as the anterior supine intermuscular approach in which the proximal femur is elevated anteriorly from the wound during stem insertion. Femoral preparation can be accomplished with straightforward broaching of the canal, without the use of reamers. Short stems are bone conserving. They violate less femoral bone stock, providing more favorable conditions should a revision be required.

However, ease of insertion and conservation of bone matter little if not supported by clinical results. Thus, we reviewed our early experience with over 600 cases using short, tapered titanium, porous plasma spray-coated femoral components. From May 2003 through August 2008, 591 patients (640 hips) underwent primary THA by 2 surgeons (A.V.L., K.R.B.) at our institution using the TaperLoc Microplasty stem (Figure 1), with a lateralized offset option used in 388 (61%) of these THAs. A less invasive direct lateral approach was used in 363 (57%) THAs, a muscle-sparing anterior supine intermuscular approach was used in 251 (39%), and a standard direct lateral approach was used in 25 (4%). Forty-four percent (259) of patients were men, and osteoarthritis was the most common diagnosis, noted in 81% (519) of hips (Figure 2). Average age at time of surgery was 62.7 years (range, 27-91 years), and body mass index averaged 30.4 kg/m2 (range, 19-60 kg/m2).

Figure 2A: Severe joint space narrowing, sclerosis, osteophyte, and cyst formation Figure 2B: Cementless primary left THA with a 10 × 105-mm TaperLoc Microplasty stem Figure 2C: Well-fixed components in satisfactory position and alignment

Figure 2: Preoperative radiograph of the left hip of a 78-year-old woman who presented with severe pain and discomfort secondary to osteoarthritis shows severe joint space narrowing, sclerosis, osteophyte, and cyst formation (A). Radiograph at 6 weeks postoperatively shows treatment of cementless primary left THA with a 10 × 105-mm TaperLoc Microplasty stem and metal-on-highly crosslinked polyethylene articulation (B). Radiograph at 3 years postoperatively shows well-fixed components in satisfactory position and alignment. The patient has a Harris hip score of 97.5 (C).

Follow-up averaged 7.3 months (range, 1-38 months). Harris hip pain scores improved from an average of 13 preoperatively (0-44 possible) to 37 at most recent follow-up. Harris hip total scores improved from an average of 50 preoperatively (0-100 possible) to 80 at most recent follow-up. Six femoral components (0.9%) have been revised: 1 stem (standard direct lateral approach) was revised the same day because of perforation of the posterior femoral cortex during preparation, and 5 stems (1 standard direct lateral approach, 4 anterior supine intermuscular approach) have been revised for periprosthetic femoral fracture (Figure 3) at 0.6 to 5.0 months postoperatively. Two additional stem complications—1 periprosthetic fracture (anterior supine intermuscular approach) and 1 subsidence (standard direct lateral approach, Figure 4)—were treated conservatively.

Figure 3A: Severe joint space narrowing, sclerosis, osteophyte, and cyst formation Figure 3B: Cementless primary left THA with an 11 × 107.5-mm TaperLoc Microplasty lateralized stem Figure 3C: A periprosthetic femur fracture with large lateral butterfly fragment Figure 3D: Treatment of femoral component change to a 13 × 170-mm Mallory-Head Porous hydroxyapatite-coated stem

Figure 3: Preoperative radiograph of the left hip of a 53-year-old man who presented with severe pain and discomfort secondary to osteoarthritis shows severe joint space narrowing, sclerosis, osteophyte, and cyst formation (A). Immediate postoperative radiograph shows treatment of cementless primary left THA with an 11 × 107.5-mm TaperLoc Microplasty lateralized stem and metal-on-metal large head articulation (B). Radiograph at 1 month postoperatively reveals a periprosthetic femur fracture with large lateral butterfly fragment (C). Radiograph postoperative to revision reveals treatment of femoral component change to a 13 × 170-mm Mallory-Head Porous hydroxyapatite-coated stem augmented with strut allograft and cerclage cables (D).


Figure 4A: Severe joint space narrowing, sclerosis, osteophyte, and cyst formation Figure 4B: Treatment of cementless primary left THA with a 10 × 105-mm TaperLoc Microplasty lateralized stem Figure 4C: Subsidence of the femoral component Figure 4D: The patient has no pain and a Harris hip score of 88

Figure 4: Preoperative radiograph of the left hip of a 67-year-old woman who presented with severe pain and discomfort secondary to osteoarthritis shows severe joint space narrowing, sclerosis, osteophyte, and cyst formation (A). Immediate postoperative radiograph shows treatment of cementless primary left THA with a 10 × 105-mm TaperLoc Microplasty lateralized stem and metal-on-highly crosslinked polyethylene articulation (B). Radiograph at 6 weeks postoperatively reveals subsidence of the femoral component (C). Radiograph at 1 year postoperatively reveals well-fixed components with no further progression of subsidence. The patient has no pain and a Harris hip score of 88 (D).

We usually require 1 or 2 diameter sizes larger with short porous tapered stems vs the standard-length version of the same design. The surgeon should be aggressive with sizing, pushing to the largest size possible. Use the broach like a rasp. Drive the component in valgus during insertion. Upon seating the component, do a trial reduction using the shortest available neck length. The component will generally sit slightly prouder than the broach and may require additional effort to seat completely.

As with any novel device, longer follow-up will be required to fully assess the efficacy of shortened tapered stems. However, our early results in 640 primary THAs at up to 38 months are promising.

References

  1. Morrey BF. Short-stemmed uncemented femoral component for primary hip arthroplasty. Clin Orthop Relat Res. 1989; (249):169-175.
  2. Lombardi AV Jr, Berend KR, Mallory TH, Skeels MD, Adams JB. Survivorship of 2000 tapered titanium porous plasma-sprayed femoral components. Clin Orthop Relat Res. 2009; 467(1):146-154.
  3. Berend KR, Mallory TH, Lombardi AV Jr, Dodds KL, Adams JB. Tapered cementless femoral stem: difficult to place in varus but performs well in those rare cases. Orthopedics. 2007; 30(4):295-297.
  4. Ellison B, Berend KR, Lombardi AV Jr, Mallory TH. Tapered titanium porous plasma-sprayed femoral component in patients aged 40 years and younger. J Arthroplasty. 2006; 21(6 Suppl 2):32-37.
  5. Marshall AD, Mokris JG, Reitman RD, Dandar A, Mauerhan DR. Cementless titanium tapered-wedge femoral stem: 10- to 15-year follow-up. J Arthroplasty. 2004; 19(5):546-552.
  6. Reitman RD, Emerson R, Higgins L, Head W. Thirteen year results of total hip arthroplasty using a tapered titanium femoral component inserted without cement in patients with type C bone. J Arthroplasty. 2003; 18(7 Suppl 1):116-121.
  7. Park MS, Choi BW, Kim SJ, Park JH. Plasma spray-coated Ti femoral component for cementless total hip arthroplasty. J Arthroplasty. 2003; 18(5):626-630.
  8. McLaughlin JR, Lee KR. Total hip arthroplasty with an uncemented tapered femoral component. J Bone Joint Surg Am. 2008; 90(6):1290-1296.
  9. McLaughlin JR, Lee KR. The outcome of total hip replacement in obese and non-obese patients at 10- to 18-years. J Bone Joint Surg Br. 2006; 88(10):1286-1292.
  10. McLaughlin JR, Lee KR. Total hip arthroplasty in young patients. 8- to 13-year results using an uncemented stem. Clin Orthop Relat Res. 2000; (373):153-163.
  11. McLaughlin JR, Lee KR. Total hip arthroplasty with an uncemented femoral component. Excellent results at ten-year follow-up. J Bone Joint Surg Br. 1997; 79(6):900-907.
  12. Parvizi J, Keisu KS, Hozack WJ, Sharkey PF, Rothman RH. Primary total hip arthroplasty with an uncemented femoral component: a long-term study of the Taperloc stem. J Arthroplasty. 2004; 19(2):151-156.
  13. Khalily C, Lester DK. Results of a tapered cementless femoral stem implanted in varus. J Arthroplasty. 2002; 17(4):463-466.

Authors

Drs Lombardi and Berend and Ms Adams are from Joint Implant Surgeons, Inc, New Albany, and The Ohio State University and Mount Carmel Health System, Columbus, Ohio.

Dr Lombardi receives royalties from, is a paid consultant to, is a paid speaker for, and receives research or institutional support from Biomet and receives royalties from Innomed. Dr Berend receives royalties from, is a paid consultant to, and receives research or institutional support from Biomet; is a paid consultant to Salient Surgical and Synvasive; and owns stock or stock options in Angiotech. Ms Adams has no relevant financial relationships to disclose.

Presented at Current Concepts in Joint Replacement 2008 Winter Meeting; December 10-13, 2008; Orlando, Florida.

Correspondence should be addressed to: Adolph V. Lombardi Jr, MD, Joint Implant Surgeons, Inc, 7277 Smith’s Mill Rd, Ste 200, New Albany, OH 43054.

DOI: 10.3928/01477447-20090728-09

10.3928/01477447-20090728-09

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