3D-printed Patient-specific Guides for Hip Arthroplasty.
TL;DR: Early results indicate consistent accurate positioning of implants with the use of PSI in hip arthroplasty but with added costs and uncertain effect on clinical outcomes.
Abstract: Surgeons and engineers constantly search for methods to improve the surgical positioning of implants used for joint arthroplasty. Rapid prototyping is being used to develop patient-specific instrumentation (PSI) and has already been successfully translated into large-scale clinical use for knee arthroplasty. PSI has been used in shoulder arthroplasty; however, it is not yet known whether PSI provides improved accuracy and outcomes compared with conventional methods in either shoulder arthroplasty or knee arthroplasty. In the hip, PSI has been limited to the positioning of custom-manufactured implants and a small number of surgeons testing the emerging solutions from different manufacturers. Early results indicate consistent accurate positioning of implants with the use of PSI in hip arthroplasty but with added costs and uncertain effect on clinical outcomes.
Summary (3 min read)
- The clinical function of a hip ar- throplasty depends on surgical, implant, and patient factors.
- The surgeon can then plan prosthesis ori- entation and position in relation to a chosen standard frame of reference and execute the plan using simple intra- operative patient-specific guides.
- Here, the authors present the currently commercially available guides and summarize the relevant literature regarding PSI for hip arthroplasty in order to provide an overview of PSI and describe the evidence regarding its use in clinical practice.
- Rapid prototyping was initially de- veloped in the mid 1980s for the production of toys and household machinery and has been used for a wide variety of medical and nonmedical purposes since that time.
- 12 PSI has evolved out of this and has been taken up in numerous fields of surgery.
Clinical Application in Hip Arthroplasty
- PSI is being used in hip arthroplasty to improve the accuracy of acetabular and femoral component position- ing.22-24 Acetabular guidance systems aim to optimize the cup size, implant medialization, anteversion, and incli- nation.
- Four commercial systems are currently available internationally .
- CT provides well-defined bony anat- omy with low levels of artifact; however, it has limitations in demonstrating soft tissue.
- It is as yet uncertain which is the optimal imag- ing modality for creation of PSI in total hip replacement and both are currently available depending on the commercial system chosen (Table 1).
- The frames of reference and target positioning/orientation of the implants can be tailored to the surgeon’s preference.
Does Patient-specific Instrumentation Improve the Accuracy of Cup Orientation?
- Buller et al29 undertook a dry bone simulation study, with seven sur- geons performing THA performed with standard instrumentation, fol- lowed by PSI-guided THA.
- In a prospective randomized con- trolled trial, Small et al32 compared 18 patients undergoing THA with conventional instrumentation and 18 patients undergoing THA with PSI.
- Results demonstrated a statistically significant difference in version of the acetabu- lar component between standard instrumentation and PSI (P = 0.018; mean difference from planned versus actual anteversion of 26.9 6 8.9 for standard instrumentation and 20.2 6 6.9 for PSI cases).
- A posterolateral surgical approach was used for each patient, and the PSI laser guidance system was used for the accurate placement of the acetabular implants.
- CT scans were used for preoperative planning.
Does the Use of Patient- specific Instrumentation Affect the Duration of Surgery?
- Hananouchi et al33 reported a mean surgical time of 106.1 minutes with PSI, compared with 116.3 minutes with standard instrumentation.
- In the PSI group, the mean time to use the surgical guide was 3.6 minutes.
- Ito et al34 used PSI for femoral component insertion and demonstrated a mean surgical time of 111 minutes.
- Small et al32 demonstrated a mean surgical time of 95 minutes for the PSI group versus 88 minutes for the standard instrumentation group; this trend was not found to be statistically significant.
Is Patient-specific Instrumentation Useful in Cases With Massive Bone Defects and Abnormal Anatomy?
- Substantial deformity and insufficient bone structure or quality are contra- indications for the use of currently available PSI guides for hip arthro- plasty.
- The dynamic modeling used preoperatively with PSI requires nor- mal anatomy and sites of rigid attachment for guiding instruments intraoperatively.
- Further develop- ments in the design of these guides may result in the ability to use these systems in patients with more severe deformity.
Does the Use of Patient- Specific Instrumentation Have Any Other Intraoperative Effects?
- Hananouchi et al33 demonstrated a mean blood loss of 655.9 mL for PSI versus 683.9 mL for standard instrumentation; this difference was not statistically significant, also known as Blood Loss.
- Ito et al34 reported a mean estimated blood loss of 356 mL using PSI for the femoral component.
- Small et al32 demon- strated mean estimated blood loss of 200 mL in the PSI group compared with 150 mL in the traditional in- strumented group; this trend was not found to be statistically significant.
- Spencer-Gardner et al27 reported one complication in a series of 100 patients in whom PSI was used for cup placement—a fractured ceramic liner due to incomplete seating requiring revision liner exchange, also known as Complications.
- In a randomized controlled trial of 18 PSI versus 18 standard instrumentation cases, Small et al32 demonstrated no com- plications in the PSI group and one complication in the standard instru- mentation group (anterior dislocation).
- PSI hip guides have been shown to improve the accuracy of implant positioning and may have a role to play in reconstructing complex anat- omy, particularly in revision surgery.
- More clinical outcomes data are required to convince the surgeon that the benefits of PSI in terms of accuracy are worth the challenges of the learning curve involved and the increased costs.
- Walch G, Vezeridis PS, Boileau P, Deransart P, Chaoui J: Three-dimensional planning and use of patient-specific guides improve glenoid component position: J Shoulder Elbow Surg 2015; 24:302-309. 20.
- Stegman J, Casstevens C, Kelley T, Nistor V: Patient-specific guides for total hip arthroplasty: A paired acetabular and femoral implantation approach.
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...With the advent of 3D printing and related technologies, future instrumentation and implants will be personalized to the individual characteristics of the patient [171,172]....
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Q1. What have the authors contributed in "3d-printed patient-specific guides for hip arthroplasty" ?
Patientspecific instrumentation ( PSI ) has been used to guide the positioning of components during hip arthroplasty this paper.