By: 20 June 2014
Patient-specific instruments for the knee: A lasting trend or fad?

GlobalData, a market intelligence leader delivering the latest industry reports in the orthopaedic market, questions the latest technological improvements for knee replacements.

Knee replacement is one of the most popular orthopaedic surgeries today, and every year millions of these surgeries are performed around the world. In Europe, the expanding patient population for orthopaedic surgical treatments, the widespread appreciation of the clinical efficacy of knee replacement, and the steady domestic supply of orthopaedic devices have all contributed to a stable increase in the procedure volume in the past decades. According to GlobalData, the market revenue for knee replacement in the five major EU countries (France, Germany, Italy, Spain and the UK) was approximately $1.2 billion in 2013. There is never a lack of innovation in this multi-billion dollar market, and the most recent wave of enthusiasm is about patient-specific instruments (PSIs).

To surgeons, PSIs may allow for reliable alignment and fewer outliers compared with conventional total knee replacement (TKR). Computer software facilitates preoperative planning and predicts intraoperative bone resections, component sizes and alignment. The custom guides manufactured from these data potentially alleviate the need for multiple trays of trial implants, further increasing operative efficiency. Moreover, these instruments provide a way to achieve consistent implant positioning in TKR, especially for patients with unusual bony anatomy.

The major driver behind this trend is that such pre-made patient-specific systems provide orthopaedic companies with visibility into demand. Surgeons typically upload magnetic resonance imaging (MRI) or computed tomography (CT) scans of a patient’s joint anatomy to manufacturers and order these personalised instruments three to four weeks in advance of the surgery. Manufacturers then work with surgeons to organise preoperative planning and fabricate the custom instruments. Through this process, manufacturers gain insight into the most common bone deformities and the most desirable types of implants, so that they can realise more operational efficiency in production control and inventory optimisation. Moreover, they may achieve the long-term profitability derived from establishing a sustained relationship with implant sales within the hospital.

The industry’s estimate for the current adoption rate of PSIs for TKR is approximately 20%. Although PSIs are available from nearly all major orthopaedic companies, and despite increasing usage, questions remain regarding the down side of this technology in today’s cost-conscious healthcare setting. First of all, the jury is still out on whether these systems can provide the clinical benefits that were once anticipated. Additional data are also needed before the widespread use of these instruments can be recommended in all types of knee replacements. Some key concerns include the possibility of an alignment error or component size mismatch between the bone resections suggested by these instruments and those that are desired intraoperatively, which would cause the surgeon to make changes during surgery. Secondly, PSIs may increase the wait time to surgery, as it often takes a couple of weeks for surgeons to receive the fabricated instruments from the companies after approval of the preoperative plan. The extra waiting time involved in using these systems has come into question. Moreover, the cost-effectiveness of PSIs in joint replacement also remains unclear. The use of a PSI requires an additional MRI/CT scan. When the scan costs are added to the cost of manufacturing the instruments, TKR surgery with a PSI can cost about £500–£1,000 more than with conventional instruments. Even if the actual clinical advantages of PSIs outweigh their extra cost, insurers have cold feet in terms of providing reimbursement for them.

In April 2013, Stryker’s PSI product for TKR, the ShapeMatch, received a Food and Drug Administration (FDA) Class I recall due to a software defect that resulted in wider cutting ranges. Up to now, there has been no update regarding the ShapeMatch’s new regulatory approval. While companies continue to push the concept of these individualised instruments in an effort to offset the decreased margins of implant sales, they may also want to pay closer attention to the resistance to their adoption. As increasing numbers of hospitals implement austerity measures on high-volume hip and knee surgeries, cost-effectiveness will take the centre stage in surgeons’ uptake of newly-launched products. This raises the question of whether PSI for knee replacement is a real technological improvement or a fleeting commercial gimmick. Only time will tell.