What Are the Facts and Fiction of Minimally Invasive Hip and Knee Arthroplasty Surgery?

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Chapter 85 What Are the Facts and Fiction of Minimally Invasive Hip and Knee Arthroplasty Surgery?

Although minimally invasive surgical (MIS) techniques such as laparoscopic cholecystectomy and arthro-scopic anterior cruciate ligament reconstruction have gained widespread acceptance in the surgical community, reduced invasiveness in total joint replacement has stirred much controversy and debate. The concept of minimizing iatrogenic trauma has always been a fundamental surgical principle. However, it is only recently that the concept of small-incision surgery and minimal musculotendinous disturbance has come to the forefront in the total hip and total knee arthroplasty (THA and TKA) literature, the lay press, and commercial advertising.

There are several key characteristics of what is generally considered MIS joint replacement including reduced skin incision length, mobile windows of exposure, reduced muscle and tendon damage, avoidance of extreme maneuvers such as patellar eversion, and utilization of low-profile instrumentation. Any discussion of this topic must distinguish between those techniques that involve surgical approaches through smaller skin incisions and lessened muscle dissection from those procedures that describe truly novel and potentially technically challenging approaches to the hip and knee. In addition, it is important to recognize that any MIS joint replacement protocol also incorporates specialized preoperative and postoperative patient education, anesthesia routines, as well as nursing and rehabilitation programs.

Advocates for MIS joint replacement proclaim the benefits of less blood loss, less postoperative pain, reduced length of hospital stay, more rapid recovery of function, and better cosmesis without increased risk for complication or diminished duration of implant survivorship.111 However, other investigators have failed to find significant benefit from MIS joint replacement and have encountered steep and difficult learning curves.10,1218 Some investigators have discovered concerning rates of serious complications such as implant malposition, intraoperative fracture, skin complications, and prolonged operative durations.1824 These data combined with the well-documented and highly favorable long-term results of traditional-incision joint replacement have resulted in some vocal opposition to the placement of excessive emphasis on incision length.2527 Some authors have questioned the ethics of the broad application of such techniques without proven benefit, as well as the role that direct-to-consumer advertising and commercial interests have played before thorough study.2830

The purpose of this chapter is to review the available evidence in the literature that is capable of directing potential incorporation of novel MIS techniques into the already successful practice regimens of hip and knee arthroplasty, which have been developed over more than three decades. Techniques that involve smaller and modified implant plant components such as unicompartmental knee arthroplasty or resurfacing of the hip are not considered here. Although the overwhelming majority of data on this topic is derived from retrospective cohort studies and case–control series, there is a modest amount of Level I and II evidence available to draw some conclusions and make practice recommendations (Tables 85-1 and 85-2).

TABLE 85-2 Summary of Recommendations

RECOMMENDATIONS LEVEL OF EVIDENCE/GRADE OF RECOMMENDATION
A
B
A
B

OPTIONS

Hip

In MIS hip surgery, the dominant approaches have been modifications of standard anterior, posterior, and lateral surgical exposures, as well as a combined anterior and posterior approach commonly called the “two-incision” technique. This has led to the development of surgical instrument systems that are smaller and of lower profile, but the actual implants themselves have not changed in any significant way. The posterior technique of mini-incision THA has been described by authors such as Chimento and coworkers.31 This approach involves an incision of 6 to 10 cm in length without disruption of the gluteus maximus tendon or the quadratus femoris muscle. Berger1 has described an anterolateral approach that transects less gluteus medius and minimus through an 8- to 10-cm incision. Toms and Duncan32 have published a description of a single incision intermuscular anterolateral approach that they claim has advantages of standard lateral patient positioning, simple conversion to an extensile approach, no need for fluoroscopy, and a short learning curve for surgeons.

Among the most controversial novel hip approaches has been the two-incision method written about extensively by Berger.33 It has been claimed that this technique is completely intermuscular and “avoids the transection of any muscle or tendon.”1 The two-incision technique utilizes an anterior, Smith–Peterson interval for the acetabular exposure, and a posterior incision between the abductors and the external rotators for stem insertion. The described technique requires intraoperative fluoroscopic imaging.

Knee

Three modifications of standard techniques have gained wider utilization in the knee, as well as one novel approach, which has much less general acceptance. All four techniques have in common abandonment of the formerly common practice of patellar eversion and tibiofemoral dislocation for exposure purposes.34 They also make use of the concept of “mobile windows” of exposure that utilize varying degrees of flexion and extension throughout the procedure to allow visualization of the femur or the tibia, but not both simultaneously.

Scuderi and coworkers35 use a 10- to 14-cm skin incision and a medial parapatellar arthrotomy that differs from a standard approach in that the quadriceps tendon is incised only 2 to 4 cm above the superior pole of the patella. The subvastus approach that Hofmann36 described has been modified to make it less invasive. A shortened anterior, midline skin incision is made, and a medial parapatellar arthrotomy follows. The attachment of the vastus medialis obliquus (VMO) muscle to the quadriceps tendon and upper patellar pole is left intact. The VMO muscle belly is then retracted so that limited dissection can occur posterior to the muscle belly, anterior to the intermuscular septum. Synovial release of the suprapatellar pouch is required, and the patella is subluxed laterally.35 The standard midvastus approach that Engh and colleagues37 described has been modified to lessen its damage to the VMO. A shortened midline anterior skin incision is utilized. A medial arthrotomy is made and the incision is extended proximally into the full thickness of the vastus medialis, in-line with its muscle fibers for a length or 4 to 5 cm starting at the superior-medial pole of the patella. The patella is then lateralized but not dislocated.35

The technique that deviates to the greatest degree from traditional techniques and has gained the least general acceptance has been described by Tria and Coon38 and is commonly referred to as the “quadriceps-sparing” technique. This technique uses a curved medial incision from the superior pole of the patella to the tibial joint line. An arthrotomy is then made in line with the skin incision. Bony cuts are made using instruments and guides that fixate and cut from the medial side of the knee rather than the standard anterior location. The quadriceps tendon and VMO are theoretically left completely intact.

EVIDENCE

Hip

Because of the earlier interest and development of MIS applications to THA, the hip literature is more robust than that of the knee. The earliest work in this realm consisted almost exclusively of case series and expert opinions. Despite the absence of high-quality research, many orthopedic surgeons have determined the degree to which they would incorporate MIS concepts into their practice based on the recommendation of opinion leaders, as well as their own personal experience. Fortunately, sufficient time has now elapsed to allow several Level I and II studies to be published.

In 2005, Ogonda and coauthors13 reported on a prospective, randomized, controlled trial of 219 patients with 219 THAs studied over a period of 6 months. Patients were blinded to length of incision, and all surgery was performed by a single surgeon using a posterior approach. Of critical importance, and one of the strengths of this study, was the fact that the treating surgeon had already become adept at MIS techniques by previously performing 300 short-incision THAs. In the standard-incision group, the subcutaneous tissues and fascia lata were divided in line with the skin incision, which was 16 cm long. In the MIS group, only the proximal 1 cm of the fascia lata was incised. The distal fibers of the gluteus maximus were split by blunt dissection, and the short external rotators were detached close to their insertion into the greater trochanter. These authors found no difference in component position and wound complications, and no evidence of lessened inflammation in the MIS group based on C-reactive protein measurements at 48 hours after surgery. Most remarkably, there were no differences in function immediately after surgery or at 6 weeks, based on Harris hip scores, Oxford hip scores, WOMAC Index of Osteoarthritis and SF-12 general health questionnaire. There was also no benefit for the MIS group in terms of length of hospital stay. These authors conclude that MIS incision surgery performed by an experienced surgeon through a posterior approach is safe but of no benefit in the early postoperative phase. They also caution that more investigation is required to determine the appropriateness of this technique for lower volume and less experienced surgeons.13

Chimento and investigators5

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