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.¹^–¹¹ However, other investigators have failed to find significant benefit from MIS joint replacement and have encountered steep and difficult learning curves.^10,¹²^–¹⁸ Some investigators have discovered concerning rates of serious complications such as implant malposition, intraoperative fracture, skin complications, and prolonged operative durations.¹⁸^–²⁴ 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.²⁵^–²⁷ 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.²⁸^–³⁰

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 85-1 Summary of Level I and II Evidence

TABLE 85-2 Summary of Recommendations

RECOMMENDATIONS	LEVEL OF EVIDENCE/GRADE OF RECOMMENDATION
1. Short incision approaches to the hip utilizing less invasive modifications of traditional posterior, lateral, and anterior approaches are a viable option in nonobese patients without prior hip surgery or major alterations to normal anatomy (such as protrusion or developmental dysplasia of the hip).	A
2. Minimally invasive hip approaches utilizing novel surgical approach (two-incision approach) are not recommended because of lack of evidence of any benefit and unacceptable complication rates.	B
3. Short-incision approaches to the knee utilizing less invasive modifications of traditional medial parapa-tellar, subvastus, or midvastus approaches are a viable option in nonobese patients without prior knee surgery or major alterations to normal anatomy.	A
4. Minimally invasive knee approaches utilizing novel surgical approach (quadriceps-sparing approach) is not recommended because of lack of evidence of clinical benefit and concerns about technical difficulty.	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 coworkers ³⁵ 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 Coon ³⁸ 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.