Experts' consensus on minimally invasive surgery for total joint arthroplasty

Introduction

Minimally invasive surgery for total joint arthroplasty (MIS‐TJA) has been the focus of joint surgery in recent years. With the continuous advancement of minimally invasive techniques, they hold strong appeal for orthopaedic surgeons both in theory and in practice. However, the understanding, application and implementation of these techniques are still controversial. The Chinese Medical Association, the Chinese Orthopaedic Association, and the editorial board of the Chinese Journal of Orthopaedics sponsored a senior expert seminar on MIS‐TJA on 12 August 2006. Almost all members of the joint surgery groups and senior experts were invited to discuss the concepts, approaches, advantages and disadvantages, indications, contraindications, and technical features of MIS‐TJA. Finally, a consensus was reached on expert advice regarding the basis for performing MIS‐TJA.

Minimally invasive surgery for total hip arthroplasty

Overview

In this document, MIS‐THA refers specifically to primary total hip arthroplasty (THA), including cemented and cementless THA.

The length of the incision with the MIS‐THA technique is less than 10–12 cm ¹ , and is characterized by partial or completely sparing of muscles and tendon tissues.

Minimally invasive surgery may reduce surgical trauma, and promote faster recovery. However, MIS and “mini‐incisions” should not be pursued blindly at the cost of clinical outcomes. That is, it should be ensured that MIS is safe and effective.

Surgical approaches

• 1 Posterolateral approach

  More than just a small skin incision is required for the conventional posterolateral approach, which still cuts off the short external rotators ² , ³ .

• 2 Lateral approach

  The gluteus medius muscle is divided at the junction of the anterior one‐third and posterior two‐thirds. An L‐shaped incision in the gluteus minimus tendon and an anterior capsulectomy are then performed ⁴ .

• 3 Anterior approach

  This approach follows the intermuscular space between the tensor fascia latae and sartorius muscles. The lateral femoral circumflex artery and vein are ligated. This provides excellent anterior exposure of the hip joint capsule. Either a two‐incision (Berger) ⁵ , or a single‐incision anterior approach (Siguier) ⁶ , can be used.

• 4 Anterolateral approach

  This approach is through the intermuscular space between the gluteus medius and tensor fasciae latae muscles. The Orthopädische Chirurgie München (OCM) approach is a completely muscle‐sparing approach to the hip joint ⁷ .

Advantages and disadvantages

• 1 Advantages

  MIS‐THA has developed to decrease blood loss and minimize muscle damage. Postoperative advantages include a more stable joint, faster functional recovery, less postoperative pain, a shorter hospital stay, and more rapid rehabilitation ⁸ , ⁹ , ¹⁰ . In addition, the MIS approach is associated with a smaller skin incision and surgical scar ¹¹ , reduced medical and ancillary care costs, and a more rapid recovery. MIS‐THA achieves good outcomes during short‐term follow‐up, but more studies are needed to evaluate its long‐term outcomes ⁵ , ⁷ , ⁸ , ¹⁰ .

• 2 Disadvantages

  Due to the reduced exposure and limited visibility associated with MIS, surgeons should be familiar with the local anatomy, MIS techniques, and the special instruments required. The MIS technique is not suitable for complex and revision joint arthroplasty. To master MIS techniques, surgeons need rigorous training with a steep learning curve. Surgeons without formal training or new surgeons may worsen tissue damage and increase operative complications ⁹ , ¹⁰ , ¹² , ¹³ .

Indications and contraindications

Minimally invasive surgery for total joint arthroplasty is not appropriate for all patients, and not all surgeons can master the required techniques. Only observation of the appropriate indications and a sufficiently experienced surgeon result in good patient outcomes.

• 1 Indications
  • a. Body mass index (BMI), the weight (in kg)/height² (in m²), should be ≤30. In the early stages of their learning curve, surgeons should perform MIS only on patients with a BMI of less than 30, particularly when the patient has muscular legs.
  • b. The femoral head should be dislocated intraoperatively to ensure that cutting of the femoral neck to remove the femoral head is performed under direct vision.
  • c. There is no need for reconstruction of the acetabulum.

    In addition, the use of a cementless prosthesis is recommended in as many cases as possible. Considering the limited operative field, less experienced surgeons would find it difficult to remove excessive bone cement quickly enough. During the early stages of their learning curve, surgeons should perform MIS on female patients.

• 2 Relative contraindications
  • a. Obesity, BMI >30.
  • b. Joint ankylosis and osteophyte of the medial femoral head.
  • c. A need to perform auxiliary operations such as bone transplantation, removal of internal fixation plates, and so on.
  • d. Severe osteoporosis.
  • e. Severe hip dysplasia (Crowe types III and IV) and acetabular protrusion.
  • f. Revision surgery.
• 3 Absolute contraindications
  • a. Bone erosion in the proximal femur, such as in patients with tumors.
  • b. The proximal femur cannot be exposed outside the incision because of an intertrochanteric fracture.
  • c. Previous hip surgery.

Surgical features of MIS‐THA

MIS‐THA differs from conventional THA. The following are tips and tricks for operative techniques and perioperative management.

• 1 Surgical instruments

  To facilitate performance of MIS‐THA with its limited surgical visual fields, conventional instruments for the placement of hip prosthesis must be modified.

  • a. Special traction operating table.

    For anterior and anterolateral MIS‐THA, femoral exposure is more difficult. Thus, special assistance should be obtained by using a traction operating table. The patient should be placed in the supine position on a Judet traction bed for single‐incision MIS‐THA; this helps with performance of traction and rotation of the affected limb. For MIS‐THA through the OCM approach, the patient should be placed in the lateral recumbent position on a Jupiter traction bed and the lower limb hyperextended intraoperatively and positioned vertically.

  • b. Modified Hohmann retractor.

    A long‐handled, highly curved Hohmann retractor is helpful for performing small incisions and minimizing soft tissue damage. Moreover, installation of special illumination devices is recommended to improve intraoperative lighting.

  • c. Angled reamer.

    We recommend the use of a specially designed angled reamer and hemispherical acetabular reamer (half‐reamer).

  • d. Modular prosthesis.

    We recommend the use of modular cementless prosthesis, which will help to streamline operations within the limited space available and avoid the need to remove bone cement.

  • e. Computer‐assisted orthopaedic surgery (CAOS).

    CAOS helps trace the relative position and spatial orientation of surgical instruments intraoperatively, allowing surgeons to perform osteotomies, acetabular bone reaming, and placement of prosthetic implants accurately under indirect vision.

• 2 Surgical technique
  • a. Incision minimization and location accuracy.

    With more experience, the incision can be further reduced and the focus can be on minimal dissection under the skin. If necessary, a surgeon should not hesitate to extend the incision. We should not blindly utilize small incisions at the cost of clinical outcomes. Considering the difficulty of converting minimally invasive approaches into conventional incisions in some cases, the location of the incision should be carefully considered. Otherwise, the procedure will be more difficult to perform.

  • b. “Moving window” technique.

    The “Moving window” technique refers to exposing the operative region systematically. When the operative region is exposed on one side, the retractor should be relaxed on the contralateral side, and vice versa. This leads not only to better exposure of the operative region, but also to less soft tissue damage and skin tears.

  • c. Do not complete the osteotomy in one step.

    Due to the mini‐incision, removal of the femoral head cannot be performed after hip dislocation. Osteotomy of the femoral neck should be completed in two steps. Before removing the remnants of the femoral head, the wedge‐shaped bone should first be removed.

  • d. Deep soft tissue repair around the hip.

    The muscles and joint capsule should be repaired to improve postoperative hip stability. With the posterolateral approach, the short external rotators should be sutured. With the anterolateral approach, which partially disconnects the gluteal muscle, the ends of the gluteus medius muscle should be sutured to the bone tunnel of the greater trochanter. With the anterior and anterio‐lateral approaches, which do not disconnect any muscles, the anterior capsule should be sutured.

• 3 Perioperative education and rehabilitation

  Patients should be told preoperatively about the length of hospitality stay and surgical time. Postoperatively, patients should undergo ambulation training on the floor as early as possible, unless they have comorbidities which contraindicate this. There are no clear limitations on postoperative body position. Patients should be encouraged to undergo early rehabilitation and discharge. The minimal damage to the joint capsule, intraoperative repair of the posterior joint capsule and surrounding soft tissues, and the application of navigation systems increase joint stability. Therefore, emphasis on body position for preventing dislocation of the hip is no longer necessary.

Complications

Although MIS‐THA has advantages over conventional THA, it does have postoperative complications related to the small incision and limited exposure, including acetabular cup malposition, excessive anteversion with the anterior approach, excessive retroversion with the posterior approach, nerve injury; hematoma; wound problems, periprosthetic fractures, and muscle damage ¹³ . The surgeon should have extensive experience with conventional THA before attempting MIS‐THA. The incision length can be gradually reduced with increased experience. Although MIS‐THA has deservedly become a popular surgical technique, it is not a technique for all patients and all surgeons.

Minimally invasive surgery for total knee arthroplasty

Overview

The length of incision recommended for minimally invasive surgery for total knee arthroplasty (MIS‐TKA) is 10–14 cm. The quadriceps‐sparing (QS) approach is typical ¹⁴ , ¹⁵ . It does not damage the quadriceps mechanism, destroy the suprapatellar bursa, nor evert the patella. It is clear that the mini‐incision technique is not equal to MIS.

Surgical approaches

• 1 Mini‐medial parapatellar approach ¹⁶

  The incision into the quadriceps tendon should extend 2–4 cm above the superior pole of the patella. The arthrotomy should be of a sufficient length to sublux the patella laterally over the lateral femoral condyle with eversion.

• 2 Mini‐midvastus approach 17, 18

  The incision should extend from 1 cm above the superior pole of the patella to the proximal half of the tibial tubercle on its medial side. A medial arthrotomy should extend from the superior pole of the patella to the level of the tibial tubercle. The vastus medialis obliquus muscle should be identified and an oblique split made in it along the line of its fibers at the level of the superior pole of the patella. This muscle split is generally 2–3 cm in length.

• 3 Mini‐subvastus approach ¹⁴

  The incision should start at the superior pole of the patella and end at the top of the tibial tubercle. The arthrotomy should be performed along the inferior edge of the vastus medialis obliquus muscle down to the midpole of the patella. At the midpole of the patella, the arthrotomy should be directed straight distally along the medial border of the patellar tendon.

• 4 Quadriceps‐sparing approach 15, 19

  A curvilinear skin incision should be made from the superior pole of the patella to the tibial joint line just medial to the patella and patellar tendon. The arthrotomy should be performed in line with the skin incision beginning at the superomedial border of the patella.

Advantages and disadvantages

• 1 Advantages

  Some surgeons have adopted MIS to minimize muscle damage, promote rehabilitation, improve functional outcomes, reduce blood loss, reduce post‐operative pain, and improve the cosmetic result ¹⁹ .

• 2 Disadvantages

  Minimally invasive surgical exposures may predispose to implant malalignment due to the reduced intraoperative visual field, which can lead to increased polyethylene wear, premature loosening and instability. There may also be a significant learning curve for this form of surgery.

Indications and contraindications

• 1Indications
  • a. Knee varus angle <15°, valgus angle <20°, flexion contracture <10°, range of motion ≥90°.
  • b. The femoral condyle has a moderate width and the patellar tendon is longer. The wider the femoral condyle, the larger the femoral condyle prosthesis implanted. If the patellar ligament is too short to move the patella laterally, then more tissue needed to be released.
• 2 Relative contraindications
  • a. Obesity.
  • b. Patients needing extra operations, such as complicated and revision arthroplasties.
  • c. Osteoporosis.
  • d. Patella baja.
• 3 Absolute contraindications
  • a. Rheumatoid or septic arthritis.
  • b. Diabetes.
  • c. Long‐term use of steroids.
  • d. Revision surgery.
  • e. History of previous knee surgery.
  • f. Joint stiffness.

Surgical features of MIS‐TKA

• 1 Surgical instruments
  • a. Modified instruments.

    Due to the limited space, specialized instrumentation is critical for performing MIS‐TKA. It is impossible to perform the procedure using conventional instruments.

  • b. CAOS.

    For inexperienced surgeons, the reduced surgical field may result in incorrect osteotomy and soft tissue balance during MIS‐TKA. Some surgeons have advocated the use of computer navigation to improve the accuracy of implant positioning during MIS‐TKA.

• 2 Surgical technique
  • a. Surgeons should start with a conventional incision and then shorten the incision length (<14 cm) over time to ensure surgical accuracy and patient safety.
  • b. Appropriate knee flexion and extension helps to expose the knee during MIS‐TKA.
  • c. “Moving window” technology. See the related paragraph under MIS‐THA (2b of section entitled “Surgical features of MIS‐THA”.
  • d. Protection of the extensor mechanism.

    The mid‐vastus and subvastus approaches tend to protect the vastus medialis muscle to the greatest extent, reducing damage to the extensor mechanism, and thereby speeding up functional recovery of the knee.

  • e. Protection of the suprapatellar bursa.

    During standard TKA the suprapatellar bursa is released and the patella everted, which lead to damage to the quadriceps. The patella should be removed laterally rather than be everted during MIS‐TKA.

  • f. Performance of the osteotomy.

    To increase the exposure and operating space, and avoid excessive damage to soft tissues, the procedures of MIS should be performed in a different sequence than that conventionally used for osteotomy. Completing the osteotomy by the standard pattern is often difficult. Therefore, modified instrumentation and the “moving window” technique should be used to perform the osteotomy in several stages. When patellar replacement is performed, the patellar surface is resected first; after which proximal tibial osteotomy is performed. Thus, more surgical space can be obtained for performing the distal femoral resection.

  • g. Minimal joint capsule damage.

    The tibial and femoral osteotomies should be performed in situ to avoid knee dislocation. If osteotomy is performed with the knee dislocated, more extensive joint capsule damage and tissue release will occur, aggravating postoperative pain, and prolonging recovery.

• 3 Pain management and rehabilitation

  Systematic perioperative pain management, including intravenous and epidural analgesia, nerve blocks, pain killer pumps, perioperative oral analgesic drugs, and physical cooling should be used. Rehabilitation during the early postoperative phase using ice therapy, elastic stockings, continuous passive movement and so on may reduce postoperative pain and prevent deep vein thrombosis. Physical therapy may help patients improve the range of motion of the knee, muscle strength, and quality of daily life, as well as enable them to return to work in a safe and timely manner following MIS‐TJA. If the patients are in good physical condition, they may be allowed to ambulate 1–2 days post operation.

Complications

Minimally invasive surgery for total knee arthroplasty, with the smaller incisions and limited exposures, may be result in postoperative complications, including implant malposition, excessive osteotomy, wound problems, periprosthetic fractures, muscle damage, and hematomas.

Summary

MIS‐TJA, which still has many limitations, is currently in its infancy. Surgeons wishing to perform MIS‐TJA should be familiar with conventional THA, receive formal training, and understand the key points of MIS‐TJA techniques. Minimally invasive procedures should be performed with special instruments, a professional surgical team, appropriate surgical indications, deliberate preoperative planning, meticulous surgical procedures and active postoperative functional exercise, all of which will reduce postoperative complications and improve clinical outcomes.

Attendees: Hai‐fu Bu, Xiao‐chun Wei, Jian‐hua Yu, Hong‐qing Ma, Ruo‐fan Ma, Yi‐sheng Wang, Zhi‐yi Wang, Kun‐Zheng Wang, Guo‐zhang Feng, Zhan‐Jun Shi, Qiang Liu, Tie‐bing Qu, Qing‐sheng Zhu, Zhen‐an Zhu, Shi‐gui Yan, Jia‐kuo Yu, Nan‐sheng Yu, Hai‐shan Wu, Ke Zhang, Xian‐long Zhang, Shu‐dong Zhang, Zi‐rong Li, Kang‐hua Li, Liu Yang, Qing‐ming Yang, Shu‐hua Yang, Bin Shen, Gui‐Xing Qiu, An‐Ming Chen, Bai‐Cheng Chen, Yi‐Xiong Zhou, Yong‐gang Zhou, Wei‐ming Fan, Qun‐Hua Jing, Zhen‐gang Cha, Yong‐cheng Hu, Qi‐li Fei, De‐Wei Zhao, Wei‐Dong Xu, Xi‐Sheng Wen, Yue‐Kun Gong, Bing‐fang Zeng, Pei‐jian Dong, Wei‐ming Liao, Fu‐xing Pei, Ke‐rong Dai.