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Minimally Invasive Total Knee Arthroplasty With a Subvastus Approach
Minimally Invasive Total Knee Arthroplasty With a Subvastus Approach Kenneth Gustke, MD Minimally invasive knee-replacement surgery should not be just using a smaller skin incision. The goal of minimally invasive surgery is to maximize the potential for accelerated rehabilitation, which can be achieved by not violating the quadriceps. Using specially designed smaller instrumentation allows performance of the Zimmer Natural Knee total knee replacement (Warsaw, IN) from a familiar frontal orientation through a short incision and with a muscle-sparing subvastus approach. Comparison of results to a standard surgical approach demonstrates less pain and faster rehabilitation without an increase in surgical time or complications. Oper Tech Orthop 16:153-158 © 2006 Elsevier Inc. All rights reserved. KEYWORDS total knee replacement, minimally invasive total knee replacement, subvastus approach, Natural Knee
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n total knee arthroplasty, not cutting the quadriceps muscle should allow patients to have control of their quadriceps earlier during the process of recovery. The patient is usually able to straight leg raise in the recovery room. Because they can straight leg on their own, when transferring from bed to chair and standing, they will be less dependent on the assistance of others. The patient will achieve a high functional level and independence faster than with conventional quadriceps-splitting methods. Using a surgical technique with a small incision and subvastus approach,1,2 our data showed that these patients had less pain, could ambulate farther each day in the hospital, and could progress to using a cane faster.
Indications Because the exposure is more limited than with a conventional approach, the potential for malalignment of components is greater. With a smaller incision, there is a tendency toward more vigorous retraction, which can lead to skin complications. Therefore, not every patient is a suitable candidate for this approach. The challenging cases are those patients who are very heavy or muscular, who have previous surgical scarring, or who have a severe deformity. These patients may be better managed with a standard length incision and subvastus approach or standard length incision with a quadriceps-splitting approach. The greater the surgeon’s exFlorida Orthopaedic Institute, Tampa, FL. Address reprint requests to Kenneth Gustke, MD, Florida Orthopaedic Institute, 13020 North Telecom Parkway, Temple Terrace, FL 33637
1048-6666/06/$-see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1053/j.oto.2006.05.003
perience, the more he or she can consider the short incision and subvastus approach for the more challenging cases. Most importantly, this approach allows for a bailout if too difficult an exposure occurs. The first bailout step is to extend the incision, the second is to incise the vastus medialis from the medial side of the patella up to the superior pole, and the third is to perform a paramedian split of the quadriceps.
Technique Preparation The procedure can be performed with or without a tourniquet. Because exposure is more limited and not all of the procedure is performed in hyperflexion, using a tourniquet improves visualization. A gel pad roll is used under the ipsilateral hip to eliminate external rotation of the limb. Most of the surgery is performed in either 60° or 110° of flexion. Two adjacent gel pads at the foot are used to hold the knee at these 2 positions of flexion. A small gel pad is used proximally for the 110° position. A larger gel pad is place adjacent to the first distally. This is used for the 60° position. Good muscle relaxation is critical. Use of a spinal anesthesia or complete paralysis is recommended.
Exposure A 10- to 12-cm long incision is made extending from the medial side of the tibial tubercle to the superomedial pole of the patella (Fig. 1). Having the proximal incision slightly medial to the midline makes the initial dissection of the vas153
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K. Gustke
Figure 1 Skin incision from superomedial pole of patella to medial side of tibial tubercle. (Color version of figure is available online.)
Figure 3 The medial retinaculum is incised to the distal attachment of the vastus medialis. (Color version of figure is available online.)
tus medialis easier. To create a mobile skin window, the dissection is performed to the lateral border of the patella. The medial dissection is made to the intermuscular septum, preferably leaving the enveloping fascia of the vastus medialis. If the fascial covering is maintained all the way to the intermuscular septum, it must be incised at the intermuscular septum to elevate the vastus medialis from the intermuscular septum. The vastus medialis is easily elevated from the intermuscular septum digitally (Fig. 2). This part of the procedure is simplified if the leg is in a figure-four position. There is no neurovascular structure violated in this plane. Digitally, the vastus medialis is elevated from the suprapatellar pouch. The medial parapatellar retinaculum is incised from the medial side of the tibial tubercle, just off the medial edge of the patella to the midline of the patella, where the vastus medialis typically attaches to the medial patella (Fig. 3). There is about a 2-cm attachment of the vastus medialis to the medial patellar retinaculum. This is incised horizontally while the surgeon’s finger elevates the vastus medialis, creating an “L”-shaped incision (Fig. 4). The suprapatellar pouch is then incised vertically (Fig. 5). Medial and lateral femoral osteophytes, and any large patellar
osteophytes, are removed, which should allow the patella to subluxate into the lateral gutter. A curved retractor is placed at the level of the tendonous attachment of the vastus medialis to the patella. Another curved retractor is placed superomedially. The knee is placed into 60° of flexion. Two addi-
Figure 2 Vastus medialis is digitally elevated from the intermuscular septum. (Color version of figure is available online.)
Figure 4 Incision of the vastus medialis attachment from the medial retinaculum. (Color version of figure is available online.)
Figure 5 Incision of the suprapatellar pouch. (Color version of figure is available online.)
Minimally invasive TKA with a subvastus approach
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Figure 6 Initial exposure of the distal femur. (Color version of figure is available online.)
Figure 8 Osteotomy of the distal femur. (Color version of figure is available online.)
tional curved retractors are placed at the joint line level. Part of the patellar fat pad is incised to view the lateral compartment. The anterior horns of the medial and lateral menisci and the anterior cruciate ligament are removed. At this point, there should be adequate exposure of the medial and lateral femoral condyles (Fig. 6). If not, the extensor mechanism needs to be further mobilized either by more proximal dissection of the vastus medialis from the intermuscular septum, more skin incision proximally, incision of the vastus medialis up to the superior pole of the patella, or performing a standard paramedian quadriceps-splitting approach, in that order.
The following surgical technique and instrumentation described is for the Zimmer Natural Knee System (Zimmer, Inc, Warsaw, IN). The technique allows for posterior cruciate retaining or sacrificing, and cement or cementless fixation of components. The intermedullary canal is entered with a drill hole just anterior to the origin of the posterior cruciate ligament. A small distal femoral cutting guide is inserted with the intermedullary rod. With the knee in the 110° flexed posi-
tion, the guide is pinned into place in the desired rotation (Fig. 7). At the 110 ° flexed position, the anterior distal femur is hidden under skin. The knee is now placed into the 60° flexed position which exposes and allows resection of the distal femur using the standard distal femoral cutting block (Fig. 8). The knee is placed in 110° of flexion. The small distal femoral sizing guide is applied to the distal femur using the posterior femoral condyles, transepicondylar line or trochlear groove as a rotational reference. The holes for the anteroposterior femoral cutting block are drilled. The stylus tip is placed under the quadriceps against the anterior cortex to determine the femoral component size (Fig. 9). With a short incision, it is impossible to simultaneously visualize the posterior femoral condyles and the anterior distal femur with the knee held in one position as is typical with a standard approach. Using an all-in-one cutting block for the distal femur risks anterior cortical notching due to lack of visualization or damage to the undersurface of the quadriceps from the saw. This is because the anterior femur is hidden under the skin flap. It is for that reason, that the Natural Knee instrumentation was designed to perform the osteotomies of the posterior femur with a separate block than for the anterior
Figure 7 Application of the distal femoral alignment guide. (Color version of figure is available online.)
Figure 9 Femoral component sizing. (Color version of figure is available online.)
Femoral Preparation
K. Gustke
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Figure 10 Posterior femoral osteotomies. (Color version of figure is available online.)
Figure 13 Proximal tibial exposure. (Color version of figure is available online.)
femur. With the Natural Knee measured resection system, the posterior femoral resections are the same. Either a small or large posterior femoral cutting block is applied depending on the width of the femur (Fig. 10). The posterior femoral condyle and posterior chamfer cuts are made. The size specific anterior femoral block is used to make the anterior fe-
mur, anterior femoral chamfer and patellar notch cuts (Figs. 11 and 12). These cuts are made with the knee in 60° of flexion to allow direct visualization of the saw blade as it exits the anterior femoral cortex.
Tibial Preparation The proximal tibia can be subluxated anterior to the femur if the deep medial collateral ligament and medial capsule are released to past the midline of the medial tibial condyle. A heavy double-pronged retractor is placed laterally. Direct visualization of the entire proximal tibia is usually possible (Fig. 13). What is left of the menisci is resected. The tibial alignment guide is applied in the appropriate varus/valgus position. The instrument is adjusted to allow for a tibial cut parallel to the existing slope. The proximal tibia is resected in one piece using the pinned proximal tibial cutting block while protecting the posterior cruciate with a half-inch osteotome placed in front of it (Fig. 14). The appropriate size tibial drill guide that maximally covers the tibia without overhang is pinned in the correct rotation. The central stem punch is inserted (Fig. 15). The drill guide is removed. With the knee flexed and femur distracted anteriorly, any posterior
Figure 11 Anterior femoral osteotomy. (Color version of figure is available online.)
Figure 12 Anterior femoral chamfer osteotomy. (Color version of figure is available online.)
Figure 14 Proximal tibial osteotomy. (Color version of figure is available online.)
Minimally invasive TKA with a subvastus approach
Figure 15 Preparation for tibial component stem. (Color version of figure is available online.)
femoral or remaining intercondylar notch osteophytes are removed.
Patellar Preparation If patella resurfacing is desired, the patella is able to be partially everted due to joint decompression following the femoral and tibial bone resections. It is osteotomized, sized and drilled (Fig. 16). The patella trial is applied to confirm maximal coverage without overhang.
Trialing The trial tibial and femoral components are inserted and the knee checked for range of motion, varus and valgus stability, and posterior cruciate function. There is no difficulty in performing medial or lateral collateral ligament or iliotibial band releases if necessary. The posterior cruciate is resected if it is incompetent to a forced posterior drawer test or if it is too tight causing excessive femoral rollback.
Implant Insertion The implants can be inserted with or without cement depending on bone quality and surgeon’s preference. If full
Figure 16 Patellar component preparation. (Color version of figure is available online.)
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Figure 17 Tibial component cementation. (Color version of figure is available online.)
cement fixation is desired, the tibial, femoral and patellar components can be cemented using one batch of cement, in that order (Fig. 17).
Soft-Tissue Closure Because of the intact vector forces on the patellar due to the intact quadriceps mechanism, it is rare that a lateral patellar retinacular release is required (Fig. 18). The incision in the suprapatellar pouch is closed with absorbable suture. The “L-shaped” incision in the medial patellar retinaculum is closed with delayed absorbable suture. Drains are usually place deep to the fascia and superficially along the intermuscular septum medially. The subcutaneous tissue and skin are closed.
Postoperative Management Weight-bearing activity as tolerated is started immediately. Physical therapy emphasizes active and active assisted range of motion.
Figure 18 Intact quadriceps mechanism. (Color version of figure is available online.)
K. Gustke
158
Pitfalls Any patient with conditions that will limit lateral patellar subluxation will compromise the ability to perform this technique. This includes patients with lateral scarring from previous incisions. Long-term durability relates directly to implant alignment. Long-term durability is far more important than a short-term accelerated recovery. Therefore, if there is any difficulty in completing the procedure with accurate component alignment, additional exposure must be obtained.
erage longer tourniquet time of 7 minutes, but a 5-minute total surgical time due to a quicker closure time. The MIS group had an average 10% less blood loss. The MIS group had an easier initial rehabitation. A total of 88% of MIS patients can straight leg raise on the day of surgery, which allows for easier transfers. For the first 3 days after surgery, the MIS group could walk twice as far. Most importantly, the MIS cases had no significant complications. Axial alignment was satisfactory in all. There were no hematomas, wound complications, or infections.
Results
Conclusions
The first 100 short incision subvastus minimally invasive total knee replacements were compared with a matched set 50 non-MIS knees. They were matched for age, sex, diagnosis, Charnley class, body mass index, and deformity. The anesthesia and rehabilitation were not changed, only the surgical technique to determine the true effect of the different surgical technique. Pain (0 to 10 scale) was significantly less for first 6 weeks for the MIS group (day 1: 3.7 versus 4.9, day 2: 2.7 versus. 4.2, day 3: 2.0 versus 2.8, week 2: 3.2 versus 4, and week 6: 1.6 versus 2.3). Average maximum flexion was greater for the MIS group for the first 6 weeks (day 1: 82 versus 74, day 2: 84 versus 80, day 3: 84 versus 80, week 2: 95 versus 87, week 6: 109 versus 104). There was no significant difference in surgical time. The MIS group had an av-
The short incision subvastus minimally invasive total knee replacement is easy to learn. The surgical technique follows same steps and orientation of a standard technique. The results are no worse than with a standard approach, so excellent long-term results can still be expected. The potential short-term advantage of faster rehabilitation and slightly less pain makes it an attractive technique for many total knee patients.
References 1. Hofmann AA, Plaster RL, Murdock LE: Subvastus (Southern) approach for primary total knee arthroplasty. Clin Orthop 269:70-77, 1991 2. Smigielski M, Gustke KA: Southern approach for total knee replacement. Florida Orthop Trans 1989
I
n total knee arthroplasty, not cutting the quadriceps muscle should allow patients to have control of their quadriceps earlier during the process of recovery. The patient is usually able to straight leg raise in the recovery room. Because they can straight leg on their own, when transferring from bed to chair and standing, they will be less dependent on the assistance of others. The patient will achieve a high functional level and independence faster than with conventional quadriceps-splitting methods. Using a surgical technique with a small incision and subvastus approach,1,2 our data showed that these patients had less pain, could ambulate farther each day in the hospital, and could progress to using a cane faster.
Indications Because the exposure is more limited than with a conventional approach, the potential for malalignment of components is greater. With a smaller incision, there is a tendency toward more vigorous retraction, which can lead to skin complications. Therefore, not every patient is a suitable candidate for this approach. The challenging cases are those patients who are very heavy or muscular, who have previous surgical scarring, or who have a severe deformity. These patients may be better managed with a standard length incision and subvastus approach or standard length incision with a quadriceps-splitting approach. The greater the surgeon’s exFlorida Orthopaedic Institute, Tampa, FL. Address reprint requests to Kenneth Gustke, MD, Florida Orthopaedic Institute, 13020 North Telecom Parkway, Temple Terrace, FL 33637
1048-6666/06/$-see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1053/j.oto.2006.05.003
perience, the more he or she can consider the short incision and subvastus approach for the more challenging cases. Most importantly, this approach allows for a bailout if too difficult an exposure occurs. The first bailout step is to extend the incision, the second is to incise the vastus medialis from the medial side of the patella up to the superior pole, and the third is to perform a paramedian split of the quadriceps.
Technique Preparation The procedure can be performed with or without a tourniquet. Because exposure is more limited and not all of the procedure is performed in hyperflexion, using a tourniquet improves visualization. A gel pad roll is used under the ipsilateral hip to eliminate external rotation of the limb. Most of the surgery is performed in either 60° or 110° of flexion. Two adjacent gel pads at the foot are used to hold the knee at these 2 positions of flexion. A small gel pad is used proximally for the 110° position. A larger gel pad is place adjacent to the first distally. This is used for the 60° position. Good muscle relaxation is critical. Use of a spinal anesthesia or complete paralysis is recommended.
Exposure A 10- to 12-cm long incision is made extending from the medial side of the tibial tubercle to the superomedial pole of the patella (Fig. 1). Having the proximal incision slightly medial to the midline makes the initial dissection of the vas153
154
K. Gustke
Figure 1 Skin incision from superomedial pole of patella to medial side of tibial tubercle. (Color version of figure is available online.)
Figure 3 The medial retinaculum is incised to the distal attachment of the vastus medialis. (Color version of figure is available online.)
tus medialis easier. To create a mobile skin window, the dissection is performed to the lateral border of the patella. The medial dissection is made to the intermuscular septum, preferably leaving the enveloping fascia of the vastus medialis. If the fascial covering is maintained all the way to the intermuscular septum, it must be incised at the intermuscular septum to elevate the vastus medialis from the intermuscular septum. The vastus medialis is easily elevated from the intermuscular septum digitally (Fig. 2). This part of the procedure is simplified if the leg is in a figure-four position. There is no neurovascular structure violated in this plane. Digitally, the vastus medialis is elevated from the suprapatellar pouch. The medial parapatellar retinaculum is incised from the medial side of the tibial tubercle, just off the medial edge of the patella to the midline of the patella, where the vastus medialis typically attaches to the medial patella (Fig. 3). There is about a 2-cm attachment of the vastus medialis to the medial patellar retinaculum. This is incised horizontally while the surgeon’s finger elevates the vastus medialis, creating an “L”-shaped incision (Fig. 4). The suprapatellar pouch is then incised vertically (Fig. 5). Medial and lateral femoral osteophytes, and any large patellar
osteophytes, are removed, which should allow the patella to subluxate into the lateral gutter. A curved retractor is placed at the level of the tendonous attachment of the vastus medialis to the patella. Another curved retractor is placed superomedially. The knee is placed into 60° of flexion. Two addi-
Figure 2 Vastus medialis is digitally elevated from the intermuscular septum. (Color version of figure is available online.)
Figure 4 Incision of the vastus medialis attachment from the medial retinaculum. (Color version of figure is available online.)
Figure 5 Incision of the suprapatellar pouch. (Color version of figure is available online.)
Minimally invasive TKA with a subvastus approach
155
Figure 6 Initial exposure of the distal femur. (Color version of figure is available online.)
Figure 8 Osteotomy of the distal femur. (Color version of figure is available online.)
tional curved retractors are placed at the joint line level. Part of the patellar fat pad is incised to view the lateral compartment. The anterior horns of the medial and lateral menisci and the anterior cruciate ligament are removed. At this point, there should be adequate exposure of the medial and lateral femoral condyles (Fig. 6). If not, the extensor mechanism needs to be further mobilized either by more proximal dissection of the vastus medialis from the intermuscular septum, more skin incision proximally, incision of the vastus medialis up to the superior pole of the patella, or performing a standard paramedian quadriceps-splitting approach, in that order.
The following surgical technique and instrumentation described is for the Zimmer Natural Knee System (Zimmer, Inc, Warsaw, IN). The technique allows for posterior cruciate retaining or sacrificing, and cement or cementless fixation of components. The intermedullary canal is entered with a drill hole just anterior to the origin of the posterior cruciate ligament. A small distal femoral cutting guide is inserted with the intermedullary rod. With the knee in the 110° flexed posi-
tion, the guide is pinned into place in the desired rotation (Fig. 7). At the 110 ° flexed position, the anterior distal femur is hidden under skin. The knee is now placed into the 60° flexed position which exposes and allows resection of the distal femur using the standard distal femoral cutting block (Fig. 8). The knee is placed in 110° of flexion. The small distal femoral sizing guide is applied to the distal femur using the posterior femoral condyles, transepicondylar line or trochlear groove as a rotational reference. The holes for the anteroposterior femoral cutting block are drilled. The stylus tip is placed under the quadriceps against the anterior cortex to determine the femoral component size (Fig. 9). With a short incision, it is impossible to simultaneously visualize the posterior femoral condyles and the anterior distal femur with the knee held in one position as is typical with a standard approach. Using an all-in-one cutting block for the distal femur risks anterior cortical notching due to lack of visualization or damage to the undersurface of the quadriceps from the saw. This is because the anterior femur is hidden under the skin flap. It is for that reason, that the Natural Knee instrumentation was designed to perform the osteotomies of the posterior femur with a separate block than for the anterior
Figure 7 Application of the distal femoral alignment guide. (Color version of figure is available online.)
Figure 9 Femoral component sizing. (Color version of figure is available online.)
Femoral Preparation
K. Gustke
156
Figure 10 Posterior femoral osteotomies. (Color version of figure is available online.)
Figure 13 Proximal tibial exposure. (Color version of figure is available online.)
femur. With the Natural Knee measured resection system, the posterior femoral resections are the same. Either a small or large posterior femoral cutting block is applied depending on the width of the femur (Fig. 10). The posterior femoral condyle and posterior chamfer cuts are made. The size specific anterior femoral block is used to make the anterior fe-
mur, anterior femoral chamfer and patellar notch cuts (Figs. 11 and 12). These cuts are made with the knee in 60° of flexion to allow direct visualization of the saw blade as it exits the anterior femoral cortex.
Tibial Preparation The proximal tibia can be subluxated anterior to the femur if the deep medial collateral ligament and medial capsule are released to past the midline of the medial tibial condyle. A heavy double-pronged retractor is placed laterally. Direct visualization of the entire proximal tibia is usually possible (Fig. 13). What is left of the menisci is resected. The tibial alignment guide is applied in the appropriate varus/valgus position. The instrument is adjusted to allow for a tibial cut parallel to the existing slope. The proximal tibia is resected in one piece using the pinned proximal tibial cutting block while protecting the posterior cruciate with a half-inch osteotome placed in front of it (Fig. 14). The appropriate size tibial drill guide that maximally covers the tibia without overhang is pinned in the correct rotation. The central stem punch is inserted (Fig. 15). The drill guide is removed. With the knee flexed and femur distracted anteriorly, any posterior
Figure 11 Anterior femoral osteotomy. (Color version of figure is available online.)
Figure 12 Anterior femoral chamfer osteotomy. (Color version of figure is available online.)
Figure 14 Proximal tibial osteotomy. (Color version of figure is available online.)
Minimally invasive TKA with a subvastus approach
Figure 15 Preparation for tibial component stem. (Color version of figure is available online.)
femoral or remaining intercondylar notch osteophytes are removed.
Patellar Preparation If patella resurfacing is desired, the patella is able to be partially everted due to joint decompression following the femoral and tibial bone resections. It is osteotomized, sized and drilled (Fig. 16). The patella trial is applied to confirm maximal coverage without overhang.
Trialing The trial tibial and femoral components are inserted and the knee checked for range of motion, varus and valgus stability, and posterior cruciate function. There is no difficulty in performing medial or lateral collateral ligament or iliotibial band releases if necessary. The posterior cruciate is resected if it is incompetent to a forced posterior drawer test or if it is too tight causing excessive femoral rollback.
Implant Insertion The implants can be inserted with or without cement depending on bone quality and surgeon’s preference. If full
Figure 16 Patellar component preparation. (Color version of figure is available online.)
157
Figure 17 Tibial component cementation. (Color version of figure is available online.)
cement fixation is desired, the tibial, femoral and patellar components can be cemented using one batch of cement, in that order (Fig. 17).
Soft-Tissue Closure Because of the intact vector forces on the patellar due to the intact quadriceps mechanism, it is rare that a lateral patellar retinacular release is required (Fig. 18). The incision in the suprapatellar pouch is closed with absorbable suture. The “L-shaped” incision in the medial patellar retinaculum is closed with delayed absorbable suture. Drains are usually place deep to the fascia and superficially along the intermuscular septum medially. The subcutaneous tissue and skin are closed.
Postoperative Management Weight-bearing activity as tolerated is started immediately. Physical therapy emphasizes active and active assisted range of motion.
Figure 18 Intact quadriceps mechanism. (Color version of figure is available online.)
K. Gustke
158
Pitfalls Any patient with conditions that will limit lateral patellar subluxation will compromise the ability to perform this technique. This includes patients with lateral scarring from previous incisions. Long-term durability relates directly to implant alignment. Long-term durability is far more important than a short-term accelerated recovery. Therefore, if there is any difficulty in completing the procedure with accurate component alignment, additional exposure must be obtained.
erage longer tourniquet time of 7 minutes, but a 5-minute total surgical time due to a quicker closure time. The MIS group had an average 10% less blood loss. The MIS group had an easier initial rehabitation. A total of 88% of MIS patients can straight leg raise on the day of surgery, which allows for easier transfers. For the first 3 days after surgery, the MIS group could walk twice as far. Most importantly, the MIS cases had no significant complications. Axial alignment was satisfactory in all. There were no hematomas, wound complications, or infections.
Results
Conclusions
The first 100 short incision subvastus minimally invasive total knee replacements were compared with a matched set 50 non-MIS knees. They were matched for age, sex, diagnosis, Charnley class, body mass index, and deformity. The anesthesia and rehabilitation were not changed, only the surgical technique to determine the true effect of the different surgical technique. Pain (0 to 10 scale) was significantly less for first 6 weeks for the MIS group (day 1: 3.7 versus 4.9, day 2: 2.7 versus. 4.2, day 3: 2.0 versus 2.8, week 2: 3.2 versus 4, and week 6: 1.6 versus 2.3). Average maximum flexion was greater for the MIS group for the first 6 weeks (day 1: 82 versus 74, day 2: 84 versus 80, day 3: 84 versus 80, week 2: 95 versus 87, week 6: 109 versus 104). There was no significant difference in surgical time. The MIS group had an av-
The short incision subvastus minimally invasive total knee replacement is easy to learn. The surgical technique follows same steps and orientation of a standard technique. The results are no worse than with a standard approach, so excellent long-term results can still be expected. The potential short-term advantage of faster rehabilitation and slightly less pain makes it an attractive technique for many total knee patients.
References 1. Hofmann AA, Plaster RL, Murdock LE: Subvastus (Southern) approach for primary total knee arthroplasty. Clin Orthop 269:70-77, 1991 2. Smigielski M, Gustke KA: Southern approach for total knee replacement. Florida Orthop Trans 1989