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A comparison of the midvastus and paramedian approaches for total knee arthroplasty
The Journal of Arthroplasty Vol. 14 No. 1 1999
A Comparison of the Midvastus and P a r a m e d i a n A p p r o a c h e s for Total Knee Arthroplasty D a v i d F. D a l u r y , M D , * a n d W i l l i a m A. J i r a n e k , MD -[
Abstract: This prospective, double-blinded evaluation of 24 osteoarthritic patients
undergoing bilateral total knee replacement compared the midvastus and standard parapatellar approaches. The midvastus approach was found to offer an early advantage in terms of less pain and earlier return to function. There were no significant complications associated with the midvastus approach. This approach should be a part of the knee surgeon's armamentarium. Key words: total knee arthroplasty, midvastus approach, surgical approaches to the knee, total knee rehabilitation.
and involves the standard anterior midline skin incision followed by a deeper dissection that splits the vastus medialis obliquus (VMO) muscle in the direction of its fibers at its insertion into the superiormedial pole of the patella (Fig. 1 ). The distal portion of the capsular incision is identical to the routine parapatellar incision. The major advantage of this approach is the preservation of the extensor mechanism from surgical trauma. This approach has many potential benefits, including improved blood supply to the patella [5-7], fewer patellofemoral tracking problems, earlier return to function of the extensor mechanism, and less postoperative pain. This prospective, randomized, controlled study compares the standard parapatellar approach with the midvastus approach in a series of one-stage bilateral total knee replacements performed by a single surgeon.
Total knee replacement has become an accepted treatment for end-stage degenerative joint disease of the knee. The technique has become refined over the years so that now the majority of patients receive reproducible and durable relief of pain and return to function. There has been a focus on surgical technique and rehabilitation protocols as a means of improving patient outcomes. The standard midline medial parapatellar approach, initially described by Von Langenbeck in 1879 [1] provides excellent exposure to the knee and has widespread popularity and a long track record of follow-up. There have been modifications to this approach by many authors, including the straight midline approach [21, the subvastus approach [3,4], and the lateral approach. This article studies the midvastus approach and compares it with the standard parapatellar approach in a group of matched controls. The midvastus approach has been popularized by Engh (personal communication, 1994) and others
Materials and Methods Twenty-four consecutive one-stage bilateral knee replacements composed the study group. The preoperative diagnosis was osteoarthritis in all 24 patients and 48 knees. There were 16 w om en and 8 men. All procedures were performed by a single surgeon (D.ED.) via an anterior midline skin incision, and the decision as to which knee received which approach was
From *Towson Orthopaedic Associates, Johns Hopkins Hospital, Towson, MD; and ~-Tuckahoe Orthopaedics, Medical College of Virginia, VA. Submitted June 5, I997; accepted April 28, 1998. Reprint requests: David F. Dalury, MD, Towson Orthopaedic Associates, 8322 Bellona Avenue, Towson, MD 21204. Copyright © 1999 by Churchill Livingstone® 0883- 5403 / 1401-0006510.00/0
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34
The Journal of Arthroplasty Vol. 14 No. 1 January 1999
Muscular Branch of Femoral N, henous N.
Fig. 1. Pertinent anatomy of the medial aspect of the knee.
henous Branch escending icular A. Articular Branch of Descending Genicular A.
~rior Branch escending icular A.
Lpatellar Branch aphenous N. lial Inferior icular A.
made at the time of surgery by the surgeon without regard to any preexisting criteria. All procedures were performed u n d e r regional anesthesia, and postoperative pain was managed using patientcontrolled analgesia pumps. All procedures were done u n d e r tourniquet, which was released before closure. Drains were used in all knees. All knees were posterior cruciate ligament (PCL) preserving, and all three c o m p o n e n t s were cemented. All patients received elastic stockings, intermittent compression stockings, and aspirin that was continued for 6 weeks for deep vein thrombosis prophylaxis. Preoperative alignment, range of m o t i o n (ROM), and Cybex muscle testing was done on all knees. Muscle testing on the Cybex was done at both 30 ° and 60 ° to test peak maximal torque. This testing was done preoperatively and at 6 and 12 weeks postoperatively. Physical therapists, nursing staff, and patients were blinded as to which knee had which approach. Constant passive m o t i o n (CPM) was used starting in the recovery room and continued while the patient was hospitalized, for approxi-
mately 8 hours a day, alternating each knee. Physical therapy was begun on postoperative day (POD) 1 with weight bearing as tolerated, ROM exercises, and gait training continued twice a day during the hospital stay. The tourniquet times, ROM at capsular closure, h e m o v a c drainage, visual analog pain scales, time to straight leg raising (SLR), and ROM at hospital discharge were recorded, and ROM was recorded at 6 and 12 weeks postoperatively. Radiographic analysis included anteroposterior, lateral, and sunrise views at 6 and 12 weeks.
Technique of the Midvastus Approach A standard midline skin incision was made, t h e n the fascia overlying the VMO was dissected free from the subcutaneous fat. The VMO muscle belly was t h e n split in the direction of its fibers, using a knife from a point at the superior-medial border of the patella and extended medially toward the intermuscular septum. The patella was t h e n everted, and
MidvastusApproachtoTKA t h e p r o c e d u r e w a s c a r r i e d o u t in a r o u t i n e f a s h i o n . C l o s u r e i n v o l v e d r e p a i r i n g t h e d e e p fascial l a y e r ( b e l o w t h e m u s c l e ) o n l y d o w n to t h e s u p e r i o r medial border, which was reinforced, then the r o u t i n e m e d i a l a n d i n f e r i o r c a p s u l a r repair.
Results W e s t u d i e d 24 c o n s e c u t i v e b i l a t e r a l t o t a l k n e e r e p l a c e m e n t p a t i e n t s w i t h a n a v e r a g e age of 70 y e a r s . All of t h e p a t i e n t s h a d o s t e o a r t h r i t i s . A v e r a g e w e i g h t for t h e w o m e n w a s 156 lbs a n d for t h e m e n w a s 205 lbs. A v e r a g e p r e o p e r a t i v e R O M w a s c o m p a r a b l e in t h e 2 g r o u p s of k n e e s . G r o u p 1 ( m i d v a s t u s a p p r o a c h ) R O M w a s 8 ° to 118 ° , a n d g r o u p 2 ( s t a n d a r d p a r a p a t e l l a r a p p r o a c h ) R O M w a s 7 ° to 120 ° . T o u r n i q u e t t i m e s w e r e c o m p a r a b l e for t h e 2 g r o u p s : 32 m i n u t e s for g r o u p 1 a n d 33 m i n u t e s for g r o u p 2. E s t i m a t e d b l o o d loss in t h e p o s t o p e r a t i v e d r a i n w a s 370 m L for g r o u p 1 a n d 435 m L for g r o u p 2. T h e r e w e r e n o l a t e r a l r e l e a s e s in g r o u p 1 a n d 3 l a t e r a l r e l e a s e s in g r o u p 2. R a n g e of m o t i o n at 6 w e e k s w a s 50/97 ° for g r o u p 1 a n d n o d i f f e r e n t at 601100 ° for g r o u p 2. At 3 m o n t h s , g r o u p 1 h a d a n arc of m o t i o n of 2 ° / 1 1 1 ° a n d g r o u p 2 h a d 2 ° / 1 1 3 °. T h e r e w e r e n o s i g n i f i c a n t d i f f e r e n c e s n o t i c e d b y e i t h e r g r o u p at 3 m o n t h s compared with the preoperative ROM. Preoperative standing alignment, measured on a s t a n d i n g a n t e r o p o s t e r i o r film, w a s 2 ° v a l g u s in g r o u p 1 ( r a n g e , 14 ° v a l g u s to 4 ° v a r u s ) a n d 3 ° v a l g u s in g r o u p 2 (range, 11 ° v a l g u s to 2 ° v a r u s ) . P o s t o p e r a tive a l i g n m e n t , m e a s u r e d similarly, w a s 6 ° for g r o u p 1 a n d 6.5 ° for g r o u p 2. T h e r e w e r e n o l a t e r a l releases and no patellar dislocations or subluxations in g r o u p 1. G r o u p 2 h a d 3 l a t e r a l r e l e a s e s a n d 2 p a t i e n t s w i t h m i l d p a t e l l a r tilts o n s u n r i s e v i e w at 3 months postoperatively. These conditions were not symptomatic. Quadriceps strength was tested using a Cybex m a c h i n e p r e o p e r a t i v e l y at 30 ° a n d 60 ° a n d at 6 weeks and 3-month intervals postoperatively. There w a s n o statistically significant d i f f e r e n c e in p r e o p e r a tive q u a d r i c e p s s t r e n g t h b e t w e e n t h e 2 g r o u p s , as j u d g e d b y C y b e x t e s t i n g at e i t h e r 30 ° o r 60 ° f l e x i o n (P = .5, a n a l y s i s of v a r i a n c e ) . T h e r e w a s a h i g h l y s i g n i f i c a n t d i f f e r e n c e i n q u a d r i c e p s s t r e n g t h at 6 w e e k s p o s t o p e r a t i v e l y at b o t h 30 ° a n d 60 ° , w i t h g r o u p 1 (the m i d v a s t u s a p p r o a c h ) b e i n g s t r o n g e r (P = .001). A t 3 m o n t h s p o s t o p e r a t i v e l y , t h e r e w a s n o d i f f e r e n c e in q u a d r i c e p s s t r e n g t h b e t w e e n t h e 2 g r o u p s at 30 ° f l e x i o n (P = .4), b u t t h e r e w a s a slight d i f f e r e n c e at 60 ° f l e x i o n , w i t h g r o u p 1 ( m i d v a s t u s a p p r o a c h ) b e i n g s t r o n g e r (P = .04).
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Daluryand Jiranek
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Patients overwhelmingly preferred the knees done via t h e m i d v a s t u s a p p r o a c h . Of t h e 24 p a t i e n t s , 19 e x p r e s s e d a p r e f e r e n c e a n d 5 d i d n o t . Of t h e 19 p a t i e n t s w h o h a d a p r e f e r e n c e , 17 p r e f e r r e d t h e midvastus approach, and 2 preferred the parapatellar a p p r o a c h . V i s u a l a n a l o g p a i n scales ( 0 - - n o pain and I0 = maximal pain) were recorded by the nursing staff o n POD 1, 2, a n d 3. Scores w e r e s u b s t a n t i a l l y l o w e r for g r o u p 1: 4.7, 2.9, a n d 2.1 c o m p a r e d w i t h 7.0, 5.8, a n d 4.5 for g r o u p 2. G r o u p 1 h a d a n e a r l i e r r e t u r n to SLR a n d w e r e a b l e to SLR in b e d a n a v e r a g e of 1.7 d a y s p o s t o p e r a t i v e l y v e r s u s 5.2 d a y s p o s t o p e r a t i v e l y in g r o u p 2 (Table 1). The o v e r a l l c o m p l i c a t i o n r a t e for b o t h g r o u p s w a s small. T h e r e w e r e 3 s u p e r f i c i a l h e m a t o m a s e x t e n d i n g u p i n t o t h e g r o i n in g r o u p 1 a n d n o n e in g r o u p 2. T h e s e w e r e t r a n s i e n t a n d d i d n o t i n f l u e n c e e v e n t u a l a r c of m o t i o n , r e h a b i l i t a t i o n , t r a n s f u s i o n rates, p a i n levels, o r p a t i e n t satisfaction. T h e r e w e r e n o w o u n d h e a l i n g p r o b l e m s a n d n o i n f e c t i o n s in either group. T h e r e w a s n o clinical e v i d e n c e of d e e p v e n o u s t h r o m b o s i s in e i t h e r g r o u p , a l t h o u g h n o r a d i o graphic or Doppler testing was done. There was only o n e m a n i p u l a t i o n r e q u i r e d , a p a t i e n t in g r o u p 2 who had an excellent response and eventual ROM of 4 ° / 1 2 0 ° at 3 m o n t h s p o s t o p e r a t i v e l y .
T a b l e 1. S u m m a r y of Outcomes Comparing M i d v a s t u s and Standard Approach Groups
Group 1 Midvastus
Average preop strength (foot pounds) 300/60 ° Average postop strength (foot pounds) 300/60 ° 6 weeks 12 weeks Return to straight leg raising (average) Range of motion (average) Preop Postop ( 12 weeks) Patellofemoral tracking problems Lateral releases Visual analog pain scale (0 = minimal, 10 - maximal) POD 1 POD 2 POD 3
Group 2 Standard Parapatellar
20•33
19/34
33/46 36•48
25/39 34146
1.7 days
5.2 days
8-118 ° 2-111 °
7-120 ° 2-113 °
0 0
2 patellar tilts 3
4,7 2.9 2.1
7.0 5.8 4.5
Preop, preoperative; postop, postoperative; POD, postoperative day.
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The Journal of Arthroplasty Vol. 14 No. 1 January 1999
Discussion This study was a prospective double-blinded evaluation of 2 different surgical approaches to total knee replacement. In this group of 24 osteoarthritic patients without severe deformity, the midvastus approach appeared to offer an early advantage compared with the standard parapatellar approach. The midvastus knees were less painful, had an earlier r e t u r n to function (earlier SLR, improved quadriceps strength), and were preferred by the patients compared with the standard approach. There were no significant differences in complication rates b e t w e e n the two groups. The advantages of the midvastus approach had dissipated by the 3 - m o n t h follow-up appointment. The less painful and easier rehabilitation, however, can m e a n shorter hospital stays, earlier return to function, and increased patient satisfaction. The demonstrated earlier return to function in the midvastus group most likely has to do with less trauma to the extensor mechanism. This situation allows earlier SLR and return of quadriceps strength and improves patellar tracking. There were no lateral releases in the midvastus group and no subluxations on x-ray versus 3 lateral releases and 2 mild subluxations (different patients) in the standard group. Extensor mechanism problems are the most freq u e n t complications associated with total knee replacement, including subluxation, clicking, dislocation, and avascular necrosis [8-14]. There have been other surgical approaches designed to minimize these complications, in particular, the subvastus approach [3,4]. One of the problems with the subvastus approach is difficulty visualizing the lateral tibial plateau [3]. This difficulty can lead to problems sizing, aligning, and seating the tibial component. Short, stocky, muscular, and obese legs make this problem more difficult. The midvastus approach allows better visualization of the lateral tibial plateau because only one half of the VMO needs to be mobilized as opposed to the entire VMO in the subvastus approach. Tips for minimizing visualization difficulties in challenging knees include slow, gradual knee flexion to take advantage of the viscoelastic potential of the extensor mechanism; an extension of the proximal skin incision, making certain to release Scarpa's fascia the entire length of the skin incision; extension of the medial split in the VMO all the way to the intermuscular septum; and occasionally perform a n c e of a m o r e extensive posteromedial release on the tibia, particularly in a tight varus knee. Occasion-
ally, with tight extensor mechanisms or short legs, the patella is subluxated laterally in flexion (not everted) while the distal femoral cuts are performed. Once these have b e e n done, the patella can t h e n be everted in the usual manner. Using these tips, the midvastus approach can be employed for all but the most difficult knees. There were 3 proximal and medial h e m a t o m a s in the midvastus knees. Although these did not lead to an increased need for transfusion, increased pain, or loss of motion, they certainly could have. The blood supply of the medial portion of the knee is well described. W h e n cutting across the VMO, one must be certain to visualize and electrocoagulate the n u m e r o u s perforating veins and arterial branches crossing the incision. Close attention to excellent hemostasis with inspection after letting the tourniquet d o w n is necessary. Perhaps a more tight or extensive deep fascial layer closure would have eliminated or minimized these hematomas.
Summary In this prospective, randomized, controlled study, the midvastus approach offered m a n y early advantages compared with the standard approach without any increase in the complication rate. This approach has the potential to lead to shorter hospital stays, easier rehabilitation, and increased patient satisfaction. The midvastus approach should become a part of the knee arthroplasty surgeon's a r m a m e n t a r i u m .
References 1. Yon Langenbeck B: Zur resection des kniegellenks. Verhandl d Deutschen Gesellsch f Chit VII:23, 1879 2. Insall J: A midline approach to the knee. J Bone Joint Surg Am 53:1584, 1971 3. Hoffman AA, Plaster RL, Murdock LE: Subvastus (southern) approach for primary total knee arthroplasty. Clin Orthop 269:70, 1991 4. Marie Z, Ott DM, Karpman RR: The standard versus the subvastus (southern) approach for total knee arthroplasty: A randomized prospective study. Orthop Trans 15:43, 1991 5. Kayler DE, Lyttle D: Surgical interruption of patellar blood supply by total knee arthroplasty. Clin Orthop 229:221, 1988 6. Scapinelli R: Blood supply of the human patella. J Bone Joint Surg 49:563, 1967 7. Scuderi G, Scharf SC, Meltzer BA, Scott WN: The relationship of lateral releases to patellar viability in total knee arthroplasty. J Arthroplasty 2:209, 1987 8. Brick GW, Scott RD: The patellar femoral component of total knee arthroplasty. Clin Orthop 231:163, 1988
MidvastusApproach toTKA 9. Cameron H, Fedorkow DM: The patella in total knee arthroplasty. Clin Orthop 165:197, 1982 10. Clayton ML, Thirupathi R: Patellar complications after total condylar arthroplasty. Clin Orthop 170: 152, 1982 11. Leblanc JM: Patella complications in total knee arthroplasty: A literature review. Orthop Rev 18:296, 1989 12. Merkow RL, Soudry M, Insall JN: Patellar dislocation
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Daluryand Jiranek
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following total knee replacement. J Bone Joint Surg 67:1321, 1985 13. Mochizuki RM, Schurman D J: Patellar complications following total knee arthroplasty. J Bone Joint Surg 61:879, 1979 14. Ritter MA, Campbell ED: Postoperative patellar complications with or without lateral release during total knee arthroplasty. Clin Orthop 219:163, 1987
A Comparison of the Midvastus and P a r a m e d i a n A p p r o a c h e s for Total Knee Arthroplasty D a v i d F. D a l u r y , M D , * a n d W i l l i a m A. J i r a n e k , MD -[
Abstract: This prospective, double-blinded evaluation of 24 osteoarthritic patients
undergoing bilateral total knee replacement compared the midvastus and standard parapatellar approaches. The midvastus approach was found to offer an early advantage in terms of less pain and earlier return to function. There were no significant complications associated with the midvastus approach. This approach should be a part of the knee surgeon's armamentarium. Key words: total knee arthroplasty, midvastus approach, surgical approaches to the knee, total knee rehabilitation.
and involves the standard anterior midline skin incision followed by a deeper dissection that splits the vastus medialis obliquus (VMO) muscle in the direction of its fibers at its insertion into the superiormedial pole of the patella (Fig. 1 ). The distal portion of the capsular incision is identical to the routine parapatellar incision. The major advantage of this approach is the preservation of the extensor mechanism from surgical trauma. This approach has many potential benefits, including improved blood supply to the patella [5-7], fewer patellofemoral tracking problems, earlier return to function of the extensor mechanism, and less postoperative pain. This prospective, randomized, controlled study compares the standard parapatellar approach with the midvastus approach in a series of one-stage bilateral total knee replacements performed by a single surgeon.
Total knee replacement has become an accepted treatment for end-stage degenerative joint disease of the knee. The technique has become refined over the years so that now the majority of patients receive reproducible and durable relief of pain and return to function. There has been a focus on surgical technique and rehabilitation protocols as a means of improving patient outcomes. The standard midline medial parapatellar approach, initially described by Von Langenbeck in 1879 [1] provides excellent exposure to the knee and has widespread popularity and a long track record of follow-up. There have been modifications to this approach by many authors, including the straight midline approach [21, the subvastus approach [3,4], and the lateral approach. This article studies the midvastus approach and compares it with the standard parapatellar approach in a group of matched controls. The midvastus approach has been popularized by Engh (personal communication, 1994) and others
Materials and Methods Twenty-four consecutive one-stage bilateral knee replacements composed the study group. The preoperative diagnosis was osteoarthritis in all 24 patients and 48 knees. There were 16 w om en and 8 men. All procedures were performed by a single surgeon (D.ED.) via an anterior midline skin incision, and the decision as to which knee received which approach was
From *Towson Orthopaedic Associates, Johns Hopkins Hospital, Towson, MD; and ~-Tuckahoe Orthopaedics, Medical College of Virginia, VA. Submitted June 5, I997; accepted April 28, 1998. Reprint requests: David F. Dalury, MD, Towson Orthopaedic Associates, 8322 Bellona Avenue, Towson, MD 21204. Copyright © 1999 by Churchill Livingstone® 0883- 5403 / 1401-0006510.00/0
33
34
The Journal of Arthroplasty Vol. 14 No. 1 January 1999
Muscular Branch of Femoral N, henous N.
Fig. 1. Pertinent anatomy of the medial aspect of the knee.
henous Branch escending icular A. Articular Branch of Descending Genicular A.
~rior Branch escending icular A.
Lpatellar Branch aphenous N. lial Inferior icular A.
made at the time of surgery by the surgeon without regard to any preexisting criteria. All procedures were performed u n d e r regional anesthesia, and postoperative pain was managed using patientcontrolled analgesia pumps. All procedures were done u n d e r tourniquet, which was released before closure. Drains were used in all knees. All knees were posterior cruciate ligament (PCL) preserving, and all three c o m p o n e n t s were cemented. All patients received elastic stockings, intermittent compression stockings, and aspirin that was continued for 6 weeks for deep vein thrombosis prophylaxis. Preoperative alignment, range of m o t i o n (ROM), and Cybex muscle testing was done on all knees. Muscle testing on the Cybex was done at both 30 ° and 60 ° to test peak maximal torque. This testing was done preoperatively and at 6 and 12 weeks postoperatively. Physical therapists, nursing staff, and patients were blinded as to which knee had which approach. Constant passive m o t i o n (CPM) was used starting in the recovery room and continued while the patient was hospitalized, for approxi-
mately 8 hours a day, alternating each knee. Physical therapy was begun on postoperative day (POD) 1 with weight bearing as tolerated, ROM exercises, and gait training continued twice a day during the hospital stay. The tourniquet times, ROM at capsular closure, h e m o v a c drainage, visual analog pain scales, time to straight leg raising (SLR), and ROM at hospital discharge were recorded, and ROM was recorded at 6 and 12 weeks postoperatively. Radiographic analysis included anteroposterior, lateral, and sunrise views at 6 and 12 weeks.
Technique of the Midvastus Approach A standard midline skin incision was made, t h e n the fascia overlying the VMO was dissected free from the subcutaneous fat. The VMO muscle belly was t h e n split in the direction of its fibers, using a knife from a point at the superior-medial border of the patella and extended medially toward the intermuscular septum. The patella was t h e n everted, and
MidvastusApproachtoTKA t h e p r o c e d u r e w a s c a r r i e d o u t in a r o u t i n e f a s h i o n . C l o s u r e i n v o l v e d r e p a i r i n g t h e d e e p fascial l a y e r ( b e l o w t h e m u s c l e ) o n l y d o w n to t h e s u p e r i o r medial border, which was reinforced, then the r o u t i n e m e d i a l a n d i n f e r i o r c a p s u l a r repair.
Results W e s t u d i e d 24 c o n s e c u t i v e b i l a t e r a l t o t a l k n e e r e p l a c e m e n t p a t i e n t s w i t h a n a v e r a g e age of 70 y e a r s . All of t h e p a t i e n t s h a d o s t e o a r t h r i t i s . A v e r a g e w e i g h t for t h e w o m e n w a s 156 lbs a n d for t h e m e n w a s 205 lbs. A v e r a g e p r e o p e r a t i v e R O M w a s c o m p a r a b l e in t h e 2 g r o u p s of k n e e s . G r o u p 1 ( m i d v a s t u s a p p r o a c h ) R O M w a s 8 ° to 118 ° , a n d g r o u p 2 ( s t a n d a r d p a r a p a t e l l a r a p p r o a c h ) R O M w a s 7 ° to 120 ° . T o u r n i q u e t t i m e s w e r e c o m p a r a b l e for t h e 2 g r o u p s : 32 m i n u t e s for g r o u p 1 a n d 33 m i n u t e s for g r o u p 2. E s t i m a t e d b l o o d loss in t h e p o s t o p e r a t i v e d r a i n w a s 370 m L for g r o u p 1 a n d 435 m L for g r o u p 2. T h e r e w e r e n o l a t e r a l r e l e a s e s in g r o u p 1 a n d 3 l a t e r a l r e l e a s e s in g r o u p 2. R a n g e of m o t i o n at 6 w e e k s w a s 50/97 ° for g r o u p 1 a n d n o d i f f e r e n t at 601100 ° for g r o u p 2. At 3 m o n t h s , g r o u p 1 h a d a n arc of m o t i o n of 2 ° / 1 1 1 ° a n d g r o u p 2 h a d 2 ° / 1 1 3 °. T h e r e w e r e n o s i g n i f i c a n t d i f f e r e n c e s n o t i c e d b y e i t h e r g r o u p at 3 m o n t h s compared with the preoperative ROM. Preoperative standing alignment, measured on a s t a n d i n g a n t e r o p o s t e r i o r film, w a s 2 ° v a l g u s in g r o u p 1 ( r a n g e , 14 ° v a l g u s to 4 ° v a r u s ) a n d 3 ° v a l g u s in g r o u p 2 (range, 11 ° v a l g u s to 2 ° v a r u s ) . P o s t o p e r a tive a l i g n m e n t , m e a s u r e d similarly, w a s 6 ° for g r o u p 1 a n d 6.5 ° for g r o u p 2. T h e r e w e r e n o l a t e r a l releases and no patellar dislocations or subluxations in g r o u p 1. G r o u p 2 h a d 3 l a t e r a l r e l e a s e s a n d 2 p a t i e n t s w i t h m i l d p a t e l l a r tilts o n s u n r i s e v i e w at 3 months postoperatively. These conditions were not symptomatic. Quadriceps strength was tested using a Cybex m a c h i n e p r e o p e r a t i v e l y at 30 ° a n d 60 ° a n d at 6 weeks and 3-month intervals postoperatively. There w a s n o statistically significant d i f f e r e n c e in p r e o p e r a tive q u a d r i c e p s s t r e n g t h b e t w e e n t h e 2 g r o u p s , as j u d g e d b y C y b e x t e s t i n g at e i t h e r 30 ° o r 60 ° f l e x i o n (P = .5, a n a l y s i s of v a r i a n c e ) . T h e r e w a s a h i g h l y s i g n i f i c a n t d i f f e r e n c e i n q u a d r i c e p s s t r e n g t h at 6 w e e k s p o s t o p e r a t i v e l y at b o t h 30 ° a n d 60 ° , w i t h g r o u p 1 (the m i d v a s t u s a p p r o a c h ) b e i n g s t r o n g e r (P = .001). A t 3 m o n t h s p o s t o p e r a t i v e l y , t h e r e w a s n o d i f f e r e n c e in q u a d r i c e p s s t r e n g t h b e t w e e n t h e 2 g r o u p s at 30 ° f l e x i o n (P = .4), b u t t h e r e w a s a slight d i f f e r e n c e at 60 ° f l e x i o n , w i t h g r o u p 1 ( m i d v a s t u s a p p r o a c h ) b e i n g s t r o n g e r (P = .04).
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Patients overwhelmingly preferred the knees done via t h e m i d v a s t u s a p p r o a c h . Of t h e 24 p a t i e n t s , 19 e x p r e s s e d a p r e f e r e n c e a n d 5 d i d n o t . Of t h e 19 p a t i e n t s w h o h a d a p r e f e r e n c e , 17 p r e f e r r e d t h e midvastus approach, and 2 preferred the parapatellar a p p r o a c h . V i s u a l a n a l o g p a i n scales ( 0 - - n o pain and I0 = maximal pain) were recorded by the nursing staff o n POD 1, 2, a n d 3. Scores w e r e s u b s t a n t i a l l y l o w e r for g r o u p 1: 4.7, 2.9, a n d 2.1 c o m p a r e d w i t h 7.0, 5.8, a n d 4.5 for g r o u p 2. G r o u p 1 h a d a n e a r l i e r r e t u r n to SLR a n d w e r e a b l e to SLR in b e d a n a v e r a g e of 1.7 d a y s p o s t o p e r a t i v e l y v e r s u s 5.2 d a y s p o s t o p e r a t i v e l y in g r o u p 2 (Table 1). The o v e r a l l c o m p l i c a t i o n r a t e for b o t h g r o u p s w a s small. T h e r e w e r e 3 s u p e r f i c i a l h e m a t o m a s e x t e n d i n g u p i n t o t h e g r o i n in g r o u p 1 a n d n o n e in g r o u p 2. T h e s e w e r e t r a n s i e n t a n d d i d n o t i n f l u e n c e e v e n t u a l a r c of m o t i o n , r e h a b i l i t a t i o n , t r a n s f u s i o n rates, p a i n levels, o r p a t i e n t satisfaction. T h e r e w e r e n o w o u n d h e a l i n g p r o b l e m s a n d n o i n f e c t i o n s in either group. T h e r e w a s n o clinical e v i d e n c e of d e e p v e n o u s t h r o m b o s i s in e i t h e r g r o u p , a l t h o u g h n o r a d i o graphic or Doppler testing was done. There was only o n e m a n i p u l a t i o n r e q u i r e d , a p a t i e n t in g r o u p 2 who had an excellent response and eventual ROM of 4 ° / 1 2 0 ° at 3 m o n t h s p o s t o p e r a t i v e l y .
T a b l e 1. S u m m a r y of Outcomes Comparing M i d v a s t u s and Standard Approach Groups
Group 1 Midvastus
Average preop strength (foot pounds) 300/60 ° Average postop strength (foot pounds) 300/60 ° 6 weeks 12 weeks Return to straight leg raising (average) Range of motion (average) Preop Postop ( 12 weeks) Patellofemoral tracking problems Lateral releases Visual analog pain scale (0 = minimal, 10 - maximal) POD 1 POD 2 POD 3
Group 2 Standard Parapatellar
20•33
19/34
33/46 36•48
25/39 34146
1.7 days
5.2 days
8-118 ° 2-111 °
7-120 ° 2-113 °
0 0
2 patellar tilts 3
4,7 2.9 2.1
7.0 5.8 4.5
Preop, preoperative; postop, postoperative; POD, postoperative day.
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The Journal of Arthroplasty Vol. 14 No. 1 January 1999
Discussion This study was a prospective double-blinded evaluation of 2 different surgical approaches to total knee replacement. In this group of 24 osteoarthritic patients without severe deformity, the midvastus approach appeared to offer an early advantage compared with the standard parapatellar approach. The midvastus knees were less painful, had an earlier r e t u r n to function (earlier SLR, improved quadriceps strength), and were preferred by the patients compared with the standard approach. There were no significant differences in complication rates b e t w e e n the two groups. The advantages of the midvastus approach had dissipated by the 3 - m o n t h follow-up appointment. The less painful and easier rehabilitation, however, can m e a n shorter hospital stays, earlier return to function, and increased patient satisfaction. The demonstrated earlier return to function in the midvastus group most likely has to do with less trauma to the extensor mechanism. This situation allows earlier SLR and return of quadriceps strength and improves patellar tracking. There were no lateral releases in the midvastus group and no subluxations on x-ray versus 3 lateral releases and 2 mild subluxations (different patients) in the standard group. Extensor mechanism problems are the most freq u e n t complications associated with total knee replacement, including subluxation, clicking, dislocation, and avascular necrosis [8-14]. There have been other surgical approaches designed to minimize these complications, in particular, the subvastus approach [3,4]. One of the problems with the subvastus approach is difficulty visualizing the lateral tibial plateau [3]. This difficulty can lead to problems sizing, aligning, and seating the tibial component. Short, stocky, muscular, and obese legs make this problem more difficult. The midvastus approach allows better visualization of the lateral tibial plateau because only one half of the VMO needs to be mobilized as opposed to the entire VMO in the subvastus approach. Tips for minimizing visualization difficulties in challenging knees include slow, gradual knee flexion to take advantage of the viscoelastic potential of the extensor mechanism; an extension of the proximal skin incision, making certain to release Scarpa's fascia the entire length of the skin incision; extension of the medial split in the VMO all the way to the intermuscular septum; and occasionally perform a n c e of a m o r e extensive posteromedial release on the tibia, particularly in a tight varus knee. Occasion-
ally, with tight extensor mechanisms or short legs, the patella is subluxated laterally in flexion (not everted) while the distal femoral cuts are performed. Once these have b e e n done, the patella can t h e n be everted in the usual manner. Using these tips, the midvastus approach can be employed for all but the most difficult knees. There were 3 proximal and medial h e m a t o m a s in the midvastus knees. Although these did not lead to an increased need for transfusion, increased pain, or loss of motion, they certainly could have. The blood supply of the medial portion of the knee is well described. W h e n cutting across the VMO, one must be certain to visualize and electrocoagulate the n u m e r o u s perforating veins and arterial branches crossing the incision. Close attention to excellent hemostasis with inspection after letting the tourniquet d o w n is necessary. Perhaps a more tight or extensive deep fascial layer closure would have eliminated or minimized these hematomas.
Summary In this prospective, randomized, controlled study, the midvastus approach offered m a n y early advantages compared with the standard approach without any increase in the complication rate. This approach has the potential to lead to shorter hospital stays, easier rehabilitation, and increased patient satisfaction. The midvastus approach should become a part of the knee arthroplasty surgeon's a r m a m e n t a r i u m .
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MidvastusApproach toTKA 9. Cameron H, Fedorkow DM: The patella in total knee arthroplasty. Clin Orthop 165:197, 1982 10. Clayton ML, Thirupathi R: Patellar complications after total condylar arthroplasty. Clin Orthop 170: 152, 1982 11. Leblanc JM: Patella complications in total knee arthroplasty: A literature review. Orthop Rev 18:296, 1989 12. Merkow RL, Soudry M, Insall JN: Patellar dislocation
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following total knee replacement. J Bone Joint Surg 67:1321, 1985 13. Mochizuki RM, Schurman D J: Patellar complications following total knee arthroplasty. J Bone Joint Surg 61:879, 1979 14. Ritter MA, Campbell ED: Postoperative patellar complications with or without lateral release during total knee arthroplasty. Clin Orthop 219:163, 1987