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Percutaneous intramedullary fixation of metacarpal shaft fractures
P E R C U T A N E O U S I N T R A M E D U L L A R Y F I X A T I O N OF METACARPAL SHAFT FRACTURES A. A. FARAJ and T. R. C. DAVIS
From the Department oJ Trauma and Orthopaedic' Surgery, Queen's'Medical Centre, University Hospital, Nottingham, UK Twenty-two displaced metacarpal shaft fractures in 19 patients were stabilized with multiple intramedullary K-wires. These were inserted percutaneously through a small window in the base of the metacarpal and were buried in the bone. No external splintage was routinely used postoperatively and all patients were encouraged to mobilize their fingers immediately: formal physiotherapy was not usually required. All the fractures that we were able to follow-up united, but the K-wires bent at the fracture site in two instances, producing 20 ° angular deformities. The buried K-wires had to be removed in one instance as a result of protrusion into the carpometacarpal joint.
Journal of Hand Surgery (British and European Volume, 1999) 24B." 1:76-79 Technique
The functional outcome of fractures of the little and ring metacarpal shafts is usually very good, even if the fracture unites with significant angular malunion. However, angular malunion of more than 30 ° can cause significant cosmetic deformity and dorsal translation of the fracture, which allows complete fracture step-off, may cause unacceptable shortening. If the position of a fresh transverse or oblique fracture is deemed unacceptable, it can be treated with a variety of techniques, including intramedullary K-wire fixation. This technique can usually be performed percutaneously, with minimal soft-tissue dissection and without exposure of the fracture or periosteal elevation. It thus should not cause extensor tendon adhesions. The use of specially manufactured intramedullary wires for metacarpal shaft fractures has been reported (Gonzalez et al., 1995) and others have stabilized metacarpal neck fractures with intramedullary K-wires that are inserted through a cortical window at the base of the metacarpal (Foucher, 1995; Manueddu and Della Santa, 1996). The ends of the K-wires were not buried in the metacarpal in any of these series and in one they were routinely removed after fracture union (Foucher, 1995). All three studies reported good results with few complications. This study reports our experience with intramedullary wiring of metacarpal shaft fractures.
Our technique for intramedullary wiring evolved with experience and is similar to that described by Manueddu and Della Santa (1996). K-wires (0.9 mm) are bent to form a gentle curve and their tips are cut off. One end of each wire is then fashioned into a handle to allow rotation of the wire during insertion and the other end is bent so as to produce a 30 ° angulation 5 mm proximal to the blunt tip: this facilitates the passage of the wire across the fracture. Under general anaesthesia and with a tourniquet around the upper arm, a small incision is made on the ulnar border of the base of the little finger metacarpal or on the dorsal aspect of the base of the ring or the middle metacarpal. Using image intensification, a small cortical window is then created in the metacarpal base, approximately 1 cm distal to the carpometacarpal joint. A handheld awl is used to start the cortical window that is then enlarged with hand-held burrs that are introduced obliquely in both proximal and distal directions so as to faciliate subsequent intramedullary wire insertion and create a hollow in the metacarpal base. The fracture is reduced closed and a prebent K-wire is inserted through the cortical window into the intramedullary canal. Using image intensification it is then passed distally across the fracture so that its tip lies within the metacarpal head. This procedure is relatively simple when the intramedullary canal is wide, but can be difficult if it is narrow. After insertion of the first K-wire, a further one, two or three K-wires are passed across the fracture in the same manner. Initially we used one or two stouter wires, but we later used three or four intramedullary 0.9 mm Kwires whenever possible. The protruding ends of the Kwires are then cut flush with the cortical window, grasped with an artery clip and pushed into the medullary canal and down into the base of the metacarpal so that they cannot retract out of the cortical window (Fig 1). Finally, the metacarpal shaft fracture is compressed to ensure bony apposition, the skin wound is closed with subcuticular vicryl and a crepe bandage is
PATIENTS AND M E T H O D S Twenty-two acute metacarpal shaft fractures in 19 patients (16 male, 3 female) with a mean age of 28 years (range, 18-46 years) were treated with intramedullary Kwires between 1991 and 1996. The fracture pattern was oblique in 13 and transverse in nine. The vast majority of injuries occurred in the dominant hand, usually as a result of fighting. Only fractures with more significant angulation or displacement were offered operative treatment and all patients were offered the option of conservative management.
76
INTRAMEDULLARY FIXATION
77
Table 1--The number of intramedullary K-wires used to stabilize the metacarpal shaft fractures
Metacarpal
Fig 1
PA radiograph of oblique fracture of distal shaft of little finger metacarpal that has been stabilized with three intermedullary K-wires. The callus formation and cortical lucency on the ulnar aspect of the base of the metacarpal indicate the location of the cortical window for insertion of the K-wires. This window is 1 cm distal to the carpometacarpal joint and distal to the proximal ends of the intramedullary K-wires that have been pushed down into the base of the metacarpal.
applied. Patients are encouraged to move the fingers and are discharged home on the same day without formal physiotherapy. RESULTS We were unable to insert the K-wires percutaneously into one metacarpal with a narrow medullary canal and had to expose the fracture. Early in the series, when we only
Middle
Ring
Little
One K-wire Two K-wires Three K-wires
1 2 0
1 1 2
4 5 6
Total
3
4
15
used one K-wire for each fracture, two patient's hands were immobilized in plaster for 3 weeks. Two cases were referred for physiotherapy. The fractures treated in this series and number of K-wires used are shown in Table 1. Most patients needed little postoperative treatment and several patients were never seen again following discharge from hospital. However, all who attended their 2week postoperative appointment had regained virtual pain-free, full hand movements. Ten of our 19 patients were lost to follow-up within 6 weeks of surgery, but we were able to speak to three of these on the telephone 9 months after injury and a further two represented to the fracture clinic with other hand fractures, thus allowing both clinical and radiological follow-up. Eleven of these 14 patients with follow-up quickly regained full painless hand function but two still complained of aching discomfort at the fracture site 3 months following surgery. X-rays showed that their intramedullary wires had bent at the fracture site, allowing recurrent fracture angulation (Fig 2), but hand function was satisfactory and both fractures had united. The K-wires had to be removed in two cases at the beginning of the study when we did not bury them in the metacarpal base. They also had to be removed in a third case in which the cortical window was right at the base of the metacarpal and had broached the carpometacarpal joint. This allowed the buried K-wires to migrate proximally into the carpometacarpal joint causing pain and restricting hand function. A further complication occurred in a little finger metacarpal shaft fracture that was treated satisfactorily with three intramedullary K-wires. One year later this man punched a wall and sustained a fracture of the same metacarpal neck, through which the K-wires protruded into the soft-tissues on the extensor surface of the hand. After the wires had been removed the fracture healed uneventfully with restoration of full function. DISCUSSION Most fractures of the shafts of the ring and little finger metacarpals can be managed conservatively as the functional outcome is usually good, even if the fracture unites with significant angular (flexion) deformity. Operative fixation is only required when there is rotational deformity or marked shortening and when the surgeon considers that the angular deformity will cause an
78
Fig2
THE JOURNAL OF HAND SURGERY VOL. 24B No. 1 FEBRUARY 1999
(a, b) Preoperative PA and lateral radiographs of fractures of the shafts of the little and ring finger metacarpals. The lateral view shows dosral translation and step-off of the distal fragments. (c, d) Radiographs of the same hand taken 4 weeks after intramedullary fixation. The fracture step-off has been corrected but the wires in the little finger metacarpal have bent slightly at the fracture site, allowing slight flexion of the fracture.
I N T R A M E D U L L A R Y FIXATION
unacceptable cosmetic deformity. Although it has been suggested that angular malunion and shortening can cause hand weakness, this has never been demonstrated clinically. Our experience with intramedullary K-wiring of metacarpal shaft fractures is that, if performed carefully, it provides a relatively safe form of fracture stabilization and allows early mobilization of the hand. Although others have routinely cut the K-wires flush with the bone (Gonzalez et al., 1995; Manueddu and Della Santa, 1996), or left them protruding from the metacarpal base and removed them after fracture union (Foucher, 1995), our practice is to bury the K-wires in the base of the metacarpal. This prevents them from retracting into, or impinging on, the overlying soft-tissues which might interfere with rehabilitation and necessitate their removal after fracture union. This practice appears satisfactory, provided care is taken to ensure that the cortical window in the metacarpal base is 1 cm distal to the carpometacarpal joint and the patient does not sustain a further fracture of the same metacarpal. Intramedullary K-wire fixation is probably unsuitable for spiral and severely comminuted shaft fractures. As none of our fractures presented with rotational deformity, we cannot recommend their use in this instance even though others consider that splaying of the ends of the wires in the head of the metacarpal will control rotation (Gonzalez et al., 1995). Alternatively, rotational deformity could be prevented with an additional transverse K-wire that transfixes the heads of the fractured and the adjacent metacarpals. Intramedullary K-wire fixation does not produce rigid internal fixation and the wires will sometimes bend at the fracture site, allowing recurrent angular deformity (Fig 2). However, we did not observe any severe cases of recurrent angular deformity and the wires will prevent recurrent dorsal fracture translation and step-off and thus should prevent the development of a significant cosmetic deformity. Although there is undoubtedly a learning curve for this procedure, with experience the tourniquet time can be reduced to 20 to 30 minutes. The
79
technique is simplest for the little finger metacarpal and, if the cortical window is properly placed, the K-wires can be safely buried and should not require subsequent removal. We feel that, as for the femur and tibia, intramedullary fixation is most suitable for midshaft fractures occurring near the narrowest part of the medullary canal. Our technique is unsuitable for proximal metaphyseal fractures and, though intramedullary wire fixation has been recommended for neck fractures (Foucher, 1995; Manueddu and Della Santa, 1996), the medullary canal is wide in this region and we are concerned that the fixation might not prevent fracture redisplacement. Furthermore fractures of the necks of the little and ring finger metacapals, even if markedly displaced, cause little if any functional disability (Hunter and Cowen, 1970) and produce less cosmetic deformity than shaft fractures. Although plate fixation can provide rigid fixation in anatomical alignment, it can cause extensor tendon adhesions and the plate and surrounding new bone formation on the back of the metacarpal can cause an appreciable cosmetic deformity. We consider that intramedullary K-wire fixation is cost-effective and appropriate for transverse and oblique fractures of the shafts of the little and ring finger metacarpals: formal physiotherapy is not required and outpatient follow-up is not critical. REFERENCES Foucher G (1995). "Bouquet" osteosynthesis in metacarpal neck fractures: a series of 66 patients. Journal of Hand Surgery, 20A: $86-$89. Gonzalez MH, lgram CM, Hall R F (1995). Flexible intramedullary nailing for metacarpal fractures. Journal of Hand Surgery, 20A: 382-387. Hunter JM, Cowen NJ (1970). Fifth metacarpal fractures in a compensation clinic population. Journal of Bone and Joint Surgery, 52A: 1159 1165. Manueddu CA, Della Santa D (1996). Fasciculated intramedullary pinning of metacarpal fractures. Journal of Hand Surgery, 21 B: 23(~236. Received: 3 July 1998 Accepted after revision: 29 September 1998 T. R. C. Davis FRCS, Department of Trauma and Orthopaedic Surgery, Queen's Medical Centre, University Hospital, Nottingham NG7 2UH, U K. © 1999The British Society for Surgery of the Hand Article no. jhsb. 1998.0031
From the Department oJ Trauma and Orthopaedic' Surgery, Queen's'Medical Centre, University Hospital, Nottingham, UK Twenty-two displaced metacarpal shaft fractures in 19 patients were stabilized with multiple intramedullary K-wires. These were inserted percutaneously through a small window in the base of the metacarpal and were buried in the bone. No external splintage was routinely used postoperatively and all patients were encouraged to mobilize their fingers immediately: formal physiotherapy was not usually required. All the fractures that we were able to follow-up united, but the K-wires bent at the fracture site in two instances, producing 20 ° angular deformities. The buried K-wires had to be removed in one instance as a result of protrusion into the carpometacarpal joint.
Journal of Hand Surgery (British and European Volume, 1999) 24B." 1:76-79 Technique
The functional outcome of fractures of the little and ring metacarpal shafts is usually very good, even if the fracture unites with significant angular malunion. However, angular malunion of more than 30 ° can cause significant cosmetic deformity and dorsal translation of the fracture, which allows complete fracture step-off, may cause unacceptable shortening. If the position of a fresh transverse or oblique fracture is deemed unacceptable, it can be treated with a variety of techniques, including intramedullary K-wire fixation. This technique can usually be performed percutaneously, with minimal soft-tissue dissection and without exposure of the fracture or periosteal elevation. It thus should not cause extensor tendon adhesions. The use of specially manufactured intramedullary wires for metacarpal shaft fractures has been reported (Gonzalez et al., 1995) and others have stabilized metacarpal neck fractures with intramedullary K-wires that are inserted through a cortical window at the base of the metacarpal (Foucher, 1995; Manueddu and Della Santa, 1996). The ends of the K-wires were not buried in the metacarpal in any of these series and in one they were routinely removed after fracture union (Foucher, 1995). All three studies reported good results with few complications. This study reports our experience with intramedullary wiring of metacarpal shaft fractures.
Our technique for intramedullary wiring evolved with experience and is similar to that described by Manueddu and Della Santa (1996). K-wires (0.9 mm) are bent to form a gentle curve and their tips are cut off. One end of each wire is then fashioned into a handle to allow rotation of the wire during insertion and the other end is bent so as to produce a 30 ° angulation 5 mm proximal to the blunt tip: this facilitates the passage of the wire across the fracture. Under general anaesthesia and with a tourniquet around the upper arm, a small incision is made on the ulnar border of the base of the little finger metacarpal or on the dorsal aspect of the base of the ring or the middle metacarpal. Using image intensification, a small cortical window is then created in the metacarpal base, approximately 1 cm distal to the carpometacarpal joint. A handheld awl is used to start the cortical window that is then enlarged with hand-held burrs that are introduced obliquely in both proximal and distal directions so as to faciliate subsequent intramedullary wire insertion and create a hollow in the metacarpal base. The fracture is reduced closed and a prebent K-wire is inserted through the cortical window into the intramedullary canal. Using image intensification it is then passed distally across the fracture so that its tip lies within the metacarpal head. This procedure is relatively simple when the intramedullary canal is wide, but can be difficult if it is narrow. After insertion of the first K-wire, a further one, two or three K-wires are passed across the fracture in the same manner. Initially we used one or two stouter wires, but we later used three or four intramedullary 0.9 mm Kwires whenever possible. The protruding ends of the Kwires are then cut flush with the cortical window, grasped with an artery clip and pushed into the medullary canal and down into the base of the metacarpal so that they cannot retract out of the cortical window (Fig 1). Finally, the metacarpal shaft fracture is compressed to ensure bony apposition, the skin wound is closed with subcuticular vicryl and a crepe bandage is
PATIENTS AND M E T H O D S Twenty-two acute metacarpal shaft fractures in 19 patients (16 male, 3 female) with a mean age of 28 years (range, 18-46 years) were treated with intramedullary Kwires between 1991 and 1996. The fracture pattern was oblique in 13 and transverse in nine. The vast majority of injuries occurred in the dominant hand, usually as a result of fighting. Only fractures with more significant angulation or displacement were offered operative treatment and all patients were offered the option of conservative management.
76
INTRAMEDULLARY FIXATION
77
Table 1--The number of intramedullary K-wires used to stabilize the metacarpal shaft fractures
Metacarpal
Fig 1
PA radiograph of oblique fracture of distal shaft of little finger metacarpal that has been stabilized with three intermedullary K-wires. The callus formation and cortical lucency on the ulnar aspect of the base of the metacarpal indicate the location of the cortical window for insertion of the K-wires. This window is 1 cm distal to the carpometacarpal joint and distal to the proximal ends of the intramedullary K-wires that have been pushed down into the base of the metacarpal.
applied. Patients are encouraged to move the fingers and are discharged home on the same day without formal physiotherapy. RESULTS We were unable to insert the K-wires percutaneously into one metacarpal with a narrow medullary canal and had to expose the fracture. Early in the series, when we only
Middle
Ring
Little
One K-wire Two K-wires Three K-wires
1 2 0
1 1 2
4 5 6
Total
3
4
15
used one K-wire for each fracture, two patient's hands were immobilized in plaster for 3 weeks. Two cases were referred for physiotherapy. The fractures treated in this series and number of K-wires used are shown in Table 1. Most patients needed little postoperative treatment and several patients were never seen again following discharge from hospital. However, all who attended their 2week postoperative appointment had regained virtual pain-free, full hand movements. Ten of our 19 patients were lost to follow-up within 6 weeks of surgery, but we were able to speak to three of these on the telephone 9 months after injury and a further two represented to the fracture clinic with other hand fractures, thus allowing both clinical and radiological follow-up. Eleven of these 14 patients with follow-up quickly regained full painless hand function but two still complained of aching discomfort at the fracture site 3 months following surgery. X-rays showed that their intramedullary wires had bent at the fracture site, allowing recurrent fracture angulation (Fig 2), but hand function was satisfactory and both fractures had united. The K-wires had to be removed in two cases at the beginning of the study when we did not bury them in the metacarpal base. They also had to be removed in a third case in which the cortical window was right at the base of the metacarpal and had broached the carpometacarpal joint. This allowed the buried K-wires to migrate proximally into the carpometacarpal joint causing pain and restricting hand function. A further complication occurred in a little finger metacarpal shaft fracture that was treated satisfactorily with three intramedullary K-wires. One year later this man punched a wall and sustained a fracture of the same metacarpal neck, through which the K-wires protruded into the soft-tissues on the extensor surface of the hand. After the wires had been removed the fracture healed uneventfully with restoration of full function. DISCUSSION Most fractures of the shafts of the ring and little finger metacarpals can be managed conservatively as the functional outcome is usually good, even if the fracture unites with significant angular (flexion) deformity. Operative fixation is only required when there is rotational deformity or marked shortening and when the surgeon considers that the angular deformity will cause an
78
Fig2
THE JOURNAL OF HAND SURGERY VOL. 24B No. 1 FEBRUARY 1999
(a, b) Preoperative PA and lateral radiographs of fractures of the shafts of the little and ring finger metacarpals. The lateral view shows dosral translation and step-off of the distal fragments. (c, d) Radiographs of the same hand taken 4 weeks after intramedullary fixation. The fracture step-off has been corrected but the wires in the little finger metacarpal have bent slightly at the fracture site, allowing slight flexion of the fracture.
I N T R A M E D U L L A R Y FIXATION
unacceptable cosmetic deformity. Although it has been suggested that angular malunion and shortening can cause hand weakness, this has never been demonstrated clinically. Our experience with intramedullary K-wiring of metacarpal shaft fractures is that, if performed carefully, it provides a relatively safe form of fracture stabilization and allows early mobilization of the hand. Although others have routinely cut the K-wires flush with the bone (Gonzalez et al., 1995; Manueddu and Della Santa, 1996), or left them protruding from the metacarpal base and removed them after fracture union (Foucher, 1995), our practice is to bury the K-wires in the base of the metacarpal. This prevents them from retracting into, or impinging on, the overlying soft-tissues which might interfere with rehabilitation and necessitate their removal after fracture union. This practice appears satisfactory, provided care is taken to ensure that the cortical window in the metacarpal base is 1 cm distal to the carpometacarpal joint and the patient does not sustain a further fracture of the same metacarpal. Intramedullary K-wire fixation is probably unsuitable for spiral and severely comminuted shaft fractures. As none of our fractures presented with rotational deformity, we cannot recommend their use in this instance even though others consider that splaying of the ends of the wires in the head of the metacarpal will control rotation (Gonzalez et al., 1995). Alternatively, rotational deformity could be prevented with an additional transverse K-wire that transfixes the heads of the fractured and the adjacent metacarpals. Intramedullary K-wire fixation does not produce rigid internal fixation and the wires will sometimes bend at the fracture site, allowing recurrent angular deformity (Fig 2). However, we did not observe any severe cases of recurrent angular deformity and the wires will prevent recurrent dorsal fracture translation and step-off and thus should prevent the development of a significant cosmetic deformity. Although there is undoubtedly a learning curve for this procedure, with experience the tourniquet time can be reduced to 20 to 30 minutes. The
79
technique is simplest for the little finger metacarpal and, if the cortical window is properly placed, the K-wires can be safely buried and should not require subsequent removal. We feel that, as for the femur and tibia, intramedullary fixation is most suitable for midshaft fractures occurring near the narrowest part of the medullary canal. Our technique is unsuitable for proximal metaphyseal fractures and, though intramedullary wire fixation has been recommended for neck fractures (Foucher, 1995; Manueddu and Della Santa, 1996), the medullary canal is wide in this region and we are concerned that the fixation might not prevent fracture redisplacement. Furthermore fractures of the necks of the little and ring finger metacapals, even if markedly displaced, cause little if any functional disability (Hunter and Cowen, 1970) and produce less cosmetic deformity than shaft fractures. Although plate fixation can provide rigid fixation in anatomical alignment, it can cause extensor tendon adhesions and the plate and surrounding new bone formation on the back of the metacarpal can cause an appreciable cosmetic deformity. We consider that intramedullary K-wire fixation is cost-effective and appropriate for transverse and oblique fractures of the shafts of the little and ring finger metacarpals: formal physiotherapy is not required and outpatient follow-up is not critical. REFERENCES Foucher G (1995). "Bouquet" osteosynthesis in metacarpal neck fractures: a series of 66 patients. Journal of Hand Surgery, 20A: $86-$89. Gonzalez MH, lgram CM, Hall R F (1995). Flexible intramedullary nailing for metacarpal fractures. Journal of Hand Surgery, 20A: 382-387. Hunter JM, Cowen NJ (1970). Fifth metacarpal fractures in a compensation clinic population. Journal of Bone and Joint Surgery, 52A: 1159 1165. Manueddu CA, Della Santa D (1996). Fasciculated intramedullary pinning of metacarpal fractures. Journal of Hand Surgery, 21 B: 23(~236. Received: 3 July 1998 Accepted after revision: 29 September 1998 T. R. C. Davis FRCS, Department of Trauma and Orthopaedic Surgery, Queen's Medical Centre, University Hospital, Nottingham NG7 2UH, U K. © 1999The British Society for Surgery of the Hand Article no. jhsb. 1998.0031