Intercondylar distal femoral fracture: An unreported complication of posterior stabilized total knee arthroplasty

110

The Journal

of Arthroplasty

Vol. 9 No. 1 February

1994 Significance: This study demonstrates that lncreaslng the patellar composite to two and four millimeters above the Precut thickness results in a significant increase in shearforces, potentially leading to early loosening of the component and/or increased wear. Therefore, bone conserving osteotomieswhich increase the patellar composite thickness above the precut thickness should be avoided.

patients were eqully divided. The average mediallateral dimension was 44.9mm (range 32mm 57mm). The greatest anterior-posterior thickness averaged 24mm for males and 22mm for females. The greatest anterior-posterior thickness was displaced medially and average of 4.6mm (range2.3mm-8.3mm).

Clinical

PAPER#~~ THE EFFECTS PATELLOFEMORAL ARTHROPLASTIES

OF

PATELlAR FORCES

IN

THICKNESS TOTAL

ON KNEE

Calvin S. Oishi, M.D., Honolulu, HI; Kenton R. Kaufman, Ph.D., San Diego, CA; Steven E. Irby, San Diego, CA; Clifford W. Colwell, Jr., M.D., La Jolla, CA.

Introduction: Complications related to the patellofemoral joint in total knee arthroplasty are not uncommon; and in fact represent up to 50 percent of re-operations. Bony patellar thickness has been studied because of its variability during the surgical procedure. Bone conserving osteotomizes of the patella have been recommended to maximize the strength of the resected patella. The purpose of this study is to determine the effect of a thicker patellar composite on patellofemoral compressive and shear forces. Materials and Methods: Ten unembalmed cadaver knees were studied. A posterior cruciate ligament sparing total condylar knee arthroplasty (Johnson and Johnson, PFC) was implanted. A force transducer (NK Biotechnical Engineering) which measured compression and shear was implanted into each patella. Specifications of the transducer are: maximum load = 1334.5 newtons; maximum linear deviation = 0.17 percent; maximum hysteresis = 0.25 percent; and zero shift = -0 04 percent. For each knee three thicknesses of the patellar composite (osteotomized patella, transducer, and polyethylene component) were evaluated: precut patellar thickness, precut plus two millimeters, and precut plus four millimeters. The knees were tested on the Oxford Knee Testing Rig which allowed dynamic testing with six degrees of freedom through a range of motion from 0 to 95 degrees. Statistical analysis was performed using repeated measures analysis of variance. Results:

Compressive

forces

for each

patellar

compostte

Figure

1

Figure

2

PAPER

#29

were

not significantly altered by increasing thickness (Figure 1). Total patellofemoral shear forces for the precut plus two millimeters and the precut plus four millimeters composites were significantly altered from the precut thickness (~~0.05) (Figure

2)

THREE TO EIGHT YEAR EXPERIENCE USING COUNTERSUNK METAL BACKED PATELLAS AND A DEEP TROCHLEAR GROOVED FEMORAL COMPONENT von Glinski. S., Hofmann. A.. Camargo. M.. University 111 Utah Medical Center, Salt Lake City. Utah 475 consecutive total knee arthroplasties were done using n metal hacketl. porous coated patella with smooth pegs. All components were placed with cementless technique after a hone slurry was applied to the cut surface and were countersunk at implantation. Articulation of the component is with a deep trochlear groove of the femoral component. Care was taken to not overthicken the patella with component. Optimal tracking of the patella was confirmed prior to incision closure. Patients were followed prospectively and evaluated with a modified HSS 100 point scale pre- and postoperatively. Radiographs were evaluated for patellar lucency and subluxation. Average age was 64 years (range X-82). The average total knee score was 96 at last follow-up, compared to a pre-uperative average of 5 I Pain improved from a pre-operative average of I4 out of a possible 44 to a post-operative average of 38 at the time of the last visit. Nlr complete radiolucency was seen. There were no fractures of the component nor of the remaining patellar bone. Six patients required revision of the patellar component, two for subluxation of the patellofemoral joint. and four h)r wear on young active patients or secondary to attenuation of the posterior cruciatr ligament. At reoperatinn, there was minimal hone Iwss due the The two cases of ruhluxation smooth pegs; this allowed easy revision. demonstrated mild cold tlow with wear of the edge polyethylene hutton. In the other cases that required revision, there was eccentric wear of the button and, in one case, a crack in the pulyethylene asswldted with this wear. Six post mortem specimens were donated by patients for evaluation and demonstrated excellent ingrowth (67% apposition to pious coating without fibrous interface). It is possible to ux a metal hacked patellar than d cemented all component with a complication rate no higher polyethylene patella.

INTERCONDYLAR DISTAL FEMORAL FRACTURE: AN UNREPORTED COMPLICATION OF POSTERIOR STABILIZED TOTAL KNEE ARTHROPLASTY Adolph V. Lombardi. Jr., M.D.. Robert A. Waterman, PA-C, and Robert W. Eberle: Joint Implant Surgeons, Inc., Columbus, Ohlo

Selected add,l,onal surgical ,nte,vent,o,~ Five knees I” 5 patients were noted to have d,splaced ,nte,condyla, femoral fractures detected bt the t,me of surgical ,n,erve,rt,on (rate = 1 1801 Stab,l,zat,on of these fractures required elthe, A0 Screw f,xatron arid ihe use of a stemmed femoral comwnenf (41, or A0 Screw f,xatzon only (II No changes were made ,n the standard ,+sto,xz,afwe phyzical therapy dilli ,ehab,l,tnr,on program based on the presence of displaced No sgnlf,cant differences or nond~splaced interiondylar dG,al femoral fracture were n,,ted I” the HSS SCOIES of pat,ents wth or wIthout distal femoral mtercor>dylar fractures Changmg to a system wh\ch offers a sizing block for the unercaridylnr reswt~on, we have experienced no mcldence 01 distal femoral intercondyldr fracturv /,I 532 casns

PAPER

Abstracts

From the AAHKS

Annual

Meeting

111

manipulation at 8 weeks post-op and one patient requiring a dehridement and STSG for a small marginal wound necrosis. Concluuon: Our early results are encouraging with good range of motion. improved Knee Society scores and dramatically improved ambulatory stalus and extensor mechanism function. The technique f&es upon early soft-tissue heling, and therefore late complications are not anwipated. Reconstruction of an extensor mechanism rupture following total knee arlhroplasty with a medial gastrocnemius transposition lap provides a reliable treatment option. It may be best indicated for the complicated extensor mechanism disruption m patients with poor soft tissues. connective tissue disorders and poor healing potential or in the face of exposed proythescs with lohs of Ihe extensor mechanism.

PAPER

“30

MEDIAL GASTROCNEMlUS TRANSPOSITION FLAP FOR EXTENSOR MECHANISM DISRIJPTlON AETEK TOTAL KNEE ARTHROPLASTY John W. Jaureguito, MD, Peter A. SaJob. Lawrence J. Gottlieb. MD, and Henry A. IQnn. MD: I Jniverslly of Chicago HospitaJs. Chicago. IL Purpose: WC report a new technique for salvage of a lotal knee anhroplasty followmg a disruption of the extensor mechanism by use of the medial gastfocnemius flap. Methods: Seven patients(7 knees) underwenl extensor mechanism reconstruction using a medial gastrocnemius flap. There were 6 females and one male wtth an average age of 71 years. All patients had at leas1 one comphcating factor includrng rheumatoid a&&is, infection, ankylosis, myositis ossificans. patellar mahrackmg, instability, chronic knee dislocation and scarred or contracted soft tissues around the knee secondary to multiple operative procedures. Patients were divided into 2 groups based on the type of reconstruction. Group I consisted of 5 patients (3 pate&r tendon ruptures, 2 inua-operative pate&r tendon disruptions) reconstructed with the medial gastmcnemius flap. tiroup II consisted of 2 patients(1 chronic quadriceps rupture which had failed three previous repair attempts. I infected. exposed prosthesis with necrosis of the extensor mechanism) reconstructed with the extended medial gastrocnemius-achilles tendon flap. PatienLs were evalualed by comparing preoperative and postoperative ambulatory status, range of motion, extensor lag, quadriceps suength(postoperative only), Knee Society scores and satisfaction with the surgical outcome. Group I patients preoperatively had good range of motion(zO-80”) except one patient with an ankylosed knee. ‘The average preoperative knee and functional scores were 36 and 10, respectively. 3 patients bad large extensor lags&4400) and all patients were household ambulators and walker dependent. Croup II patients preoperatively had large extensor lags and were wheelchair dependent. Knee and functional scores averaged 8 and IO. respectively. The average length of follow-up W&F one year and one patient was lost to follow-up at six months. The ueatment plan consisted of revision total knee aribroplasty when necessary(ie. septic or aseptic loosening, instability) and the soft tissue reconstruchon as described below. Postoperatively patients were immobilized in a long leg cast in extension and were started on Immediate ambulation training and isometric quadriceps exercises. At four weeks post-op. knees were placed in hinged bled% braces with progressive motion dialed into the brace and range of motion and suengthening exercises were started. Braces were worn for 8-10 weeks. Operative Technique: The midline incision is extended down the calf just medial to the tibia and a plane is developed between the medial gastrocnemius and soleus muscles. Xx medial gatrocnemius muscle is divided at its distal insertion to the achilles tendon. Proximally, the median raphe is identified and divided between the medial and laleml gasuocnemius muscle bellies. The medial gastrocnemius is diwded up to tie level of tie tibiaJ condyles W provide an adequate arc of rotation. The medral swal axtery must be preserved to provide an adequate blood supply to tie medial gastrocnemiua muscle. The muscle is transposed anteriorly at the level of the knee joint to cover the tibia1 tu&%cle and is sutured to the antenor compartment fascia. The patellar tendon and anterior joint capsule are sutured to the medial border of tic gastrwnemius flap. An optional split-thickness skin graft(STSG) may be used to cover pan of the medial gastrwnemius flap. The technique can be altered to reconstruct the entire extensor mechanism. The inciston IS extended as described above. The medial one dCrd to one half of Ihe achilles tendon is taken in its continuity with the medial gasuocrtemius muscle and the entire flap is transposed anreriorly as described above. The deep gastmcnemius fascia IS approximated to the tibraJ tubercle with suture or wires through drill holes The achilles tendon portion of the flap is then brought proximally and sutured to the quadriceps tendon under maximum tenston wtth the knee in full extension. Once again, a STSG can be used if needed. Results: Pa&n& in Group I postoperatively had an average range of motion of O90”. an average extensor lag of 11”. and average knee and functional scores of 89 and 76, respectively. Preoperative knee and functional scores increased an average of 53 and 66 points, respectively. All patients had S/5 quadriceps strength. Patients ambulatory sratm improved from household ambulator walker dependent preoperatively to commumty ambulation unassisted postoperatively. Patellar height remained stable on postoperative radiographs in all patients. All patlen& were satisfied with their surgical outcome. Patients in Group II postoperatively had a range of motion >O-loo”. extensor lags of 40” and 45”. and 315 quadriceps suenglh. Knee and functional scores averaged 80 and 53 points: an average mcrcase of 72 and 43 points. respectively. Their ambulatory states improved from wheelchair dependenr 10 communiry ambulation with assistive devxes. PatelIar height remained stable on postoperative radiographs. Both patients were satrsfied with therr result Complications mcluded one pattent requiring a

Third

MANAGING TOTAL KNEE

ACUTE AND ARTHROPIASTY

“31 CHRONIC

INFECTED

Kirby D. Hitt. M.D., Temple, TX; Lester S. Harden. M.D., Cleveland. OH Deep infection following total knee arrhroplasty is not always amenable to antibioric therapy. In an cfforr to reduce the incidence of potentially disabling complications from acute or chronic infection, we comlxwed the effectiveness of the surgical debridement, prosthetic retention procedure with other therapeutic options. We followed 48 patients who bad 50 total knee arthroplasties complicated primarily by .Srup~~lococcrts c~~~T-c~‘s or Stup~ylococcu~ epidermidis infections for an average of 7.6 years. Among these patients, seven knees became acutely infected within two weeks after surgery: surgical debridement and prosthetic retention prevented recurrent The remaining 43 infections in 86% of these patients. knees experienced a chronic postoperative infection; delayed reimplantations prevented infection in 96% of these patients. Following reimplantation. however, seven patients subsequently suffered knee joint sepsis with an organism differing from the initial infective agent. and two patients demonstrated progressive radiolucency. Moreover. a higher incidence of recurrent infections was associated with intramedullary stems. Our long-term study of patients who develop infections after total knee arthroplasty indicates that surgical debridement and prosthetic retention is an effective treatment for acute infection, while the delayed reimplantation procedure is effectfive against chronic infection.

PAPER

#32

-

Da\,e Wallace. Tucson. AZ The UHMWPE content of synov~al fluid lrom 13 parrents undergoing revlslon total knee arthroplastv was subjected to chemical digestIon, to remove the organic components, and ultrafiltered. Scanntng electron microscopy (SEM) was used to visualize UHMWPE parhcles and the Images were analyz.ed usmg dIgital Imaging software. Parameters evaluated Included particle size, shape and number, as well as particles per volume of synovial fluld. This data was correlated with polyethylene wear patterns seen at the time of revision surgery. The knees had been In situ for periods ranging from 3-l 13 months, and included SIX different prosthettc designs. The mean area of individual polyethylene parricles measured for each patient ranged from 41 to 701 p2, and the total number of parhcles tdentlrled for each sample ranged from 38 to 279. The largest particle identified had a surface area of 17,500 ~2. The particle area per ml of synovlal flurd examined w’as calculated, and values ranged from 6.22~10~ to 2.06x 106 $/ml. The mean concent&ton of UHMWPE In those knees with gross wear was 9.9x 16 p versus 1.3 s IO5 p In knees without gross wear (p= 0.047). There was also a trend towards lncreaslng particle area m knees with gross