Reading a Favorable Joint-Replacement Variance and Reforecasting After the Site-of-Service Shift
Valley Orthopedic Institute is the total joint replacement (TJR) service line of a 500-bed system. Q1 FY2025 was budgeted at 400 cases, $14,500 average net revenue per case, $8,200 variable cost per case, and $1,900,000 of fixed cost. Actual Q1: 340 cases, $15,900 net revenue per case, $8,050 variable cost per case, and $1,950,000 of fixed cost. Volume fell for two reasons: two surgeons left in February, and since CMS removed total knee arthroplasty from the inpatient-only list, a competing physician-owned ambulatory surgery center has been converting elective TKAs to outpatient. The board package shows one line - Q1 operating income $719,000 versus budget $620,000, favorable $99,000 - and no commentary. The CFO's three-year forecast still assumes 6% annual inpatient TJR volume growth and holds net revenue per case at the budgeted $14,500. Two further facts: 55% of TJR net revenue is Medicare, and the $15,900 average was inflated by four transfer and outlier cases that will not recur.
1. Decompose the variance into static-budget, volume, rate, variable-cost, and fixed-cost components. Show the flexible budget and explain what the $99,000 favorable line is hiding.
Read the worked answer
Static budget. Revenue 400 x $14,500 = $5,800,000; variable 400 x $8,200 = $3,280,000; contribution $2,520,000; fixed $1,900,000; operating income $620,000.
Actual. Revenue 340 x $15,900 = $5,406,000; variable 340 x $8,050 = $2,737,000; contribution $2,669,000; fixed $1,950,000; operating income $719,000.
Flexible budget at 340 cases. Revenue 340 x $14,500 = $4,930,000; variable 340 x $8,200 = $2,788,000; contribution $2,142,000; fixed $1,900,000; operating income $242,000.
Decomposition.
- Static-budget variance: $719,000 - $620,000 = $99,000 favorable
- Volume variance: $242,000 - $620,000 = $378,000 unfavorable (60 cases x $6,300 budgeted contribution per case)
- Flexible-budget variance: $719,000 - $242,000 = $477,000 favorable
- Rate variance: 340 x ($15,900 - $14,500) = $476,000 favorable
- Variable cost variance: 340 x ($8,200 - $8,050) = $51,000 favorable
- Fixed cost variance: $1,900,000 - $1,950,000 = $50,000 unfavorable
- Check: $476,000 + $51,000 - $50,000 = $477,000; $477,000 - $378,000 = $99,000.
What the single line hides. Almost all of the favorable result is price, and the price is not repeatable: four transfer and outlier cases carried most of the $1,400 per-case uplift. Strip them out and the average is closer to $14,800, cutting the rate variance to roughly $102,000. Meanwhile volume is 15% below plan on a service line with high fixed cost, which is exactly the condition that erodes margin over time. The honest headline is a $378,000 volume problem masked by a one-time price event and a favorable variable cost.
2. Rebuild the forecast for Q2 through Q4 and next year. State your assumptions explicitly and quantify the site-of-service adjustment.
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Normalize the starting point. Removing the one-off cases, use about $14,800 net revenue per case, not $15,900 and not $14,500. For variable cost, $8,050 looks sustainable; hold it flat with inflation offsetting any efficiency.
Volume. 340 cases in Q1 includes a February surgeon departure that will not annualize. A defensible run rate is 330-360 cases per quarter, call it 350, or 1,400 annualized versus the 1,600 budgeted. Do not forecast 6% growth into a base that is already 15% below budget.
Site-of-service adjustment. Assume 20% of the remaining elective TKA volume migrates to the competing ASC over the next four quarters. That is 0.20 x 1,400 = 280 cases, leaving 1,120 inpatient TJR cases. If the system captures none of that volume, the inpatient line loses 280 x $6,750 normalized contribution (about $14,800 - $8,050) = roughly $1.89 million of contribution annually. If the system opens or partners in its own outpatient site, it can recapture a share, but at a materially lower net revenue per case than the inpatient rate - model the outpatient rate separately rather than assuming the inpatient $14,800.
Rebuilt Q2-Q4. 1,050 cases at $14,800 = $15.54 million revenue; variable at $8,050 = $8.45 million; contribution $7.09 million; fixed at $1,950,000 per quarter = $5.85 million; operating income about $1.24 million for the three quarters, versus a straight-line budget of $1.86 million - a $620,000 shortfall.
Risks to state on the page. Medicare is 55% of revenue, so any rate update below the 3.1% market basket is a direct hit; the ASC migration is not reversible; two surgeons is a fragile call-coverage base; and the fixed cost base is not adjustable at this volume. Recommend a rolling forecast refreshed quarterly with a volume range of 320-370 cases per quarter.
3. The CFO also owns the reporting package. What should change in how variances reach the board?
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Report against a flexible budget, not a static one. A static-budget line tells the board that a 15% volume miss is a $99,000 win. Present three columns - actual, flexible budget at actual volume, and static budget - with the volume variance broken out separately so volume and price are never blended again.
Show price quality. Split the rate variance into rate (contractual and payer-mix) and one-time items such as transfers, outliers, and high-cost carve-outs. Boards consistently over-read a favorable price variance as sustainable improvement; a two-line split prevents that.
Add leading indicators alongside the financials. Cases scheduled 30/60/90 days out, surgeon panel by physician, share of elective TKA by site of service, payer mix, and denial rate on TJR claims. Volume problems show up in the scheduling book weeks before they show up in margin.
Attach a rolling forecast, not just a variance. A four-quarter rolling forecast with a base, upside, and downside case, re-driven from volume, rate, and cost per case. Replace the 6% growth assumption with a stated range and show the board what one standard deviation of volume is worth in dollars.
Set an accountability layer. Assign each variance to an owner - volume to the service-line medical director, rate to managed care contracting, variable cost to supply chain and OR management, fixed cost to the site administrator - and carry a named action and date for the top three unfavorable items. A variance report without an owner is a history lesson.